Linking genes, environment and behaviour Flashcards

Question

Chimpanzee TOOL-USE & TOOL-MAKING (AT GOMBE & MAHALE)

Answer 1

* grass stems & twigs are modified to probe termite mounds * long leafy branches are used to sweep up ants from nests * clusters of leaves are used as sponges to obtain water from tree holes & to wipe sticky substances from the hair

Answer 2

Sticks up to 13 cm long are used to: * probe for wood-boring bees, insects under the bark of fallen trees, driver ants & honey * inspect each other’s wounds * investigate dead animals Logs or stones are used to crack: * two species of large, hard-shelled nuts (Panda & Coula) * placing other logs or stones underneath as anvils

Answer 3

* Bonobo * Pygmy or gracile chimpanzee * Restricted to south of Congo River * The second species of chimpanzee, genetically close to other species of chimpanzee (Pan troglodytes) * very different in behaviour!

Answer 4

BONOBOS: * Squat when resting * Calls are more shrill, almost birdlike * Temperament is livelier & ‘nervous’, their movements quicker * Red lips * MUCH LESS AGGRESSIVE * Female genitalia never quite detumesce & copulate throughout the sexual cycle (for pleasure) * show female homosexual behaviour (G-G rubbing) ANATOMICALLY, BODY PROPORTIONS MORE LIKE HUMANS: * smaller, rounder heads (skulls) * longer rear legs * stand more upright (often) * difference in weight between males & females more humanoid, females average 85% of male weight (in chimps they average <75%)

Answer 5

Feeding ≈ 40%; Resting ≈ 32%; Travel ≈ 16% & Interacting with others (mainly grooming) ≈ 6% DAILY RANGE mean 2 km

Answer 6

* Communitiy sizes at Wamba in 1980s, about 70-120 * Home range size 58 km2 * Home ranges of different communities overlap very widely

Answer 7

FEMALES DISPERSE: sometimes changing groups again after short periods * Overall sex ratio 1:1 * more adolescent females than males, * probably because dispersing females only enter new communities for short periods All males seem to stay in their natal community

Answer 8

PARTY SIZE AVERAGES 16.9 (usually 6 - 35) * At Lukuru mean 6.4 (1-22); * At Lomako mean 4.9 (1-16) Membership of a party usually stable for 2-3 weeks or longer (unlike chimpanzees) 96% OF PARTIES CONTAIN ALL AGES & SEXES * unlike chimpanzees * At Lomako, bisexual parties were only about 70% Proportion of oestrous females in a party can be as high as 98% Occasional all-male parties (last only 1-2 days)

Answer 9

At Lukuru (southerly site, with dry forest & grassland): * primary forest: 38% * secondary forest: 56.2% * grassland: 4.1% * riparian forest: 1.7% * they wade waste-deep into water to gather algae & sub-aquatic vegetation

Answer 10

Mostly Fruit (pulp & seeds), shoots, leaves, flowers, bark, stems, pith, roots, mushrooms, small mammals, grubs, earthworms, honey, eggs, soil * At Lomako: eat snakes, adult insects & blue duikers * At Lukuru: eat a lot of THV (terrestrial herbaceous vegetation) Earthworms are a favourite but form a tiny proportion of diet: – bonobos dig for them with their hands

Answer 11

NIGHT NESTS mainly in bokumbo tree (Leonardoxa) * About 13m above ground (38% at 10 -15m) * At Yalosidi, 7% of nests on ground Less selectivity for DAY NESTS * About 20m above ground (5 - 25m common) CONSTRUCTION TIME: * night nests 222 seconds or nearly 4 mins (96-412 secs) * day nests 42 seconds or < 1 min (3-241 secs)

Answer 12

Male typically solicits: 73% of cases Female presents either: * dorsoventrally: female stands quadrupedally facing away from male * ventro-ventrally: female lies on back in front of male Copulation most frequent (70%) early morning, between 5.30-9 a.m. * frequent at feeding sites * female may exchange food for sex Genito-genital (GG) rubbing: * 2 females clasp v-v, rubbing clitoris tips together * Occurs during periods of heightened excitement * Creates ‘harmonious stability’ Juvenile males sexually precocious * join in during copulation, thrusting at adults’ genitalia * mount adult & adolescent females * Adult males may thrust at them Juvenile females hardly ever engage even in GG rubbing

Answer 13

Many males have: – torn ears, missing finger joints, scars – aggression much less frequent than in chimpanzees * Glaring, bluff charging, charging, chasing & leaping while waving arms over another’s head * Biting, hitting, kicking, slapping, grabbing, dragging, brushing aside, pinning down, shoving aside SUBMISSIVE GESTURES INCLUDE: – prostration, grimacing, flight, avoidance, extending the hands, touching the other’s body, shrieking * Most frequent at feeding sites * Charging display similar to chimpanzees & often involving branch-dragging * Often subdued by dominant male mounting the subordinate, but no intromission observed MALE BONOBOS FAR LESS AGGRESSIVE THAN MALE CHIMPANZEES

Answer 14

At feeding sites: * females often take precedence over all except highest-ranking males Group of females may form a coalition against a male: * males don’t form coalitions to attack a female Close associations between females at Lomako are 6-7 x as common as those between males Neighbouring communities may avoid one another, or there may be mild aggression but: * NO COMMUNAL WARFARE has been observed

Answer 15

IN BONOBOS, FEMALE CHOICE IS CRUCIAL IN MATING * groups more cohesive than chimpanzee groups, e.g. party size often 25-30% of total community size, but usually <20% in chimpanzees * Social use of sexual behaviours increases females’ social status, & so reduces the reproductive value of copulation (Furuichi & Hashimoto, 2002) PARTY SIZE & COHESIVENESS MAY RELATE TO: * constant presence of ‘superabundant food patches’ (White & Wrangham, 1988) * or overlap in community ranges, & need for protection (Hohmann & Fruth, 2002)

Answer 16

Eastern gorillas: Mountain gorillas - 1000 Grauer gorillas - 3800 Western gorillas: Western lowland gorillas - 125000 and only subspecies found in zoos Cross river gorillas - 300 and

Answer 17

50-70% feeding 10% travelling 15-35% resting

Answer 18

Menarche: 7-7.5 years First birth: ≈ 10-11 years in wild Life expectancy: at sexual maturity can live on average another 17-19 years

Answer 19

Mating: ≈ 15 years (wild), 6-10 years (captivity) Becomes silverback: at 12-13 years Life expectancy: after becoming a silverback, lives on average another 10 years

Answer 20

Most gorilla populations live: altitude: from sea level - 1000 m forest types: lowland rainforest & swamp forest, especially secondary forest; bais (waterlogged clearings in rainforest); avoid monodominant areas (single plant species) In mountains west of Central African Lakes, Grauer’s gorillas live: altitude: up to 2500 m forest types: montane rainforest (including bamboo) Mountain gorillas live: altitude: at 3000 - 3500 m in Virunga Volcanoes forest types: montane forest (including bamboo), Hagenia forest, giant heath & Afro-alpine zones

Answer 21

Basic dietary staple is Terrestrial Herbaceous Vegetation (THV) Virungas: THV only: leaves, herbs, stems, pith, roots, bulbs, lichen, bark Intermediate mountain zones: more fruit eaten (10-20% in Kahuzi & Bwindi) Lowland forest: much fruit eaten (40- 63% in West African regions) – Gorillas prefer fruit & range widely in search of it – in Sangha valley region, gorillas enter bais & forage for aquatic vegetation, which has high mineral content (Na, Ca, K)

Answer 22

EASTERN GORILLAS: no seasonal difference WESTERN GORILLAS: * fruiting seasons: groups travel far in search of fruit * non-fruiting seasons: groups restrict their ranges & feed on THV – Lopé, Gabon (mixed forest): in fruiting seasons ≈ 1266m; in non-fruiting seasons ≈ 749m – Bai Hokou, CAR: reduces from 3100m to 2110m – Mondika, CAR (swamp forest): reduces from 1648m to 1118m

Answer 23

On the ground typical in many places Percentage of tree nests is higher in Grauer’s gorillas than in other gorillas In a multi-male troop: each silverback & his mates nest close together

Answer 24

VIRUNGAS: 1970s & 80s, most groups 1 silverback; 1990s, 28-40% had >1 silverback – females usually disperse, often several times – rank order reflects order in which they became dominant silverback’s mate – a few all-male groups recorded KAHUZI BIEGA: 8% of groups are multi-male (silverbacks) WEST AFRICA: most groups have 1 silverback – Maya Maya 0%; Mbeli Bai 8% – No all-male groups recorded

Answer 25

Silverbacks of 2 groups (or solitary male & group male): * Auditory display- communicate by hoot-series followed by chest-beats If groups are close, chest-beats are replaced by: * Auditory & visual display- ground-thump or branch-breaking or * Visual display only- vegetation tearing & sideways run

Answer 26

Chimpanzees & orangutans use natural objects as tools in wild, & sometimes modify them (i.e. make tools). IN 2005: 2 different adult female gorillas were observed to use tools use at Mbeli Bai, Congo (Breuer, Ndoundou-Hockemba & Fishlock, 2005). Efi & Fulani (her infant): stand at the edge of a clearing. Efi detaches a stem with both hands, pushes it into the ground, and uses it to stabilize herself while she pulls aquatic plants towards her with her other hand

Answer 27

Male reaching maturity (becoming a silverback): chooses to stay or emigrate If he stays (64%): he mates with unrelated females who join the group or are already in it (in Virunga, potential mates include half-sisters) If he emigrates (36%): he becomes solitary & begins to follow groups seeking females Female reaching maturity: usually (72%) emigrate & join another group that has approached All adult males (solitary & group males) try to gain females from other groups: * usually invade another group & ‘persuade’ females to transfer – younger males display at invader – dominant male tries to keep females & young in background – a very bloody fight between silverbacks may occur – there may be infanticide Solitary silverback who gains 1 female: will try to gain others if he cannot attract other females, the first soon leaves him Strong silverback keeps all his females: & may eventually lead a group of over 30 gorillas

Answer 28

In Virunga, infanticide accounts for at least 37% of infant mortality: * occurs most frequently after death of silverback in a one male unit, but also during inter-group encounters * Infants in one male units more likely to die from infanticide than those in groups with multiple silverbacks * not recorded, even in equivalent circumstances, in Western or Grauer’s gorillas

Answer 29

* Females solicit males unless another male is trying to compete * Have been observed mating ‘face-to-face’ * Females develop small, white labial swelling for 2-3 days around ovulation & mating is restricted to this time * During pregnancy, all females mate: – generally with other males (not prevented by mate) – or mount other females

Answer 30

Gestation: 257 days Cycle length: – 32-33 days (Western & Grauer’s gorillas) – 28 days (Mountain gorillas) Age at weaning: 3-4 years Inter-birth interval: – 47-51 months (if infant survived) – 12-26 months (if infant died)

Answer 31

* gorillas more ‘patchy’ distribution * chimpanzees more even distribution * gorillas build up much higher population densities

Answer 32

Bonobos yawn when they see a stranger yawn and exhibit altruistic behaviour. They also laugh.

Answer 33

Adult arrested males rape females Gorillas mostly peaceful but some males commit infanticide when they replace a rival male Male chimpanzees bash females to assert dominance Bonobo are ranked in pairs (male and female equally) much less violent. Sex is used to resolve conflict and community encounters are peaceful and relaxed.

Linking genes, environment and behaviour Flashcards

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