Primates Pt.2 Flashcards
(33 cards)
Anatomical traits and
behaviour linked
– e.g. male-male competition &
sexual dimorphism in body size
and canine size
Behaviour is a product of
natural selection on ancestral
populations resulting in
increased adaptation to
particular habitat
Socioecology
Socioecology: the approach
that explains variation in the
social systems of animals with
reference to ecological and
biological factors
Availability and distribution of
resources affects what
Availability and distribution of
resources → – competition – grouping – social behaviour – mating patterns
Social behaviour is a suite of
adaptations to the ecological
and social environment
what is needed for For survival and fitness?
– Find food
– Find and co-ordinate with mate
– Have offspring & rear offspring
– Avoid parasites & diseases
– Avoid predators
Costs of group living
(sociality)
– increased competition for
resources (food, mates)
– increased likelihood of
disease and parasite
transmission
– increased conspicuousness
(predation)
Benefits of group living
(sociality
– defense of territory/food
resources & mates from
competitors
– lower risk of predation
Benefits of sociality: Lower risk of predation
- Detection
- more eyes to detect predators
- Deterrence
- more individuals to mob or chase
predators away - Dilution
- smaller chance that any one individual
is the prey of the day when group is
larger-
Optimal group size
- The size and
composition of groups
reflects a compromise
between the costs and
benefits of sociality
for individuals
– magnitude of these
costs and benefits is
influenced by social
and ecological factors
Males vs. females (4)
Females compete over food
Males compete over females
Reproductive success limited by:
Females:
Access to resources
Males:
Access to females
Ecological pressures influence the distribution of females, and
males distribute themselves to maximize their access to females
High metabolic costs associated with
gestation and lactation
Food
- Supplies energy
requirements for survival,
growth & reproduction - Dietary specializations
drive numerous
specializations
– body size
– teeth form and number
– gut length
– hand (shape, function)
– locomotor and suspensory
systems
– brain size - Different kinds of foods in
different kinds of habitats
are distributed differently
in space and time
Diet correlated with body size in primates
Insectivores are
smaller than
frugivores &
frugivores are smaller
than folivores
Differences in size are
related to differences
in energy
requirements
Adaptations in the digestive tract
Primates unable to
digest cellulose →
microorganism for
cellulose digestion
Colobines: complex
multi-chambered
stomach with
cellulose-digesting
bacteria
Diet and brain size
‘Ecological intelligence hypothesis’
- Frugivorous primates
relatively larger brains than
folivorous - → Frugivorous primates
need larger brains to
remember location and
phenological status of fruit
trees
Distributions of resources and defensibility: Clumped distribution
→ May be defended
→ Territoriality
Distributions of resources and defensibility: Even distribution
→ Difficult to defend
→ Home ranges without defence
Resource competition: Cost of forming (large) groups
Negative effects on
energy
budgets
development
reproductive
performance
Resources determine type of competition * Scramble (‘first come first serve’)
Food is evenly distributed
Amount of food available per
individual decreases with
increasing group size
Resources determine type of competition Contest
- Food is found in defensible
clumps
– Individuals compete
aggressively over access to
resources
Dispersal in primates: Baboon-macaque-guenon group* Male dispersal is the norm
- Male dispersal is the norm
Dispersal in primates: Colobines, lemurs, apes, New World monkeys
- Female dispersal and
bisexual dispersal common
Why do animals disperse?
- Avoid inbreeding
– reason in many cases for
natal dispersal - Seeking better resources
- Result of intrasexual
competition
– but does not explain
species where individuals
leave voluntarily
