Primate Behavioural Ecology Flashcards

Question

What adaptation does the presence of mammary glands in mammals relate to?

Answer 1

related to long gestation periods and long life expectancy. Milk production is an adaptation enabling intense maternal or parental care of the offspring, needed due to this long maturation period

Answer 2

adaptation to their diverse diets Increased learning and behavioural flexibility

Answer 3

non-linear relationship between two factors

Answer 4

General biological law: brain size increases with body size Adaptation: below or above the allometric line (smaller or larger than expected, relative to body size)

Answer 5

The Jarman-Bell principle states that the food quality of a herbivore's intake decreases as the size of the herbivore increases, but the amount of such food increases to counteract the low quality foods. So large animals need a lot of food, and to fulfil their high energetic requirements, they will rely on abundant but poor-quality food. Large herbivores, like gorillas, need to eat a lot of poor-quality food such as grass and leaves. On the contrary, smaller apes like chimpanzees, who eat mostly ripe fruits need less quantity of these food since they are of better quality, even if they are rare These requirements thus constrain the habitats occupied by animals

Answer 6

No even if this rule is true for most herbivores and frugivores, it doesn’t exactly apply to omnivores, probably due to the diverse quality of their diet. This also explains, to some extent (as it is not the only explanation) why omnivores, like humans or rats, can occupy diverse ecological niche

Answer 7

high degree of prehensility Five digits Opposable thumb Divergent and partially opposable big toe clavicle

Answer 8

Ateles (spider monkeys) don’t have a thumb. They still have the bones of the thumb, even if very small, but they don’t possess anymore a separated thumb. This corresponds to a secondary loss (their ancestors had a thumb, but they lost the usage of it). Their hands form a perfect hook that allows them to swing from branch to branch

Answer 9

have a prehensile tail, which may be related to lacking the use of a thumb.

Answer 10

None Since primate’s opposable thumb allows them to grasp and grip on substrates, on the contrary to many mammals, primates have nails instead of claws. Primates also have tactile pads with enriched sensory nerves terminations at the tip of the digits

Answer 11

e due to their ability to sit on their butt, due to their ability to jump and leap, and due to their standing habits for some of them (e.g. gibbons, chimpanzees and bonobos). most primates already show some forms of pre-adaptation for bipedalism.

Answer 12

It allows them to move their arms and shoulders away from the body. Clavicle constitutes a pre-adaptation for intense tool use, such as nut cracking, a behaviour observed in chimpanzees, capuchins and macaques

Answer 13

clinging on tree trunks and leaping from branch to branch. | Galagos

Answer 14

eg gibbons and spider monkeys eg orang-utans and some lemur species

Answer 15

the body sizes of primates determine which kind of substrates they can use. Small primates can then be arboreal, either walking on four limbs or jumping and clinging, while larger arboreal primates like orang-utans tend to hang on large substrates like large branches. Orang-utans also use the flexibility of tree trunks to save energy when moving in the canopy. Some primate species spend most of their time on the ground, being terrestrial, where they most of the time walk as quadrupeds. Others live in trees but prefer a suspensory mode of locomotion (e.g. spider monkeys)

Answer 16

baboons, patas monkeys and chimpanzees. They eat mostly fruits, but also leaves, seeds, nuts, insects and sometimes meat.

Answer 17

Yes reflected in the shape of their teeth

Answer 18

Frugivore primates eat mostly fruits (e.g. most of cercopithecines as macaques and arboreal forest guenons). Folivores, eat mostly leaves and grass, like all colobines but also gorillas. Folivore dietary specialisations are not only reflected in the teeth, but also in the structure of the gut In particular, colobines, who eat lots of leaves, have a stomach with several chambers, just like ruminants. Many prosimians are insectivore.

Answer 19

Primates rely much more on vision than olfaction; they display morphological adaptations on their skull, eyes and brain related to this reliance on vision.

Answer 20

A particular adaptation is that primates see the world in colour (trichromatic or dichromatic ). Primate vision is also different from other mammals as they can see in three dimensions, due to their stereotypic vision, which is enabled by forward facing eyes. This stereotypic vision allows the right and left visual field to cross, enabling a vision in three dimensions

Answer 21

allows them to thrive in trees and to adopt an arboreal | life; it also allows them to catch mobile insects and preys by sight

Answer 22

reflected in their morphological facial features, with a reduced snout. Most primates have a relatively flat nose

Answer 23

Prosimians still rely a lot more on smell and they have a prolonged muzzle and less forward facing eyes. anthropoids have a shorter snout and much more forward-facing eyes.

Answer 24

eduction of the olfactive lobe in monkeys as compared to prosimians, and even more reduced in chimpanzees compared to monkeys.

Answer 25

: a long period of growth and maturation requires intense maternal and parental care, as well as a great dependence on flexible learned behaviour (e.g. peering behaviour of young orangutans who take years to learn everything by observing their mother and older siblings). A consequence of the dependence on flexible learned behaviour is that most primates live in groups, with other group members from who they can learn, and most primates are diurnal.

Answer 26

primates live in stable groups; they form long-term relationships similar to friendships, allowing them to reciprocate and cooperate (e.g. sharing food); overlapping generations live together, opening opportunities to learn socially from older individuals, leading to the emergence of animal cultures.

Answer 27

all primate species are located in tropical and subtropical areas, in Africa, in Asia and in South-America all the way North to Mexico in general primates (including humans) are tropical species.

Answer 28

``` e Japanese macaques, who can survive to hard winters due to their specific thermoregulatory behaviour (hot springs bathing and huddling behaviour). ```

Answer 29

75% of living primate species are located in only 4 megadiverse countries: Republic Democratic of Congo, Madagascar, Brazil and Indonesia.

Answer 30

Lemurs, loris and galagos are the most primitive primates, of which the last common ancestor with humans goes back to more than 60 million years Strepsirrhinii

Answer 31

``` Strepsirrhinii Tarsiers (forming part of the prosimians) Platyrrhines Old World monkeys Lesser apes apes (these 3 are the Catyrrhines) ```

Answer 32

Catyrrhines and Platyrrhines together

Answer 33

, the group where Anthropoids and tarsiers are together

Answer 34

include the lemurs (e.g. arboreal ruffed lemur and terrestrial ring-tailed lemur). Prosimians also include the aye-aye, with their specialised finger to fish on insects and gum in tree holes, and the smallest living primate on earth, the mouse lemur.

Answer 35

Yes in Africa and Asia, but not in the Americas. They include the antwantibos, pottos, bushbabies (galagos) found in Africa the lorises found in Asia. All of these prosimians living outside of Madagascar are nocturnal

Answer 36

only in South-East Asia. They are tiny nocturnal creatures, and are extremely vulnerable to the pet trade in these regions

Answer 37

Small body size Mostly solitary Males home-ranges larger than and encompass female‘s Still rely a lot on smell Mostly nocturnal Eat insects and fruits some species of lemurs live in groups, during the day, and display a female dominance over the males

Answer 38

giant lemurs

Answer 39

South America and South of Mexico

Answer 40

the marmosets and the tamarins they are cooperative breeders, where members of the group help raising the offspring of a dominant couple or of a dominant female

Answer 41

Capuchins: „chimpanzees of America“

Answer 42

Variable body size Group-living Often cooperative breeders Mostly diurnal (a h few species living at night (owl monkeys)) Dichromatic vision Variable social systems (polyandry, harems, multi-male multi-female)

Answer 43

marmosets and tamarins being quite small but spider monkeys can be up to 15kg.

Answer 44

(old world monkeys) include Ceropithecines and Colobines

Answer 45

baboons and assimilated species like the mandrills, but also the macaques and the langurs.

Answer 46

no also include eg langurs and colobus

Answer 47

variable sizes and live in groups of variable sizes strict hierarchical dominance system (often female philopatry) variable social systems, from harem systems to multi-male multi-female systems. They are strictly diurnal

Answer 48

females born in a group stay in that group while males emigrate when they are sexually mature

Answer 49

folivores - have a stomach with several chambers like cows live in harem systems and infanticide is common and a high risk for females

Answer 50

multi-male multi-female societies mostly frugivores and omnivores, females present exaggerated sexual swellings when they are receptive

Answer 51

Gibbons and siamangs are the lesser apes.

Answer 52

only in Asia

Answer 53

no tail, monogamous, both male and female disperse at sexual maturity, strictly diurnal their locomotor mode is brachiation. They are famous for the duet singing

Answer 54

Africa and South-East Asia

Answer 55

no tail, strictly diurnal (even if some populations may be quite active at night like some Ugandan chimpanzees doing crop raiding during nights of full moon).

Answer 56

social systems go from semi-solitary for orang-utans to multi-male multifemale societies for bonobos and chimpanzees, while most gorilla populations are living in one-male units (harems). Bonobos and chimpanzees have a female dispersal system. Female bonobos are codominant with males, while chimpanzee males are dominant over the females

Answer 57

Semi-solitary Long dependency period Borneo + Sumatra

Answer 58

Harems Multi-male multi-female Male and female dispersal Strong sexual dimorphism

Answer 59

multi-male multi-female co-dominant female dispersal

Answer 60

multi-male multi-female male dominance female dispersal

Answer 61

Adaptations: characteristics that improve an organism‘s chances for survival and/or reproduction Adaptations: functional traits passed down through the next generations Adaptations: maintained through evolution and selection

Answer 62

2 phenotypes: black or white like to hang out on the bark of white birch trees. Before the industrial revolution of the 19th century, most of birch trees had a white bark, and the two types of moths had a distinctive advantage toward predators: the black ones were very visible, while the white one could hide on the bark. Then came the industrial revolution which emitted a lot of black smoke in the atmosphere. These particles accumulated on the bark of the surrounding trees, so that at the end of the industrial revolution, most of the birch trees were black. Researchers noticed that, over time, there had been a change in the proportion of each type of moths. White ones were the majority before industrialisation, and black ones a minority. These numbers got reversed as the trees became black. In this example, the selective pressure corresponds to the predation by birds, in combination with a change in the habitat.

Answer 63

biotic and abiotic

Answer 64

climatic (eg white fur of snow leopards to hide in white snow0 habitat (eg camouflage to hide in leaves etc) substrate (eg transition between aquatic and aerial environment. Here, organisms (e.g. razor clams) have adapted to a transitory environment, so that they can live under water but also survive when the water retreats.)

Answer 65

food (e.g. Darwin finches); predators; diseases; other species living in the same environment (e.g. hyenas who specialised in scavenging and group-living to compete with lions); conspecifics (individuals from the same species).

Answer 66

in situations where individuals are attracted to each other (e.g. reproduction) and when individuals compete with each other (e.g. dominance, feeding competition, mating competition, etc…).

Answer 67

natural selection sexual selection genetic drift

Answer 68

Genetic drift occurs when a parental population suffers from a bottleneck (only few individuals survive), like after a volcanic eruption. This bottleneck randomly selects few individuals which then compose the parental population of the next generations, leading to a different distribution of characters in the population, as compared to the original population before the bottleneck event.

Answer 69

variation in traits heritability of traits selective pressure

Answer 70

both behaviours have a genetic component, but environment affects the expression of these behaviours

Answer 71

ancestral environment, a developmental environment, an immediate environment

Answer 72

developmental environment and genes

Answer 73

the evolutionary past of a species, at the population level, determines the genotype (the assemblage of different genes which have been selected throughout the evolutionary history of a species). Together, genes and developmental environment (which can be for example, parental care, or viviparous gestation) determine the ontogeny. In turn, the developmental schemes of an individual will determine, for example, how the brain functions, how organs function, and all the hormonal system. Those are directly responding to immediate stimuli, or immediate environment.

Answer 74

behaviours are adaptations enabling individuals to maximise their fitness

Answer 75

behaviours are seen as being optimal and conditional on the current environment. The optimal aspect of a behaviour is measured by measuring the costs and benefits of such behaviour. When benefits outweigh the costs, this behaviour is maintained. Conditional means that a behaviour responds to the current needed conditions and environment However, behaviours can be constrained, in particular by phylogeny - some behaviours or physical traits are issued from a long evolutionary past, they show a strong inertia and they don’t respond to current local conditions, but rather to past environmental conditions.

Answer 76

species close to each other tend to have similar characteristics; that when the phylogenetic signal is strong, closely related species exhibit similar traits; biological similarities decrease as the evolutionary distance between species increases. Some traits, either biological, physical or even behavioural are constrained by phylogeny

Answer 77

Kamilar & Cooper, 2013 looked at phylogenetic signal across 31 traits in primate species. High signal for brain size and body mass. (brain size of a given species is closer to the brain size of related species, even if local environment differs.) Moderate signal for canine sexual dimorphism and for territoriality. Low signal for traits related to social systems and sociality, such as group size and group composition

Answer 78

previous studies had showed that some primate social systems have a strong phylogenetic component eg Eulemurs: similar social organisation characteristics independent on local habitat conditions Fleagle & Reed, 2013 This variety of contradictory results shows that we need more research to understand the influence of ecology and evolutionary past on social systems.

Answer 79

``` Competition for food Competition for mates Competition for space Disease transmission Infanticide ```

Answer 80

leprosy in wild chimps in Tai National Park and in Cantanhez National Park Hockings et al. 2021 determined it was caused by M. leprae and followed the disease progression of advanced leprosy - may be from contact with humans

Answer 81

Searching for food Mating opportunities Reduce predation risks (dilution/ confusion effect) Friendships – social bonding Competition with other groups (eg Gombe Chimpanzee War as described by Goodall 2010) Social learning opportunities

Answer 82

its social structure, determined by size and composition of a group as well as social organisation

Answer 83

Social organisation is defined by how the individuals are organized, which is determined by the patterns of spacing, by agonistic and affiliative social interactions, by philopatry (whether one or both sexes remain in their natal group), and by dispersal (whether one or both sexes move to a new group to reproduce)

Answer 84

solitary dispersed social system

Answer 85

adult male's territory overlaps the territory of one or more adult females, but each individual forage alone and maintains social contact through vocal and/or olfactory communication often nocturnal, foraging at night and sleeping in trees during the day. The mating system in these primates is usually polygynous

Answer 86

galagos, lorises, some lemurs, some tarsiers, and orangutans. Orangutans are the only anthropoid primates with a solitary social system, and they are diurnal

Answer 87

one adult male and one adult female form a small social group and defend a territory against other pairs usually monogamous (though extra-pair copulations have been observed) the male usually participates in offspring care (unusual for males in mammals)

Answer 88

This social system is found in Titi monkeys, owl monkeys, some callitrichids (marmosets and tamarins), and many hylobatids (gibbons and siamangs)

Answer 89

characterized by cooperative breeding, where only one dominant female breeds, and other individuals help in raising the offspring. the dominant female suppresses the reproduction of any subordinate females via aggression and/or pheromonal (olfactory) signals. Usually there is more than one breeding male, thus the mating system is polyandrous, a rarity among mammals. Some or all of the individuals in these groups participate in offspring care and this social system is thus often called cooperative polyandry.

Answer 90

many marmosets and tamarins

Answer 91

i.e. harem system - one of the most common primate social systems

Answer 92

A single resident adult male defends a group of usually philopatric related females from other males and, while his tenure lasts, that single male enjoys exclusive mating access to those females, resulting in a polygynous mating system. These groups are always at risk of takeover by non-resident males, who typically form all-male groups, or bachelor groups, while awaiting their chance to become a resident male.

Answer 93

infanticide ``` bringing the mothers back into oestrus (sexual receptivity) sooner than they would have otherwise ```

Answer 94

due to high male-male competition in these species, strong sexual dimorphism between males and females is observed

Answer 95

most colobine monkeys, most guenons, patas monkeys, howler monkeys typical of most gorilla populations.

Answer 96

multiple individuals of each sex form large social groups in which the mating system is usually polygynandrous These are the largest groups of primates, and usually quite complex socially, with differentiated social and kin relationships among group members. In most of these species, females are philopatric and males disperse. The fact that females stay in their natal group allows the construction of female dominance matrilines

Answer 97

living with many reproductive males results in females presenting exaggerated sexual swellings when they are receptive, to confuse paternity, to reduce male coercion and potentially to bias paternity toward dominant males.

Answer 98

d macaques, most baboons, vervet monkeys, mangabeys, capuchins, squirrel monkeys, woolly monkeys, and some colobine monkeys, as well as some lemurs - most notably the ring-tailed lemur and sifakas.

Answer 99

less cohesive than typical multi-male multi-female groups. occupy very large home ranges and individuals form temporary sub-groupings and foraging parties that split and merge over time, depending on changes in resource availability and female reproductive condition. typically characterized by female dispersal and male philopatry

Answer 100

chimpanzees, bonobos, spider monkeys, and some other ateline monkeys

Answer 101

multi-level society (AKA hierarchal or modular society) These multi-level societies characterize hamadryas baboons, geladas, snub-nosed monkeys, and a few other mammals eg elephants

Answer 102

the one-male unit (OMU), the band, the troop or herd

Answer 103

OMU is the reproductive unit and consists of one "leader" male, sometimes a follower male, and several females

Answer 104

the band is the ecological unit that forages and sleeps together

Answer 105

the troop or herd is a temporary aggregation at a sleeping site or foraging area

Answer 106

. In hamadryas baboons, there is a fourth layer between the OMU and the band, the clan, which consists of OMUs and bachelor males linked by social bonds and possibly kinship among males.

Answer 107

bachelor males join together to form all-male groups

Answer 108

usually polygynous (dominant male from OMU have priority of mating access over several females), OMUs are always at risk of takeover by bachelor males, who may commit infanticide after taking over females with young infants

Answer 109

through aggression or age

Answer 110

Often, hierarchies among females are separate than hierarchies among males, who all are dominant over the females

Answer 111

eg having a better access to food resources. time spent by female vervet monkeys at feeding sites as function of their rank: High ranking females manage to spend more time per food patch than subordinates. Similarly, in the same population, high ranking females enjoy spending more time foraging and feeding without having to move places, while subordinates are moving much more while foraging, probably because of displacement by higher ranking individuals

Answer 112

Getting more food is important for reproduction, as it guarantees a better physical condition for pregnancy, hereby consisting on indirect fitness advantages.

Answer 113

survival; reduced IBI van Schaik (1999) found a dominant female was more likely to survive at any given age General biological principle: survival decreases with age. Effect of rank: higher ranking females are more likely to survive than lower ranking ones

Answer 114

better body condition, but also to a reduced vulnerability to predation due to a higher centrality in the group.

Answer 115

in Macaca nigra (the selfie monkeys), higher ranking is associated with a better survival of infants No matter the rank of females, living in a large group is beneficial for the infants, probably due to reduced vulnerability to predators. Also, living in times of high rainfall increases infant survival, due to better food availability. higher ranking females enjoy a higher infant survival than lower or middle ranking females

Answer 116

Wright (2020) Inter-birth intervals are shorter for high ranking females.

Answer 117

high ranking males sire more offspring than lower ranking males Alberts (2006)

Answer 118

No eg in some species it may be a better strategy to increase the length between each birth, to make sure that the current offspring survive, while in other species reducing the interval between birth corresponds to a fitness advantage.

Answer 119

In this theory on infanticide, infanticide is considered a pathological unusual behaviour, which occurs in conditions of human disturbance, and in conditions of high population density. in high population density, infanticide is a way to regulate populations

Answer 120

If this theory is true, we should expect that infanticide occurs only in populations living in high population density and in areas of high human disturbance. However, data reveal that this theory is not valid, as infanticide occurs also in low population density, and is common in natural populations not disturbed by human encroachment.

Answer 121

Proposed by Hrdy infanticide is an adaptive strategy that increases male reproductive success

Answer 122

increases the speed of reproduction, in particular in species with female lactational amenorrhea and in species where males tenure is short due to high turnover of alpha position. Once an infant is killed, females, who were not fertile with a lactating infant, resume cycling and thus are immediately available for reproduction. Second, infants of other males should be targeted, so it should be done by new males, and without prior mating by these males with the targeted female. This goes in link with short-male tenure in species where males’ turnover is common. third, it should occur in species where the chances to sire the infants are high, so in species with only one adult male, or by dominant males These predictions are found to be true in the data

Answer 123

n in species with only one adult male, as well as in species with several males but only one reproductive adult male like howler monkeys. Hirawai-Hasegawa, 1988

Answer 124

females can confuse the paternity, ensuring that the males don’t know whether they are or not the father Increasing association with males

Answer 125

Promiscuous mating Synchrony of reproductive cycles Post partum oestrus

Answer 126

female promiscuous mating to increase paternity confusion

Answer 127

When several females cycle together, the chances of the alpha male to be the father are reduced. Given that this male is supposed to be the only reproductive male, it means that females actually mate with other males. In fact, when several females are receptive in the same time, it is impossible for a single male to keep access and guard these females. So, cycle synchrony helps confusing paternity

Answer 128

in species where a post-partum oestrus is present, lactation is reduced and infanticide does not occur. While in species where lactation period is longer and don’t present post-partum oestrus, infanticide is common. This study showed that a reduction of lactation period is necessary in order to develop of post-partum oestrus, which is costly in energy to produce, but it drastically reduces the risks of infanticide

Answer 129

Confusing paternity is a strategy that aims at protecting the current investment in reproduction for females, by reducing the possibilities that their current infant gets killed

Answer 130

study on baboons once an infant is born, females increase their time in proximity with males, who most likely are potential fathers, to search for protection against other males. In contrast, after the death of an infant, they decrease the time spent in proximity, as if they don’t need protection anymore. increasing proximity with males consists on a way to protect the current investment in reproduction.

Answer 131

increased association with males This increase of male-female association as a form of protection against infanticide is thought to be a strong driver of the formation of pair-bonds and monogamic social systems

Answer 132

simply to reproduce with a new male after the death of an infant (then giving priority to the next reproductive investment). This behaviour occurs in gorillas, who live in one-male systems with several females. When a new male takes over the group and kicks out the current male, the babies get killed and all the females reproduce with the new male

Answer 133

the formation of long lasting, stable and reciprocal relationships between individuals of the same group (i.e. friendships)

Answer 134

No There are increasing evidence in primates, but also in other species like horses, killer whales and humans, that forming friendships carries substantial fitness advantages.

Answer 135

female baboons form social bonds and associate more with related individuals, which makes sense from a kin selection perspective females who are more social, who have more long-lasting social bonds increase the chances of survival of their offspring In the same baboon population, t females with long-lasting stable and strong bonds have better chance to survive

Answer 136

probably due to a higher centrality in the group, better support by friends during aggression, a reduced stress and a reduced probability to be eaten by a redator due to higher centrality

Answer 137

We are able to obtain such long-term data on female baboons because they remain in their natal group, while males disperse. Yes - in wild chimpanzees, where males stay in their natal group, we can study the long-term effects of friendships

Answer 138

In male chimps, subordinates who form strong bonds with the alpha male have better chances to become father. Here, tolerance with friends and long-term reciprocity in cooperative action probably plays a big role.

Answer 139

to reinforce their position in the hierarchy, also to undertake collective actions such as hunts and border patrols.

Answer 140

In male chimps, individuals who are better connected - who form coalitions with more individuals - have more chances to sire offspring. Also, interestingly, this study showed that coalition partners are carefully chosen: males pick partners who are not involved in other coalitions, suggesting a form of trust with partners.

Answer 141

o an evolutionary reproductive response to a certain type of life history traits, such as a short lifespan and high mortality, in which the best reproductive strategy consists on investing in numbers of offspring but not investing into any form of intense parental care.

Answer 142

K selection occurs in situations where lifespan is long and mortality is low. In this case, the best reproductive strategy is to invest less in numbers of offspring, but rather spend available energy in investment in parental care or in current development.

Answer 143

long-life plant species are under K selection the is no parental care stricto-sensu, even if growing protective parts around the seeds can be considered as such investment, but a large part of the energy available is devoted to the current development.

Answer 144

yes - eg humans, also between sexes Females are under K selection while males are under R selection. Males produce a lot of spermatozoids with little energy reserves, while females produce few ovules with a lot of reserves.

Answer 145

by intimidating, deterring or defeating same sex rivals

Answer 146

the competition for sex between members of the same sex.

Answer 147

by making an individual attractive for members of the opposite sex. acts through differing reproductive strategies between opposite sexes, herby creating sexual conflicts constraints to gain access to mating partners - mate choice

Answer 148

maximise the lifetime reproductive success.

Answer 149

males are ready to mate pretty much at any time, while females much less, since they are constrained by physiological requirements such as gestation and lactation, and by potential parental care for males, the number of available receptive females is limited, while the number of males available for females is constant. In consequence, males tend to compete to access to females, resulting in an intense form of malemale competition, while females tend to choose among potential mates

Answer 150

reproduction can be costly for females, due to gestation, lactation and maternal care for females what matters is mate choice, rather than competing with other female to access to mating partners

Answer 151

eg in e group-living lemurs where reproduction is seasonal, resulting in all females from a given group being receptive at the same time.

Answer 152

vocal apparatus (e.g. vocal sack on the throat of male howler monkeys) Orang-utan males cheek flanges

Answer 153

Male howler monkeys use long calls to deter opponents and competitor

Answer 154

Cheek flanges in orang-utans only grow at a certain stage in life, and not necessarily at sexual maturity like other sexual characters. Here we talk about developmental arrest, since the full development stops at some point to continue later. Developmental arrest is very rare in mammals, and another example of developmental arrest includes human’s wisdom teeth, that only grow much later after sexual maturity.

Answer 155

In Borneo, we observe a short delay in the development of flanges (i.e. the developmental arrest is short, they grow the flanges quite fast after maturity). In contrast, in Sumatra, this developmental arrest is much more delayed. In consequence, in Borneo, many males have already their flanges, while in Sumatra, only few males have their fully-grown flanges

Answer 156

In Borneo, males are less able to monopolize females, while in Sumatra female monopolization is easier. Monopolization means that a male will roam into the various territories of the females and will limit their access from other males. These differences in monopolization potential are associated with unstable dominance between males in Borneo, where male tenure as alpha is short. In contrast, in Sumatra, dominance is stable and male tenure longer. As a consequence of these differences in the competition between males, in Borneo, the best strategy for males is to grow fast the flanges, as it increases their chances of reproduction, given that females tend to choose only males with flanges to mate. In Sumatra, the best strategy is to wait for a dominant position to grow flanges, delaying their development

Answer 157

There is a higher sexual dimorphism in groups with only one male. The mating and social system is here a direct consequence of male-male competition, where males prevent the access to females to other males by producing long calls, enabled by the development of laryngeal sacs and other vocal adaptations.

Answer 158

Higher sexual dimorphism (based on body mass) in groups with only one adult reproductive male (polygyny), and in social systems where male-male competition is more intense

Answer 159

sperm competition

Answer 160

Since many males can mate with the females, the sperm compete with each other. This competition is reflected in the size of the testes. Allometric scaling of the size of the testes for all primate species: some species are below the curve (they have smaller testes related to their body size), while others, located above the curve, have larger testes related to their body size. Chimps are above LOBF for allometric scaling of body size to testes where as gorillas are below line Chimpanzees have large testes while gorillas have relatively small ones. males living in multi-male multi-female systems have large testes, while smaller testes are found in only-one male societies

Answer 161

Large testes reflect a high sperm | competition in multi-male multi-female primate societies.

Answer 162

resource holding potential.

Answer 163

the capacity for males to provide protection, against other males, against predators or against other groups; to provide parental care in species where males do so, like in gibbons; to provide resources, or to protect access to resources; and ultimately to provide good genes.

Answer 164

honest signals

Answer 165

Black-and-white sub-nosed monkeys, who live in multi-level societies with one-male units including a single reproductive male, have these red lip colours All males, either juveniles or adults seem to display this bright colour. However, the lip colour of one-male-units (OMU) males undergoes reddening in the mating season, whereas the lips of subadults and juvenile bachelor males become paler at that time of year. In these monkeys, the lip coloration is a badge of (group-holding) status during the mating season, with non-adults undergoing facial differentiation to avoid the costs of reproductive competition.

Answer 166

live in multi-male multi-female groups, there are greyish to greenish in colour, with black faces. However, adult males have spectacular colours on their butt. Their testes are blue and the scrotum are red. Vervet monkey males carry out the red-white-blue display: they lift their tail up to show these bright colours. more dominant individuals display more often per unit of time their bright colours than subordinate males. Since dominant males tend to have better access to mating opportunities, this signal may serve as an honest signal toward the females to show their group holding potential

Answer 167

the bright colours of mandrills, red face of Uakaris the colour patterns of Douc langurs

Answer 168

more colourful males get more mounts than less colourful ones, hereby increasing their chances to sire offspring, with brighter males being approached by females more than dull males. t females present more to brightly coloured males. So, it seems that mate choice occurs and that these bright colours have evolved under the pressure of mate choices by females.

Answer 169

bright colours are related to the health of the individual, as well as to the genetic diversity of their immune system, here relating to the idea of good genes are displayed through honest signals

Answer 170

females and males adopt different reproductive strategies to reach optimal fitness. These conflicting optimal fitness strategies concerning reproduction relate directly to the K and R selections. Sexual conflicts are embedded within an evolutionary arm race between males and females.

Answer 171

under a selection of type R, males invest in numerous gametes without energetic reserves. e. In their situation, reproduction mistakes, such as miscarriage, are extremely costly. In consequence, females are choosy (mate choice). Since the amount of receptive female is then limited, males are limited by the access to females

Answer 172

Females investment is targeted toward their current offspring. Gestation, lactation and maternal care require a lot of energy, and thus a lot of resources. Consequently, females are limited in space by resources distribution and availability. Males, who do not invest into offspring, are much limited by food resources and can search all the time for mating. Consequently, males spacing is limited by the access to females.

Answer 173

by the number of offspring they obtain Since female reproduction is limited by the access to resources, females compete with each other over these resources. Accessing to better resources enables a reduction of inter-birth intervals, hereby increasing the potential number of offspring obtained across a lifetime; better resources are associated with improved survival, with better offspring survival and with better health.

Answer 174

Since female reproduction is limited by the access to resources, females compete with each other over these resources. Accessing to better resources enables a reduction of inter-birth intervals, hereby increasing the potential number of offspring obtained across a lifetime; better resources are associated with improved survival, with better offspring survival and with better health. As a consequence of this competition for resources, females try to monopolize resources, which leads to the formation of dominance hierarchies

Answer 175

``` yes The position of a given female within dominance hierarchies is passed on to their daughters, here building matrilines (i.e. lines of female dominance passed from generation to generation), mostly to be able keep a good access to resources. ```

Answer 176

Low variance and weak reproductive skew Despite these hierarchies, and since each female is limited by resources but all manage to have offspring, among females, the variance in reproductive success is low

Answer 177

In cooperative breeders, where subordinate reproduction is suppressed by the dominant, the reproductive skew is strongly biased toward the dominant.

Answer 178

since reproductive success is limited by the access to females, there is a high variance in reproductive skew in a given group, with higher ranking males having most of mating opportunities as compared to subordinate males. Consequently, we observe a high reproductive skew in males.

Answer 179

when there are more males, less of them have a chance to mate since most mating are taken by the top ranked ones. males in their prime, between 10 and 13 years old, sire most offspring. In this population, the top sire in each year produced 24% of the infants, while 71% of troop males sired no offspring at all.

Answer 180

female defense resource defense

Answer 181

long-term associations, as in monogamous pairs or in harem systems, with only one reproductive male dominance hierarchies, as in multi-male multi-female groups, where dominant males have priority of access to the females, or where males can form short-term consortship bonds with females, and where females are receptive asynchronously coercion (where males physically force females to copulate)

Answer 182

when males attempt to bias mating in their own favour by using harassment, meaning by persistent mating attempts; or by using intimidation such as aggressive behaviour; or by forced mating when males use the force, or threat, leading to higher rates of potentially fertile mating with the female and a lower rate for other potential mates, at some cost to the female

Answer 183

Smuts and Smuts give greater importance to the exclusion of other males from mating by using the force, while the first definition focusses more on the ways forced mating are obtained

Answer 184

Coercion of females is common in orang-utans and in some baboons, among others.

Answer 185

OWM males are more coercive than NWM, which are more coercive than lemurs Mating during pregnancy, copulation calls and surreptitious mating are very common in the most coercive groups of primates, the old world monkeys

Answer 186

s the multiplicity of cycles per conception, longer mating periods and the presence of exaggerated sexual swellings.

Answer 187

sexual swellings in catarrhines

Answer 188

female dominance over males and the formation of female coalitions.

Answer 189

n chimpanzees, males form coalitions to aggress other males, while in bonobos females form coalitions against male aggressions.

Answer 190

Femalefemale coalitions are very common, much more than male-female and male-male coalitions. at all ages, but especially for young females, forming coalitions increases the chances to win a conflict. All of the targets of female coalitions are males, of which most (95.5%) are adult. Females never formed coalitions to attack other females. when females formed coalitions, 100% won against a target males.

Answer 191

from the males, their capacity to recognize kin (family members) and mechanisms to detect ovulation lead to high chances of infanticide, which are counterbalanced by females mating with multiple males. This strategy is then challenged by males who use mate guarding, by an intense sperm competition, by intimidation, punishment and coercion; these male behaviours are then counteracted by females who increase the length of mating periods, conceal their ovulation, show synchronous oestrus and form female coalitions

Answer 192

carbohydrates

Answer 193

tannins caffeine alkaloids

Answer 194

a) from fruits, seeds and gum. | b) extracted from seeds an animal prey

Answer 195

from leaves, in particular young leaves which are high in protein content and low in fibre content. Proteins also come from arthropods, such as insects and spiders, and from other types of animal prey

Answer 196

licking earth elements, such clay or rocks, to get essential salts from them Geophagy is a common behaviour for many species of animals (e.g., community of parrots in Peru). Several species of primates have been observed licking rocks or eating clay (e.g., macaques and mangabeys).

Answer 197

in food, in tree holes and in natural water holes In some environments, where water on the ground is rare, some primates like chimpanzees in Comoé, a savannah National Park in Ivory Coast, have developed a tool technology to access to water in tree holes.The tip of a branch is chewed on the produce a type of sponge, enabling the individuals to dip into tree holes to extract the residual water. Other chimpanzee populations use leaves to make a sponge out of it and to extract water.

Answer 198

Tools, such as long sticks, can be used to extract underground honey, as it has been observed in Gabon. also extraction of termites and ants use of wooden or stone hammers to crack nuts

Answer 199

These nut cracking techniques have been used for thousands of years, and researchers studying these techniques in wild chimpanzees can see in other extracting techniques, such as pounding techniques, examples of proto-cultures that most likely preceded the use of wooden or stone hammer to extract food

Answer 200

adapted colour and stereotypic vision Since they see in three or two colours, they can distinguish the various degrees of ripeness of fruits, and with their forward-facing eyes, they see in 3D which enable them to move in the trees and capture moving preys. A certain number of morphological adaptations facilitate food extraction and processing, such as teeth shapes adapted to certain diets, or the specialized finger of the aye-aye to extract gum and insects under bark trees and tree holes.

Answer 201

. Fruits are a great source of sugar and carbohydrates, but the problem when you rely a lot on fruits is that their production is relatively patchy also seasonality in production variability between years - highly unpredictable

Answer 202

seasonality in production is, in some parts, due to variation in rainfall and temperature, even in tropical areas, but also due to natural cycles of production of each species of tree

Answer 203

For some months not so many species are fruiting, while in other months a lot are fruiting. This then has consequences on the dynamics of primates that rely on these sources, and it makes these resources easy to monopolize

Answer 204

protein fibre tannins, which are hard to digest developed a specialised stomach with several chambers helping the digestion.

Answer 205

leaves are relatively evenly distributed: leaves are produced in large quantities, which makes them hard to monopolize. In addition, leaves show a relatively weak seasonality, or no seasonality at all

Answer 206

protein | fat

Answer 207

their leaping mode, great vision and their well-developed auditive system

Answer 208

False | Since arthropods are a great source of protein and fat, most primate species eat insects and arthropods

Answer 209

these two monkeys, which are sympatric (i.e., they live in the same forest), occupy different parts of the forest: blue monkeys, larger than the lhoest monkeys, occupy the top part of the canopy, while lhoest monkeys occupy the lower strata.

Answer 210

group living

Answer 211

Once in group, chances to be caught by a predator are reduced due to the higher number of potential targets (dilution effect), due to a confusion effect when individuals flee in many directions (confusion effect), and due to alarm systems given by conspecifics

Answer 212

Primates have also learned to adapt to the risk inherent to predation by using typical sleeping habits, such as building nests high in the trees for the apes (except for gorillas who do their nest much lower due to their weight, but their large body size also protects them against predators, even if the youngsters build nests higher than adults) Other primate species, like some lemurs in some regions of Madagascar and gelada baboons, sleep on cliffs to escape predators

Answer 213

deterrence of predators s and to inform conspecifics from their group, as well as other animals in the surroundings such as other primates living in polyspecific association

Answer 214

small antelopes associate with terrestrial primates like mangabeys, probably for taking advantage of the number of individuals to detect and avoid predators

Answer 215

``` Snakes Birds Cats Humans Fossa Komodo dragons Dogs ```

Answer 216

Arnold & Zuberbuhler, 2006 Putty-nosed monkeys possess a referential call system. Different call for eagle and for leopard

Answer 217

when hearing or seeing a leopard, guenons and vervet monkeys use a referential alarm call and they tend to climb into trees, or to climb higher for guenons. When hearing or seeing an eagle, these primates use a specific referential call and they rush toward the ground or in bushes for vervet monkeys, while guenons go lower in the trees, under big branches. These primates also respond differently, acoustically and behaviourally, in presence of a snake

Answer 218

a heuristic approach that attempts to explain all forms of primate social organisation, would it be grouping patterns, dispersal patterns and even social relationships.

Answer 219

the idea that aggregations of animals could occur simply as a result of animals’ attempts to avoid predation by putting conspecifics between themselves and the predator -

Answer 220

the idea that the sex investing less in offspring evolves to compete for access to the other sex, while the sex that invest a lot in offspring, in term of gamete production, gestation, lactation and parental care, is constrained by energy requirements and thus compete for food.

Answer 221

Causal relationships between food distribution, predation, mating strategies, social organisations and relationships

Answer 222

Crook & Gartland, 1966 proposed five grades, separated by group sizes, mating structure, male dispersal, sexual dimorphism, territoriality, but also with variation in grades based on differences in habitats, diel activity (either diurnal or nocturnal) and diet This model sets the bases for further models emphasising on predation and food as determining social organisations. In this model, social conditions present in each grade were mostly based on ideas of sexual selection and male-male competition for access to females.

Answer 223

grade one includes most of Prosimians, living in forest habitats, eating insects and being nocturnal. Here, the assumption is that insects are easier to prey upon for solitary nocturnal individuals.

Answer 224

Grade 5 includes species living in the savannah and being diurnal. Here the assumption is that, in savannah habitats, there is enough food to sustain large groups and that large predators oblige primates to aggregate in these large groups

Answer 225

Habitat: grades increase from closed to open, going from forest habitat toward savannah and grassland. Same as for diel activity: it starts with nocturnal species, then crepuscular in grade 2 and then diurnal. Group sizes also increase from grade 1 to grade 5. Same as for sexual dimorphism, from none to high in grade 5

Answer 226

Eisenberg, Muckenhirn, and Rudran 1972 demographic conditions (maturation and philopatry of natal males) are responsible for observed transitions from single males to multiple males in social groups

Answer 227

the troop growth model, which assumes that the optimal social organisations at moderate population density are one-male units, with a founder male aggregating around few females. The troop grows by recruitment yielding a subgroup of juveniles and a beta male that is subordinate to the alpha male who can be his father. At greater densities, younger males may form a peripheral subgroup of their own that has no direct contact with the basic subgroup of mothers and their young. Although the troop now appears to be multi-male, Eisenberg and colleagues propose that it would be more correct to consider it an age-graded-male group. Splitting of the new unstable troop can lead to the original uni-male configuration

Answer 228

starts with a solitary pattern, where adult males and females have separate centres of activity and encounter infrequently. The extended ranges of the males overlap with the home ranges of the females. Then, there is a transition toward family groups, where a bonded pair and their subadult offspring travel as a homogeneous unit in an exclusive home range. Family units transit toward uni-male groups where an adult male is in periodic contact with a cohesive group of adult females and their offspring. These uni-male groups with periodic contact transit toward uni-male groups with relatively constant contact with a cohesive group of adult females and their offspring, which themselves transit toward multi-male groups, which is a cohesive group of several adult males and females with their offspring

Answer 229

population density

Answer 230

the ecological model emphasizes the fact that females are the ecological sex, in the sense that females distribute themselves around food resources. For Wrangham, predation doesn’t play an important role in female distribution and primate social organisations.

Answer 231

Wrangham considers that there are 2 types of female groupings: female-bonded groups and non-female bonded groups. Food is at the base of differences between these two groupings, with clumped food such as fruits for female bonded, and evenly distributed and abundant food such as leaves for non-bonded females. In turn, these types of food lead to an increase of feeding competition for females when they rely on clumped food, while no competition occurs when females rely on leaves. To overcome this competition, females aggregate in large groups to compete with other groups in frugivore species, while in folivore species, females will aggregate only around males to search for protection against other males. So here, grouping in female bonded groups is due to between-group feeding competition, while female grouping in non-bonded groups is due to male mating strategies such as harassment and coercion. Within the group, in female bonded groups, inclusive fitness benefits lead to females giving benefits to their relatives, such as their daughters, while no inclusive fitness benefits are expected in folivore non-bonded groups. Inclusive fitness benefits make female stay in their natal groups on one side, while in non-bonded groups females disperse. And in turn, due to high within-group competition and inclusive fitness benefits, differentiated dominance and grooming relationships are expected in female bonded groups, with the formation of matrilines following kin structure (daughters inherit the rank of their mothers), with dominants receiving more grooming than subordinates and having priority of access to food. Not such differentiated dominance and grooming relationships are expected in non-bonded female groups

Answer 232

: In this model, the influence of food distribution is considered to differ between periods of food abundance (here "Growth diet") and periods of food scarcity (here "Subsistence diet") Growth diets in large high-quality patches, where there is a finite number of feeding sites, favour female-bonded groups. Subsistence diets in uniform, continuous patches, in which there is effectively an unlimited number of feeding sites, neither favour nor disrupt group-living. Females therefore sort themselves into groups competing against other groups.

Answer 233

Food clumped (fruits) Increased competition among females Females form larger groups to overcompete smaller groups Inclusive fitness benefits: females related within the group Philopatry of females Differentiated dominance and grooming relationships

Answer 234

Food evenly ditributed (leaves) No competition Female disperse from natal group No differentiated dominance and grooming relationships Non-female bonded Females gather around males for protection against other males No inclusive fitness benefits

Answer 235

: food distribution is the main basic determinant of female grouping and female social relationships. Food differs in their distribution, in their quality and in patch sizes. Defensible high quality food leads to group formations to fight other groups, defensible but of variable quality food leads to in-group dominance hierarchies. And in both situations, females stay in their natal group (female philopatry). When food is in small high quality clumps such as insects or uniformly distributed such as leaves, competition between groups is less intense, and dominance hierarchies within-groups are weak, leading to female dispersal.

Answer 236

van Schaik argued that multi-female groups were initially favoured by predation pressure. However, van Schaik agreed with Wrangham that food competition determines female social relationships within and between groups. van Schaik introduced for the first time the concepts of contest and scramble competition

Answer 237

contest competition scramble competition

Answer 238

resources are clumped, so resources are scarce and valuable, hence resources are worth fighting for, because they can be monopolized, resulting in strong direct competition.

Answer 239

resources are dispersed like insects or evenly distributed like leaves. Thus, individuals just have to scramble to get enough, resources are not worth fighting over because they are not monopolizable, resulting in the absence of direct competition.

Answer 240

within and between-group food competitions 4 types (Type A-D)

Answer 241

When scramble competition predominates within groups, females in multi-female groups would develop individualistic, egalitarian dominance hierarchies

Answer 242

When contest competition predominates within groups, groups of female relatives would develop nepotistic, despotic dominance hierarchies

Answer 243

Under intermediate or high predation pressure, when foods occur as in Type A, scramble competition would be expressed within groups while contest competition would be expressed between groups (because larger groups suffer less from predation than smaller groups), leading to philopatric females and egalitarian dominance hierarchies

Answer 244

under low predation pressure, when population density is high relative to the food supply, contest competition between groups would be favoured and female relationships within groups would be nepotistic but with egalitarian dominance hierarchies

Answer 245

He did not consider scramble competition between groups sufficiently important to affect female social relationships

Answer 246

They assigned new labels to Types A–D, based on the intensity of contest competition. Importantly, for the first time in the field of socioecology, a distinction was made between “ecological models” and “socioecological models” because it also incorporated the social component of infanticide avoidance

Answer 247

``` A was now Dispersal–Egalitarian, B was Resident– Nepotistic, C was Resident–Egalitarian, D was Resident–Nepotistic–Tolerant, based on the intensity of contest competition ```

Answer 248

They proposed that the risk of infanticide was sufficiently strong that under the conditions of low predation and low competition, females would disperse from their natal groups to form strong associations with protective males, leading to the dispersal–egalitarian groups (like Wrangham’s non-female-bonded type).

Answer 249

Dispersal-egalitarian occur when within and between group competitions are low, resident-egalitarian when within-group competition is low but between-group competition is high

Answer 250

resident-nepotistic when within-group competition is high but between-group is low, and resident-nepotistic-tolerant when both within and between-group competitions are high.

Answer 251

when dispersal is costly, females do not disperse; high predation risk makes females grouping together; large group size leads to strong within-group contest competition. This in turn affects female dominance relationships: females form coalitions with kin against other females (nepotistic social relationships). This in turn prevents female dispersal, which means that groups grow above the optimum size before they eventually split. Once females are in this cycle they cannot easily convert to the opposite strategy of low within-group competition, egalitarian relationships, female dispersal and small (optimum) group sizes

Answer 252

a) when there is no dominance hierarchy, female dispersal is possible and the benefit of excluding females from resources is low; b) when dominance hierarchy is high with strong kin support, such as forming coalitions with family members, female residence is necessary and the benefit of excluding other females from resources is high.

Answer 253

the attempt to encompass all observed social systems within one single framework is an illusion

Answer 254

particularly regarding the effect of infanticide risks on female resident groups and the effect of scramble between-group competition. Thierry lists a series of inconsistencies between what is observed in primates and what the model should predict such as rates of agonistic interactions in several populations not being affected by habitat variations in the patchiness of food supplies, or that female dispersal is associated with clear dominance hierarchies and aggressive encounters between groups in some species, like chimpanzees

Answer 255

He based his argument on the fact that some traits are correlated within closely related species living in different habitats and ecological conditions. He used macaque species to illustrate his point: some species of macaques show a high degree of intolerance, strong dominance hierarchies and high nepotism, like rhesus macaques and Japanese macaques. While other species of macaques (e.g., black-crested macaques and Tonkean macaques) are relatively tolerant, with a relaxed dominance and a weak influence of kinship. All these macaques have similar dispersal systems, similar type of diet, similar multi-male multi-female groups, and they may even live under similar climatic conditions. For Thierry, this weakens the determinism of ecological conditions on social relationships and for him similar levels of tolerance between Tonkean macaques and black-crested macaques are due to the fact they are closely related species, so he argues that phylogenetic constraints play a major role in conservation of dominance systems

Answer 256

some strategies can be adaptive from an ecological perspective, while other strategies may be adaptive from a social perspective, counterbalancing and opposing the advantages due to the ecology.

Answer 257

high contests can be advantageous because it reduces the number of conflicts and shortens duration of conflicts, but also low contests can be advantageous because it increases conflicts resolution and reduces the severity of wounds; also, high maternal restrictiveness protects infants against dangers, but alloparental care (care provided by other individuals than the parents) increases the number of protectors.

Answer 258

No evidence of a relationship between today‘s ecological conditions and dominance style (Menard, 2004)

Answer 259

the dispersal/foraging efficiency model. T Isbell, 2004 perspective of females categorizes five types of females: stingy mothers, generous mothers, facilitators, indifferent mothers and incomplete suppressors.

Answer 260

a) Stingy mothers are found in species where only one female reproduces, females don’t share the resources within their home-range, and females disperse from their natal groups. Gibbons, pottos, tarsiers and lemurs fall in this group b) Generous mothers are found in species where reproductive females are solitary, but they share resources within their home-ranges (so there is home-range overlap) with other females. In general, other females are daughters or related females like aunts and nieces. Orang-utans, mouse lemur, and galagos would fit here c) Incomplete suppressors are small groups of kin females (related females), where females disperse when chances of in-group reproduction are limited; red howler monkeys and some lemurs would fit in there.

Answer 261

a) Facilitators correspond to mothers facilitating their daughters’ reproduction, by forming matrilines and where it is then beneficial to not disperse. These are equivalent to female-bonded groups of Wrangham. Yellow baboons and macaques are in this group. b) indifferent females occur when food does not limit females, where females may disperse or stay in their groups. Langurs and colobines fall in here

Answer 262

dispersal costs are at the base of it. Ability to expand the home-range is the next condition, as well as goal direct traveling modes. Foraging efficiency and female-female feeding competition is then considered to categorize the different strategies

Answer 263

Feeding efficiency includes only the time and energy spent during feeding; foraging efficiency includes the costs of both feeding and moving during the day

Answer 264

Small groups have a better feeding efficiency than large groups, meaning that their intake per minute is higher. Since there are fewer individuals, each of them gets more than if they were living in a higher group. However, foraging efficiency shows no difference between groups of different sizes, illustrating that moving between food patches seems to be higher for small groups than for large groups or that large groups have access to larger patches of food than smaller groups. Stacey, 1987

Answer 265

the small group spend more time foraging than the larger group Given that large groups have more individuals, they most likely deplete food resources much faster than the small group so large groups have to compensate by moving more Ruiter 1989

Answer 266

, a cost inherent to a large group is that, when food is scarce, individuals have to rely on food of poor quality

Answer 267

Ruiter (1989) showed the larger group relies more on poor and risky food (pith of palm stems and snails) during the dry season. Risky because snails are found on the ground, where predation risks are higher. For these frugivore species, being too big as a group doesn’t seem to be so good

Answer 268

as for baboons and capuchins, larger groups spend less time feeding most likely due to competition for food between a high number of individuals larger groups do not travel more than smaller groups, and the costs of traveling are higher for intermediate size groups. Grueter 2018

Answer 269

The largest groups have the have the highest feeding efficiency Grueter (2018) showed gorillas living in large groups gain advantages when it comes to compete with neighbouring groups so the increased efficiency of larger groups may be explained by advantages in intergroup contest competition

Answer 270

The largest group had much lower home-range overlap than the other study groups which may be due to groups avoiding one another as a result of male mating competition Grueter et al., 2018

Answer 271

living in groups is beneficial from a foraging perspective, but increasing group size lower these advantages by increasing competition. advantages of large group size depend on the type of food - gorillas being folivore as compared to frugivore baboons and capuchins - and on the intensity of between-group competition (as in this gorilla population).

Answer 272

by hiding from predators, by small and cryptic; by living alone, by living at night, by forming polyspecific associations (i.e., associating with other species to benefit from their vigilance, from their alarm calls and from their number).

Answer 273

when predation risks are high, primates live in larger groups (Hill and Lee, 1998) as risk increases number of males increases (Van Schaik & Hoerstermann, 1994)

Answer 274

compared three folivore primate species - howler monkeys, colobus and langurs. Monkey eating predation by crowned eagles is also compared, showing that langurs are much less predated than howlers and colobus. When the number of adult males is compared, it reveals that species that have a higher risk of predation also have more males in their groups (Van Schaik & Hoerstermann, 1994)

Answer 275

large groups are easier to detect than small groups body size: when the preys are large and conspicuous, they are easily detected by predators, consequently it pays to form large groups. When preys are small and discrete, they are harder to be detected by predators, so they tend to be cryptic or solitary.

Answer 276

The large group is less vigilant than the small group; the small group never goes to the ground and occupies higher strata than the large group. large group had a lower feeding efficiency than the small group, but here anti-predation advantages counterbalance the feeding costs Ruiter, 1986

Answer 277

small group spends more time in the higher strata than does the large group. Predation risk is higher in lower strata (terrestrial predators), so the large group can afford taking more risks than the smaller group, by occupying the riskier strata.

Answer 278

To avoid infanticide, females tend to associate with many males in order to mate with more than one male to confuse the paternity. When males are not sure to be the father, the likelihood to commit infanticide is reduced.

Answer 279

by having synchronous cycles the alpha has less chance to conceive when many females cycle, showing that they mate with other males since the alpha cannot monopolize all the females at the same time

Answer 280

, in primate species showing post-partum oestrus, no infanticide is observed, while infanticide is common in species not having exaggerated sexual swellings.

Answer 281

when infanticide risk is high, females will associate with males. eg in baboons: after the birth of an infant, females spend more time in proximity with males than before. In mirror, after the death of an infant, females do not associate anymore with males.

Answer 282

yes - females associate with the likely father chnages in association are usually associated with infant death

Answer 283

yes even though they live in harem societies females associate with the most likely father group size is highly variable within a given year due to female migration, either arriving in the group or leaving the group. These changes of group size are due to infanticide by males.

Answer 284

female transfer, in most of the cases, occurs simultaneously or subsequently to the infanticide committed on their infant , in most of cases of female transfer, females join the infanticidal male. infanticide is indeed a strong pressure for females to associate with males, either to hang out with the likely father, or to confuse paternity.

Answer 285

individual feeding rates and food quality decreases with dominance rank, and that high ranked individuals spend more time resting and socializing, while low-ranked individuals spend more time in feeding and traveling to search for food

Answer 286

White-faced capuchins are frugivore primates that live in multi-male multi-female groups, where foods are highly patched and so where within-group contest competition is assumed to be strong

Answer 287

high-ranked females aggress more and low-ranked receive more aggression High-ranked better energy intake as aggression rates increase, the difference in intake rates between dominants and subordinates increases

Answer 288

a direct consequence of the competition for high quality food

Answer 289

In vervet monkeys, high ranking individuals, particularly in females, spend less time moving than low-ranking individuals, following the prediction of high within-group contest competition in olive baboons,, high ranked individuals gain more energy and better food intake as compared to low-ranked females, but here this difference doesn’t translate in differences in activity budget.

Answer 290

low-ranked individuals have to follow the activity pace of the group, given that olive baboons who live in the savannah have a lot of big predators, obliging all individuals to follow the group.

Answer 291

individual feeding rates decrease with group size, which is confirmed by findings in mountain gorillas. large groups have larger home-ranges and larger groups have larger daily traveling distances.

Answer 292

Steenbeck & van Schaik, 2001 found In Hanuman langurs, a folivore species living in India, when home-range sizes as function of group size are plotted, it confirms that larger groups have larger home-ranges also found Longer traveling distances for larger groups Meanwhile in mountain gorillas Grueter (2018) this relationship is not linear as daily traveling length is higher for intermediate group sizes thus inconsistent (a differential in quality patch may explain this non-linear relationship, more similar to what would happen in case of within-group contest competition.)

Answer 293

Scramble competition within-group -> should support large group sizes BUT relatively small group sizes

Answer 294

small group sizes may be due to depletion of food patches, limiting group expansion; female reproductive success may be better at intermediate group size, due to increased scramble competition. infanticide risk may limit group size increase, as female disperse to avoid harassment by males, keeping group size below optimum

Answer 295

when food patches are not monopolizable. Here, home-ranges show a high degree of overlap, and the intensity of between-group competition is mostly affected by population density. observations seem to confirm this rule

Answer 296

Within-group competition increases with group size

Answer 297

Contests for clumped food lead females to make coalitions with kin

Answer 298

- Low within and between-group competition - No dominance relationships, no hierarchies - No female coalitions - Dispersal not costly

Answer 299

lemurs, most folivore species such as gorillas, langurs, howler monkeys, colobus. There are inconsistencies among folivores in term of predictions and observations, such as alliance formation in some species

Answer 300

chimpanzees and bonobos are assumed to be in this category, but chimpanzees show a high degree of between-group competition and females form a linear dominance hierarchy, bonobos have a lower degree of BGC, but also form linear dominance hierarchies among females, and females form coalitions.

Answer 301

- Low within but high between-group competition - No dominance relationships, no clear hierarchies - No long-term alliances - Coalitions for between-group competition - philopatry, stay with kin

Answer 302

patas monkeys, most guenons and mangabeys eg patas monkeys, most guenons and mangabeys

Answer 303

- High within but low between-group competition - Formal dominance relationships, linear hierarchies, submission signals - long-term alliances and coalitions with kin - costly dispersal (lose alliances) - philopatry

Answer 304

macaques, baboons, capuchins vervet monkeys. macaques show a strong phylogenetic signal in their social relationships, with varying degrees of submission and nepotism, not associated with competitive regimes, in capuchins where between-group contest competition can be very strong.

Answer 305

all Sulawesi macaques fall in this category Given these macaques showed much higher levels of tolerance than other macaques, it seems that there was a need to provide an extra category for them.

Answer 306

- High within and high between-group competition - Formal dominance relationships, linear hierarchies, submission signals - long-term alliances and coalitions with kin - philopatry - costly dispersal (lose alliances) - relatively tolerant dominance relationships, to not lose support from low-ranking when in BGC

Answer 307

acting that females are the ecological sex, since female reproductive success is limited by access to resources; males aggregate around females and so male reproductive success is limited by access to females; food types, distribution and quality lead to different competitive regimes; scramble competition limits group size; contest competition promotes kin-based alliances, food, predation and male mating strategies are important selective pressures on female grouping

Answer 308

in chimpanzees, that core area quality is associated with a better female reproductive success; that better food is reflected in better reproduction (Emery-Thompson & Wrangham, 2008) In female vervet monkeys, access to better food in females is associated with dominance and hierarchy, as dominance improves access to resources and thus improve a lifetime reproductive success. (Isbell et al., 1999)

Answer 309

less chances to conceive when more males are present in a group of wild chimpanzees male-male competition for mating, resulting in a reproductive skew where chances to sire are reduced for groups with more adult males Kutsukake & Nunn, 2006

Answer 310

alpha males have priority of access and get the highest percentage of copulations as compared to low-ranked males Stoinski et al., 2009

Answer 311

it is not clear if female social relationships are ultimately determined by ecological conditions, neither if social behaviour is so adaptive or merely just inherited from a past ancestry. Here the role of phylogenetic constraints is important, as shown in macaques

Answer 312

- Are female social relationships determined ultimately by ecological conditions - How adaptive or inert is social behaviour ? - female dispersal patterns: cause, consequence or circular effect? - role of phylogenetic constrainsts - inconsistencies between models‘ predictions and observations: Folivore paradox Prolonged social relationships between sexes outside of breeding period Aggression rates do not always match predictions (in particular dispersal patterns)

Answer 313

depending on the models, as the dispersal-foraging efficiency model presented in the previous lecture, it is not so clear if dispersal is a cause or a consequence of the social organisation and of the competitive regime, or if its embedded in a circular loop so that when ecological conditions change it is impossible to switch from one system to the next.

Answer 314

in Colobus vellerosus, a species of folivore colobus, researchers found that females show low levels of grooming, no female coalition over food and female dispersal. These parameters fit perfectly with a dispersal-egalitarian system. However, they also found that female-female affiliations were much higher than female-male affiliation, which goes against what is expected for a dispersal-egalitarian species and corresponds more to a resident behaviour.

Answer 315

affiliation among females can be a response to male harassment and infanticide risks, where coalition formation among females do not act within feeding competition, but against males, as seen in wild bonobos.

Answer 316

in multi-male multi-female mating systems, like in chimpanzees

Answer 317

It creates a strong male-male competition, which leads to a strong sexual dimorphism, as in one-male mating systems like gorillas. Male-male competition is also leading to sperm competition, as seen in multi-male multi-female mating systems, like in chimpanzees. Male-male competition also leads to a reproductive skew, where only few males get most of mating and copulations, while the majority of males never gets access to females, either within a group or within a population.

Answer 318

Lower survival in males is most likely due to the fact they take more risks, to defend a group, against enemies or predators, and due to fierce male-male competition, but also due to a more stressful life than females in species where males are caregivers, males survive longer than females. Generally, caregivers live longer as they need to live longer to look after their offspring

Answer 319

dominance | High rank increases reproductive success

Answer 320

+ it increases reproductive fitness - exhaustion - in high ranked individuals, testosterone levels are high (this is detrimental for health, in primates, humans and other mammals)

Answer 321

testosterone levels increase with dominance, and thus decrease when individuals go down the hierarchy (e.g., when they get older)

Answer 322

the length of which an individual keeps a high rank

Answer 323

Tenure length decreases as the number of females increases in the group due to high takeover and difficulty to monopolize access to females when there are many

Answer 324

while in these groups males have a longer male tenure, tenure length also decreases with the number of females

Answer 325

male breeding tenure is also shorter in species in which females breed frequently than in those where females breed less frequently.

Answer 326

allostatic load: cumulative physiological burden as individuals adjust their morphology, physiology and behaviour to transitory factors

Answer 327

In cooperative breeders, dominant individuals are more stressed than subordinates. In other social systems, subordinates are more stressed than dominants.

Answer 328

In large subadults, stress level increases as their rank increases, while in established adult males, it is the opposite: dominant males are less stressed than subordinates high ranked individuals buffer stressful events with their relationships and bonding with other males

Answer 329

via social relationships or conflict avoidance

Answer 330

sociality increases with dominance, where dominant individuals are more social than subordinates sociality predicts future dominance success males with strong bonds improve their reproductive success Schulke et al., 2010

Answer 331

subordinate friend males get mating opportunities In wild chimpanzees, political support is exchanged with mating - Duffy (2007) found mating success increases with support given to the alpha male Feldblum et al., (2021) found Wild subordinate chimpanzees are more likely to sire if they have strong bonds with the alpha male

Answer 332

male reproductive skew is actually not so skewed In Barbary Macaques, it was found that there is very little reproductive skew as most males end up copulating with females, due to these coalitions

Answer 333

the level of within-group competition (WGC) and the level of between-group competition (BGC)

Answer 334

In one-male groups, like most gorilla populations, resident males expulse natal males from the group and prevent any immigration, resulting into a low WGC among males, but a high BGC

Answer 335

males form systems of dominance and hierarchies and males also tend to prevent the arrival of new males. This results into a high WGC but also a high BGC.

Answer 336

w in situations where female choice is stronger than male-male competition, as in polyandrous and monogamous mating systems (also true for humans) when female reproduction is synchronized, which results in females not being monopolized.

Answer 337

Young males get most of the mating, tenure can be quite short, and they often have one-sided relationships (asymmetric relationships where the subordinates give more than they receive). This results in a certain reproductive skew (e.g. in baboons and rhesus macaques, where most of mating are obtained by young males in their prime) Old individuals get less mating opportunities but they also change the way they interact with other individuals: they form more friendships with females and have more equal and mutual social relationships with other males.

Answer 338

When it comes to aging, one would think that older males are less strong than younger ones but it is not necessarily the case in rhesus macaques, the number of offspring sired, as function of age: most offspring are sired by young males in their prime, but body mass is not changing over time

Answer 339

not necessarily a question of physical strength, but rather related to the capacity to form coalitions with young partners

Answer 340

, in wild chimpanzees, of the number of mutual friendships as function of age: mutual friendships increase with age, while the number of one-sided relationships decreases with age. Rosati et al., 2020

Answer 341

False | In most primate species, males leave their natal group at sexual maturity.

Answer 342

Males can either enter a new group at the bottom of the hierarchy, for multi-male groups, or they can try to take over a group of females by excluding the resident male, and killing all the babies, like in one-male mating systems

Answer 343

No Since dispersal is costly and dangerous, because males don’t have the protection against predators that the group offers, it is common to observe male dispersal in cohorts, sometimes brothers, who form bachelor groups

Answer 344

to avoid inbreeding within a group

Answer 345

. There are no primates where both males and females stay in their group. there are few species where both males and females disperse, as in monogamic species like gibbons.

Answer 346

kinship the place in the hierarchy attained after arrival, and on other males arriving.

Answer 347

Gerber (2016) studied long-tailed macaques and found Males who have many family members in the group, the plain line, are more likely to postpone their next departure than males who have less relatives in the group

Answer 348

The timing of secondary dispersal here depends on the place in the hierarchy attained after arrival, and on other males arriving. If a low rank is achieved in a new group, males emigrate again once another male arrives. Here, these males do not reproduce but they suffer of no injury. If a high rank is achieved in a new group, these males emigrate again, but later, not matter if new males have arrived. Here, they achieve a high reproductive success but suffer injuries when they get kicked out.

Answer 349

chimpanzees, bonobos some spider monkeys In these societies, young males have to climb up the hierarchy rather than dispersing

Answer 350

kinship, between brothers and half-brothers males compete with other groups to get the best habitats that are supposed to attract more females

Answer 351

Poor evidence for this female attraction effect has been found so far, at least in chimpanzees and bonobos In bonobos, between-group competition is low and females are codominant. In these patrilocal societies, within-group competition between males takes place over access to females, with the formation of dominance hierarchies, coalitions, mate-guarding and female exert their female choice on the males

Answer 352

In pair-bonded species, the rule is that one male stays with one female, protects the infants and is territorial (typical monogamous system). However, if BGC increases, due to increase of population density or reduction of habitat quality, a primary male has to tolerate other males, here cooperatively defending the range against other groups, resulting in a polyandrous system among siamangs

Answer 353

. In single male groups, if BGC increases, similar effect occurs, with a primary male tolerating other males, resulting in a polygynandrous system lowland western gorillas

Answer 354

several males stay with one female and provide paternal care to the offspring; males tolerate each other and the female will confuse paternity by mating with all the males.

Answer 355

penguins for thermoregulation

Answer 356

kin selection related individuals cooperate with each other the idea that an altruistic allele can improve its prevalence in the gene pool by promoting the success of the same allele in other individuals

Answer 357

Reciprocal altruism cooperation is maintained by reciprocity of exchanges (individuals cooperate only with those who also cooperate)

Answer 358

Group selection groups of cooperators outcompete groups of noncooperators.

Answer 359

Inclusive fitness = RSself + (RSothers * r) . Inclusive fitness includes the individual own fitness, plus the fitness of its relatives weighted by the degree of relatedness

Answer 360

if the costs of cooperation are low and the benefits are high, altruistic alleles can spread by mutually promoting their success. In this situation, individuals reciprocate altruistic acts, and this system enables long-term relationships.

Answer 361

true In baboons, most of social bonds are formed among family members, even if individuals can form friendships also with non-kin, but the rule is, among females, to associate and hang out with mothers, sisters and daughters In black-and white colobus, grooming and proximity relationships can be influenced by kinship

Answer 362

familiarity | phenotypic matching

Answer 363

mother-offspring siblings raised by same mother siblings and half-siblings? depends on mating system

Answer 364

When only one male is present, most likely all infants and juveniles are siblings and half-siblings. When multiple males live in the group, it is a bit more complicated to recognize beyond the matriline.

Answer 365

using physical similarities between individuals individuals need to use a referent, such as their mother or themselves (if they can recognize themselves). They would then use visual or olfactive clue.

Answer 366

Some studies show that chimpanzees can do it, other studies show that they can’t, some show that macaques fail while other studies show that they can use phenotypic matching

Answer 367

costs must be low and benefits must be high. a slow life history, for repeated interactions to happen, a relative stability of the group, to keep tracks of interactions, service-dependent behaviour, in the sense that one service can be reciprocated by another service, or by the same service.

Answer 368

grooming can be exchanged with food sharing food sharing probability is higher in bonobos when grooming has been exchanged among partners beforehand

Answer 369

no can also be traded for tolerance in tufted capuchins, of the tolerance among two individuals in two conditions: when they had no mutual grooming before, and they had groomed before. Individuals are more tolerant with each other after a session of reciprocal grooming furthermore, more grooming after being tolerant at food resources Tiddi et al., 2011

Answer 370

originally assumed to be no BUT in chimpanzees, some recent findings point in the direction of group-level benefits of cooperation. Chimpanzees carry on regular border patrols, mostly by males even if females can also participate, and patrols are typical collective and cooperative action with movement coordination and a common objective.

Answer 371

males who had more to gain because they have many offspring in the group participate more, which corresponds to an individual benefit. high ranking and physical strong males tend to participate more, also here suggesting an individual benefit. males who have no offspring or no relatives in the group also regularly participate, hereby suggesting a group interest or group benefit (though can also be seen as individual benefits, just cumulated); patrolling effort does not decrease with group size, as would be expected if only self-interested males would participate. This suggests again a group benefit and the absence of defection. T

Answer 372

male participation is maintained because the benefits issued from patrols, such as territory increase, allow group size to increase, conferring a larger competitive advantage to the group against other groups. Debated whether or not this corresponds to group selection of just to additive individual selection, given that the mathematics behind group and individual selection is the same.

Answer 373

Risks (costs): aggression Passive benefits: tolerance near resources Active benefits: exchange of commodities

Answer 374

Social relationships are structured around both risks of aggression and benefits of cooperation, and the balance between both is modulated by kinship, friendship and reciprocity

Answer 375

forming friendships removing parasites reducing stress

Answer 376

often bottom-up, following the hierarchy, | with subordinates giving more than receiving

Answer 377

by being exchanged against other favours such as tolerance, support during conflicts, protection and mating. Grooming is an easy behaviour to reciprocate, by mutual grooming.

Answer 378

eg in rhesus macaques, a very nepotistic species related individuals receive more grooming than non-related ones Call et al., 1996

Answer 379

the top 3 non-kin partners receive more grooming than top 3 kin partners, especially in high density. So here friendship matters more than kinship, especially at high density where tension between individuals is increased (given these are captive populations).

Answer 380

emotional score-keeping: nice interactions are remembered, and reciprocated oxytocin plays a major role in this emotional score-keeping and in promoting socialbonds

Answer 381

urinary oxytocin shows higher levels in bonded grooming partners, whether they are kin or not, than in non-bonded grooming partners oxytocin is higher among bonded partners than among non-bonded partners, and even higher than among kin partners in males. Crockford et al., 2013

Answer 382

yes | In chimpanzees, males form stable long-lasting and reciprocal bonds

Answer 383

Wild subordinate chimpanzees are more likely to sire if they have strong bonds with the alpha male Feldblum et al., 2021

Answer 384

passive form, which is more or less a form of food tolerance, and active food sharing, which is rare among animals and primates. Food sharing is assumed to reinforce social bonds

Answer 385

Adoptions happen in mammals, but these are rare events. In the Taï chimpanzees, where female mortality is high, due to predation and diseases, it is common to have young chimpanzees becoming orphans and being adopted by group members who look after them.

Answer 386

Yes Boesch et al., 2010 In Taï chimpanzees, 18 adoptions have been observed across 3 communities during 27 years of research. Half of the adoptions were made by an adult male, and only one was made by the biological father. In this population, the presence of kin in the group does not influence the probability of adoption Thus, adoption can be seen as a form of altruism, even if group benefits such as keeping a high number of individuals cannot be excluded. Individuals adopting provide substantial help to adoptees, such as food sharing and carrying them on their back

Answer 387

``` Gestation Birth Growth Reproduction Maturation Senescence Death ```

Answer 388

resources and energy are limited. These limitations due to resources get translated throughout evolution by evolutionary constraints, where natural selection cannot maximize fitness beyond certain limits

Answer 389

when an increase in one life history trait (improving fitness) is coupled to a decrease in another life history trait (reducing fitness), so that the fitness benefit through increasing trait 1 is balanced against a fitness cost through decreasing trait 2.

Answer 390

Life history strategies are inherited patterns of energy allocation to these basic functions at different points during the lifespan

Answer 391

reproduction, maintenance and growth

Answer 392

Maintenance mobilizes energy for repair of the body, vigilance, feeding, sleeping and the immune function. Growth mobilizes energy for the development of muscles, organs and the brain.

Answer 393

no they evolve and are dynamic they can changed based on: -extrinsic mortality changes (more or less predation, new diseases, …) -changes in food availability, distribution and abundance -changes in mate availability -changes in alloparent availability

Answer 394

Hyraxes. Hyraxes are small mammals that live in Arica, measuring between 20 and 70 cm and weighing not more than 5kg. Given their size, one would expect a relative short gestation period. However, hyraxes have a relative long gestation period of about 8 months. This trait, related to reproduction, is inherited from their ancestry. Ancestors of hyraxes were large mammals and hyraxes are the closest living relatives to elephants, who show a long gestation period predicted by their body mass.

Answer 395

fast growth, high reproduction output, short lifespan, rapid ageing and small size, are favoured in environments with high mortality risk, while this can evolve under natural selection, but physiology can also respond to cues during the life course through plasticity.

Answer 396

primates Primates have a longer lifespan as compared to other mammals (on an allometric scale, where primates are above the rest of the mammals for relative body weight). Primates have also small litter sizes (shown in another allometric scale, below other mammals relative to body weight). Charnov & Berrigan, 1993

Answer 397

2.3 years, with a maximum of 8 years in orang-utans

Answer 398

- Late maturation→ long juvenile period → long maternal investment - Slow reproduction - Single offspring (max. 2 Callitrichids) - Low adult mortality, long reproductive career - Long life span - Females live longer than males

Answer 399

where the mother nurses and provides milk during the first months of life, carries the infant, interacts with her infant, by playing and grooming, and she protects her offspring against other group members, against bad climatic conditions and against predators

Answer 400

direct, by carrying the twins, by grooming them and sharing food with them; indirect, in the form of protection and tolerance.

Answer 401

Callitrichids

Answer 402

Allo-parental care can be provided by other males (who could potentially be the fathers) as in multi-male groups were paternity is uncertain; by young females, by related individuals like older daughters, and in cases of adoption by a group member, related or not.

Answer 403

a long period of gestation, a relatively long period of lactation, and substantially some forms of food sharing trade offs between current and future offspring

Answer 404

offspring being bigger when the inter-birth interval is longer, meaning that delaying the next reproduction benefits the current offspring. The effect of a differential parental investment is persisting over the adolescence period, where bigger offspring remain bigger and smaller ones remain smaller as they grow.

Answer 405

. Shown by the relationship between creatinine, a marker of muscular mass, and age, between offspring that were looked after by their mother more than 5.5 years and those that were looked after for a shorter period of time those that were looked after for a short period of time remain smaller

Answer 406

Parental investment should be optimally allocated toward the sex that has the highest anticipated reproductive success (1973)

Answer 407

→ high-ranking females should favour sons → low-ranking females should favour daughters This differential should then be expressed and should appear in the sex-ratio at birth and in a differential investment after birth depending on the mother’s rank and on the sex of the offspring.

Answer 408

Given that male RS can be quite high, though variable, due to the winner-loser effect inherent of being a male as a primate, and given that females will always have some RS, the theory says that high-ranking females should invest into sons, and that low-ranking females should invest into daughters.

Answer 409

Boesch, 1997, found in wild chimps dominant females invest more into sons - IBIs are longer for dominant females who have a son, reflecting a longer investment in this current offspring, and inter-birth interval of subordinates is longer when they have a daughter as compared to subordinate mothers who have a son. In addition, when looking at survival curves of sons and daughters of dominant and subordinate mothers, we can see a clear effect of this longer investment in sons from dominant mothers, as their sons enjoy a better survival. In contrast, sons from subordinate mothers, who tend to resume reproduction fast, have the lowest survival probability less conclusive regarding sex ratio - Brown and Silk 2002: Meta-analysis 35 studies: No clear evidence for differential birth sex-ratio

Answer 410

in wild chimps: dominant females invest more into sons Longer IBI for dominant with a son Subordinate IBI longer if they have a daughter Sons of dominant mothers survive better (Trivers-Willard Hypothesis (1973))

Answer 411

Perret, 2018, investigated the paternal effect on maternal physiology. In mouse lemurs, t high testosterone levels in dominant males were correlated with more produced male-biased litters, suggesting a paternal effect rather than a maternal one. However, overall, differentiated investment at birth, resulting in differing birth sex-ratios, receives little support across primates

Answer 412

investment may be linked to philopatry rather than direct fitness depending on the sex

Answer 413

Male chimpanzees are philopatric, so it seems to pay to invest into sons when high-ranking, because sons will then have more chance to reach a high status in their own group. Also, in female philopatric species, it would pay to invest into daughters when highranked, due to the rank inheritance that daughters benefit off. Also, in female philopatric species, it would pay to invest into sons when low-ranked, since males may then gain a higher potential RS, especially because their mother’s rank is not passed to these males.

Answer 414

For the mother, it pays to wean her infant earlier so that she can invest into the next reproduction. From the infant perspective, it pays to keep suckling to get more free energy without having to invest into solitary foraging. Conflict occurs after the the more is ready to wean but before the offspring is ready to wean

Answer 415

For example, mother-offspring conflict can be seen by looking at the number of contacts between them: during this period of conflict, the mother breaks the contacts with her infant more often than the infant does, while the infant constantly searches for more contacts.

Answer 416

Weaned individuals (not infants, stopped suckling) Travel and feed independently Pre-pubertal (not yet reproductive)

Answer 417

Males physically grow faster than females males play socially earlier than females do female social development, in particular grooming, gets developed faster than for males Males tend to play more toward objects while females tend more to play a type of play called play-parenting juvenile capuchins tend to follow the foraging habits of the same-sex adults, females overlapping in foraging habits with their mothers, while juvenile males will overlap with what adult males feed on. In apes, where tool use has been extensively studied, some sex-differences occur

Answer 418

due to differences in the development of the motor control can be witnessed by looking at the first time they travel independently

Answer 419

In wild chimpanzees, independent traveling increases over time for both males, in black, and females but independent traveling increases faster in males than in females. (Lonsdorf, 2014) in blue monkeys, males decrease faster the contacts with the mother than females do

Answer 420

in chimpanzees, young males increase their rates of social play during infancy faster and earlier than do females. (Lonsdorf, 2014) in Japanese macaques, social play increases with age in both sexes but males tend to display more social paly than females. (Eaton et al., 1986)

Answer 421

in Japanese macaques, of the percentage of observation time where females and males were seen engaging into social grooming, as function of their age: already during the infancy females groom more than do males, mostly toward their mother This difference persists over time, during the juvenile period, with juvenile females who groom more often their mothers than do little sons. Eaton et al., 1985

Answer 422

Males tend to play more toward objects, as seen in wild chimpanzees, while females tend more to play a type of play called play-parenting in chimpanzees, some juvenile females have been observed playing with a stick and carrying the stick as they would carry an infant. In many other primates, play of young females directed toward other infants, such as interacting, carrying and playing with a baby have been observed, like in Western lowland gorillas, rhesus macaques, bonnet macaques and blue monkeys. These sexdifferences in play-orientation are thought to be predispositions for mating competition and parental investment, strategies that differ between males and females.

Answer 423

In chimpanzee termite fishing, females are more attentive to their mother’s techniques than males are, which results in a shorter acquisition time, and so in a greater proficiency for females than for males Lonsdorf (2005) found the time spent fishing termites is much higher and grows faster over age in females than in males, and that the percentage of time spent watching the mother fishing termites is much higher in females than in males, especially at a young age. HOWEVER, in chimps: In other types of tool use, however, such as ant dipping, no sex difference appears. in nut cracking behaviour, not sex difference has been observed throughout the ontogeny of this behaviour,

Answer 424

in ant dipping, no sex difference appears, probably because eating on ants is a risky foraging technique (due the bites of ants) that needs time to acquire. nut cracking: probably because getting skilled in nut cracking takes a lot of time, erasing potential difference that may exist in term of attentiveness or interest in learning the technique.

Answer 425

juvenile growth is slow, and juveniles can’t reproduce 3 hypotheses: ecological risk aversion hypothesis brain energy hypothesis needing to learn hypothesis

Answer 426

individuals stay small for a while to buffer high morality risks, high mortality risk due to high predation on small bodies and least efficiency in feeding. So, since juveniles are poor feeders, it would not pay to have them growing to full size too fast, they need time to acquire good skills to forage efficiently

Answer 427

large brains need a lot of energy, so the cost of brain development constrains energy available for body growth. In other words, large brains slow down development. Here again we have this idea of trade-off: the energy needed for brain development cannot be allocated to body mass.

Answer 428

it takes and needs time to develop full socio-ecological skills, such as foraging skills but also social skills like learning the hierarchy and other social attributes

Answer 429

Slow development and delayed reproduction have to be compensated by longer reproductive lifespan → What keeps adult mortality low? Only viable if adult mortality is low (otherwise risk of dying before reproduction)

Answer 430

large brains | arboreal primates and arboreal mammals live longer

Answer 431

primates that have larger brains live longer large brains allow reducing risk of mortality, being more clever help to survive large brains allow a better diet, better predation avoidance, and enable cooperative skills Allman et al., 1993

Answer 432

very strong | can be seen across all primate species or across diet, with leaf eaters and fruit eaters; and across social systems

Answer 433

a slower life history pace allows directly the possibility to develop large brains. These large brains in turn incur some fitness costs, such as adjusting to a slow development and a slow reproduction, but it guarantees fitness benefits, such as higher adult survival, traits that in turn comforts and maintains a slow life history.

Answer 434

easily escape to large predators, which are mostly terrestrial. individuals living in trees are less exposed to diseases

Answer 435

Shattuck & Williams, 2010 constructed an allometric scale of lifespan as function of body mass, for all mammals - the line of arboreal is above the line of terrestrial, showing a higher lifespan for those who live in trees.

Answer 436

Greater dependence on flexible learned behaviour Long parent-offspring association Larger social groups Association of females with males → Stable groups, long-term relationships, cooperation → Overlapping generations: social learning, culture

Answer 437

social learning opportunities and ability to have the time to develop a large brain

Answer 438

individuals can form long-lasting relationships and need each other to learn and survive

Answer 439

mostly due to sexual coercion by males who, due to the fact they have time, can be coercive with females and push them to stay with them permanently

Primate Behavioural Ecology Flashcards

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