Compiled as a third-year student at the University of Edinburgh, based on the information given in lectures.
General points are shown in normal font; specific examples are given in italics.
- Some complex behaviours are
genetically based. Migratory
restlessness in warblers: high in Germany, low in Canary Islands where
they don't migrate, intermediate in hybrids (h²=0.45). Migratory response
can be altered by artificial selection.
- May be intra-sexual (fighting for mates) or inter-sexual
(showing off to mates).
- Elephant seals: males
are large and have bulbous noses. Females can't stop a male mating with
them but can 'protest' (which is more likely with unattractive males),
encouraging other males to intervene.
- Dunnocks: different mating
systems: monogamy, polyandry, polygyny, polygynandry. Chicks survive best in polyandrous
families where alpha and beta males both help feed chicks. % of feeds
given by beta male depends on his access to female (and chances of
paternity). Females try and surreptitiously mate with beta male to ensure
his co-operation. Alpha male guards female to prevent this, and pecks her cloaca before mating to force ejection of past sperm. Males'
and females' reproductive success depends on mating system - their interests
- Lions: a coalition of
brothers may take over a pride. It is advantageous for females to rear
young together, producing coalitions of brothers. Males taking over a
pride commit infanticide, which brings females into oestrus again.
- Observed in 7 mammal and 35 bird species (e.g. fallow deer, grouse, birds of paradise, humans).
- Success is skewed towards dominant males, though inferior ones
may get 'sneaky' matings.
- Reasons for lekking: males congregate at 'hotspots' where
females are likely to be? reduces risk of
predation? 'hotshot' males attract others? testing ground for good genes?
- Males may offer females resources (e.g. fly given as food by scorpion fly) or offer only genes.
- Long-tailed widow birds:
longer tails give mating success; can be demonstrated by manipulation.
- Sedge warblers: larger
song repertoires are attractive in males; can be demonstrated with taped
- Fisher's runaway selection: equilibrium is unstable.
- Covariance between male and female traits (in sticklebacks, son's intensity of red colouration is related to
daughter's preference for red males).
- Mate preference can be genetically determined (e.g. red/melanic preference in 2-spot
- Stalk-eyed flies: long
eye stalks attract females; artificial selection can shorten but not
lengthen stalks - has natural selection 'used up' the available variation?
- Sexy son hypothesis - do females behave like this because they want
- Not in pied
flycatchers: repeatability of mating success is low (maximum h² = 0.2) and
polygyny is rare.
- Handicap principle - males prove their worth with
characteristics that hamper their survival.
- Females benefit by choosing males with 'marker' if marker
doesn't reduce male's fitness below average fitness of unmarked
individuals. Selection can produce larger markers if fitter individuals
invest only part of their superiority in a larger handicap.
- 'Showiness' in birds may be related to susceptibility to blood
- Brighter male
bluebirds breed earlier, care better for young, and produce more
- Swallows with longer
tails return from Africa earlier, breed earlier, have more second broods,
have fewer 'fault bars' (signs of malnutrition) in feathers or broken
feathers. Experiments show that long tails hamper food-catching ability.
Parasite load affects tail length next season (demonstrated by moving
mites between nests). Mite resistance is genetic (demonstrated by moving
chicks between nests).
Mixed reproductive strategies
- Field crickets: loud
singing attracts both mates and parasites; 'satellite' males are silent
but get mates by hanging around loud males and intercepting visiting
scorpion flies steal flies from males by pretending to be females.
- Coho salmon: 3
year-old males develop big hook nose to attract females, but 2 year-old
males can remain as tiny 'jacks' forever - two possible life-history
strategies. Jacks more likely to survive to breeding age,
but have shorter breeding period and can't get so close to females.
Overall success rate of jack and hooknose strategies are similar, which
must be the case for the two strategies to persist.
- Tasmanian native hen:
females may share a territory with two males. If males are brothers, they should
co-operate if beta's gain in young is
more than twice alpha's gain. If males are
unrelated, alpha should evict beta.
- Inclusive fitness (IF) = 1 + rb - c (where
b is benefit, c is cost, and r is relatedness).
- Altruism will spread if 1 + rb - c
> 1 (in case of full siblings, where c < ½b).
- Altruism among unrelated individuals is not an Evolutionarily
- Siblings are selected to be altruistic when c < ½b and
selfish when c < 2b.
- Parent-offspring conflict - parents want siblings to co-operate
when c < b.
- Weaning conflict - parent wants to stop young suckling before
young want to stop - prolonged suckling reduces survival of future
- Reduction in mortality necessary to select for brood reduction
in nests is highest for siblicide, lower for infanticide, and lowest for suicide.
- Vampire bats: those
that fed well may regurgitate blood to feed those that didn't. Most common
among related individuals, but also occurs among unrelated ones that
associate regularly with one another (high 'association index'). Bats are
long-lived and have long-memories - they remember who has helped them.
Benefit to a near-starving bat is greater than the cost to a well-fed one.
Kin selection and co-operative breeding
- White fronted
bee-eaters: breed in 'teams' of related individuals.
- Grey-crowned babblers:
experimentally removing helpers from group reduces number of young
- Parents themselves make a lower contribution to feeding effort
in larger groups, helping parents' long-term survival and fecundity.
- Probability of helping depends on relatedness, but even
unrelated individuals may help if this help is reciprocated later.
- Next year's siblings will be full siblings (and more inclined
to help) only if both parents survive, so helping is most common in
- Florida scrub jays:
genetic gain of helper is 0.14, first-time breeder is 0.62. So why help?
- Other possible benefits of being a helper: gain experience,
inherit parental territory, gain a mate (unrelated helpers may usurp
breeders), group dispersal (as a coalition), reciprocal help.
- Pied kingfishers: on
Lave Naivisha, there is typically 1 helper, son of breeding pair. On Lake
Victoria, where conditions are harsher, there is a 2nd helper
who is unrelated and later takes over breeding female.
- Green wood hoopoes:
helpers form coalitions with younger siblings for group dispersal later.
- Breeder will want help, but helper will usually want to breed
alone if it has a good chance.
- Acorn woodpeckers:
store acorns in holes in tree trunks, requiring huge maintenance effort.
Higher proportion of young are retained as helpers when territory is
- Splendid fairy wrens:
shortage of females encourages birds to become helpers.
- Index of kin selection (Ik) = increase in young
produced as a result of helping
- Why do sons, not daughters, stay and help (in birds)? One sex
must disperse to avoid inbreeding. Males know they are related to siblings
but may be unsure about their offspring.
- Multiple pairs breeding in same nest.
- Groove-billed ani:
dominant female breeds last, having tossed out rivals' eggs.
- Benefits of communal breeding outweigh risks, but it is
worthwhile for dominant birds to 'pay' by allowing some of rivals' chicks
Seasonally-varying sex ratios
- In bivoltine species (2 generations per year), sons are more
valuable in first season because they can mate with females from second
season. In second season, daughters are preferred.
- Several adults together in a group; overlapping generations;
co-operation in nest-building, defence and brood care; reproductive
dominance, sterility or distinct castes.
- Sterile castes may work for their mothers (eusociality) or for
their sisters (semi-sociality).
Eusociality in Hymenoptera (bees, ants and wasps)
- Eusociality has evolved independently in several groups of
- Castes of ants:
worker, soldier, alate (winged reproductive animals), queen.
- Only females are workers, all males are reproductive.
- All Hymenoptera are haplodiploid - males are haploid (eggs
unfertilised), females are diploid.
- Workers' relatedness is 0.75 to sisters and 0.25 to brothers.
Females are workers because they are more interested in rearing sisters
(r=0.75) than their own offspring (r=0.5).
- Workers preferentially raise sisters, resulting in a
theoretical 1:3 male/female ratio, although queen lays male/female eggs in
a 1:1 ratio.
- Male/female ratio is indeed 1:3 in eusocial Hymenoptera, but in
solitary Hymenoptera and in slave-making ants (where workers are unrelated
to offspring) it is more like 1:1.
- At a 1:3 sex ratio, payoff for a worker is same as for a queen - so no bias
Eusociality in Isoptera (termites)
- Termites are diploid, and both sexes become workers.
- King and queen are highly homozygous (inbred), because
reproductives are produced not by founding king and queen but by their
offspring (brother-sister mating).
- Relatedness of offspring is 0.5, but relatedness of siblings is
nearly 1, favouring eusociality.
Eusociality in mammals
- Naked mole rat and
Damara mole rat colonies: reproductive, guarding, digging and foraging
- Colony is xenophobic and highly-inbred (mean r=0.81), favouring
- System has arisen in harsh environments where the colony
requires a large workforce.
- Some other mammals approach a eusocial state (e.g. badgers, where dominant female
exerts pheromonal control over the others to prevent them breeding).
Assumptions of foraging theories
- Decision assumptions - what do we think the animal is deciding?
- Currency assumptions - how does it evaluate the decision (e.g.
- Constraints - intrinsic (discrimination ability), extrinsic
(characteristics of the environment)
- Conventional constraints: exclusive search and exploitation
(can only do one thing at a time), sequential random encounters, complete
- Holling's disc equation: Pe
= (a' N T) / (1 + a' N Th) where Pe is number of prey eaten, a' is searching
efficiency (attack rate), N is prey density, T is total time, Th is handling time.
- Intake rate, Pe/T = (a' N)
/ (1 + a' N Th)
- At high prey densities, intake rate is inversely related to
handling time (Pe/T --> 1/Th).
- Holling Type 2 functional response is hyperbolic curve (e.g. in parasitoid wasps).
- High a' produces steeper curve than low a'. Damselfly nymphs: larger prey have
higher handling time, lower attack rate, shallower functional response curve.
- Type 1 functional response: linear increase in prey intake up
to a maximum.
- Daphnia filter-feeding
on yeast: Type 1 functional response due to simultaneous search and
- Type 3 functional response: sigmoid curve (sometimes seen in parasitoid wasps due to effect of probing time,
which increases with larger prey).
The prey model
- Energy intake rate, R = E / (s + h) where E is energy content
of item, and s + h are search and handling times.
- Prey item should be taken if it would improve average energy
intake: Ei/hi > mean E/(s+h)
- If food is easy to eat but hard to find, predator should be
indiscriminate. If food is abundant but hard to handle, only
high-profitability foods should be eaten.
- Poor environments (high s) should promote less specialised
diets than rich environments.
- Overall energy intake rate for a group of prey items: R = SpiliEi / (1 + Spilihi) where is l is encounter rate and p is probability of prey being attacked
- this is similar to the disc equation.
- Prey types should either always be taken or not (zero-one
- Prey types should be ranked by profitability (e/h) and added to
the diet in rank order, until profitability of next item is less than
weighted average profitability of previous items.
- Inclusion of an item in diet depends on its profitability but
not on its encounter rate.
- Crabs eating mussels: prey
choice not quite as expected - a few low-profitability items taken.
- Possible reasons for this violation of theory: discrimination
errors, long-term learning, prey parameter variation, runs of bad luck,
simultaneous encounters, averaging across individuals.
- Great tits eating
mealworms: encounter rates of different-sized prey manipulated
experimentally - results closely match prey model predictions, but still a
few inferior prey items were taken.
- Lions eating
herbivores: observed diet closely matches predictions of prey model.
Marginal value theorem
- Gain curve (residence time in a patch, ti,
against cumulative gain, G) can be plotted on a graph - optimum residence
time (maximum G/t) is point at which a tangent drawn from time 0 touches
the gain curve.
- If patches differ, the optimum strategy is to treat each as if
it were the 'average patch'.
- Travel time is positively related to time spent in patch (in great tits, paper wasps, starlings,
- Patch depression: intake rate declines as exploitation of a patch
- Possible patch use rules: leave after catching n prey, leave
after t seconds, leave after g seconds of unsuccessful search (this
'giving-up time' rule produces results that closely approach the optimal
solution), leave after instantaneous intake rate drops below a critical
- Amount of Food A eaten can be plotted
against amount of Food B eaten, and lines drawn representing limits (e.g.
minimum energy requirement, maximum foraging time).
- The energy maximising solution (e max) will be at
one corner of the feasible area; the time-minimising solution (t min)
will be at another.
- Moose, whose normal
diet is twigs, also eat pondweed because they need sodium. Like many
herbivores, they appear to be energy-maximisers, but there are doubts
about the validity of this conclusion.
Why animals live in groups
Finding food as a group
- Finding food: active recruitment (e.g. honeybees), cue in on successful foragers (local
enhancement - e.g. Japanese macaques), follow successful foragers from roost (e.g. common terns).
- Catching difficult prey (e.g.
hyenas hunt in larger groups for zebra than for wildebeest).
- Lions: when food is
scarce, solitary females do better than groups of 2-4, but groups of 5-6
- Harvesting renewing food - more efficient to do it as a group
than to randomly compete (e.g.
hummingbirds at a feeder, where competitive losses are balanced against
- Preventing interference by defending a territory.
- Costs of group feeding: prey disturbance (e.g. redshanks on seashore), problem of divisibility of food
source (house sparrows hog
indivisible bits of bread but share crumbs).
Avoiding predation as a group
- Vigilance - when predators rely on surprise, many pairs of eyes
are better than one.
- Redshanks threatened
by peregrines: individual scanning rates are lower when in a larger group.
- Why should animals do their fair share of scanning? Cheetahs chase less vigilant gazelles.
- Assumption of collective detection. If one sparrow flies off (when experimenter throws something at
it) the others don't usually follow, but if two sparrows leave at once the
whole flock takes flight.
- Response affected by distance to cover (the sparrows fly off more readily when far from cover).
- Edge effect - those on the edge of a group are more vulnerable
and can see better - they should be more vigilant. True in starlings, but not in redshanks (which are threatened by
- The Selfish Herd: cost (higher probability of attack) <
benefit (lower probability of capture)
- Confusion effect - difficult to pick out an individual in a
herd (explanation for zebra stripes).
- Alarm signalling - why draw attention to yourself? To protect
relatives, or get lost in chaos.
- Dilution effect - large groups overwhelm predators (e.g. Adélie penguins entering water).
- Encounter effect - decreased probability of detection by
predator when animals are together.
- In redshank groups
larger than 30, probability that at least one individual has its head up
decreases. They may be relying on dilution effect.
- Living in groups increases conspicuousness, but this cost tails
off with increasing size, so some animals may live in massive groups (e.g. monarch butterflies).
- Ostriches and cichlids
steal each others' young to create larger groups.
- Group sizes tend to be larger than optimal, because an
individual's alternative (going it alone) is worse.
Avoiding detection by predators
- Prey may avoid detection by: immobility, crypsis, confusion,
exploiting perceptual limitations.
- Apostatic (frequency-dependent) selection - most predators prey
preferentially on common prey types (e.g.
chicks fed green and brown pellets), due to formation of search images
etc, so rarity is advantageous. Some prey may appear rare through
polymorphism (e.g. snails).
- Probability of detection increases with viewing time - longer
for more cryptic prey.
- Guppies have smaller
and fewer spots when under high predation pressure.
- Crypsis depends on context. New
Zealand birds are drab because their predators can see in colour.
- Confusion: unpredictable movement, extreme abundance, flash
- Sensory and perceptual limits: minimum distance for pattern
element or colour, flicker fusion, private wavelengths, sealed shells to
prevent chemical leakage.
Avoiding attack by predators
- Avoid identification: masquerade as an inedible object,
confusion, aposematism (warning colouration), mimicry, honest signalling
of unprofitability (e.g. stotting in
- In Müllerian mimicry both species are unpalatable; in Batesian
mimicry the mimic is harmless.
- Mimicry is not just visual (e.g.
ultrasound in distasteful moths at risk from bats).
- Predator learns warning colouration more effectively at high
prey densities - strong stabilising selection, leading to monomorphism.
- How does distastefulness evolve? Prey surviving attack? Kin
selection? Synergistic selection?
- Predators learn a
conspicuous colour pattern quickest (chick-eating-pellet experiments again).
- Aposematic patterns should be simple, repeating and all-over.
Arms races and co-evolution
- In parasite-host systems there is very specific adaptation (e.g. cuckoos).
- True co-evolution is rarer in predator-prey relationships, but
there are some examples - night-flying
mantids, unlike most mantids, can hear bat echo-location frequencies.
- In general, groups of predators co-evolve with groups of prey: as more shell-breaking predator
families evolved, unshelled gastropods declined and gastropods with good
- Evolution tends to be faster in prey than in predators due to
life/dinner principle (the rabbit has more to lose than the fox!), larger
numbers of prey and shorter generation times.
Avoiding approach of a predator
- Mode of fleeing: outrun predator, sprint to cover, use
different style of motion (e.g. fly away).
- Behave unpredictably, or use startle, bluff or threatening
- Encourage premature attack (e.g.
Avoiding capture by a predator
- Avoiding subjugation: strength to escape, physical toughness (e.g. ticks), mucous or slime,
autonomy of body parts (e.g. lizard
tails, starfish arms), head hiding or false heads, spines or other
structures, adhesives (e.g. black
widow silk), jaws and claws, noxious tastes, poisons, stings, group
defence, resistance to venom (e.g.
California ground squirrels and rattlesnakes).
- Avoiding consumption: safe passage through gut (e.g. molluscs), emesis (triggering vomiting - e.g. Monarch butterflies), being
poisonous (may only benefit prey through kin selection!).
- It is in prey's interest to interrupt predation as early as
possible: at later stages, predator is increasingly close, more energy is
required to stop it, and predator is less willing to give up.
Life histories and reproductive decision-making
Trade-off between current and future reproduction
- Can be studied using brood-manipulation experiments.
- After artificial brood increases, 5 out of 14 studies found
decreased local survival of parents (mortality? emigration?); 8/14 found
decreased later fecundity (physiological impairment?).
- Effect of brood increase on parents is not compelling, but
increase in chick mortality resulting from increase in brood size is
Timing breeding to coincide with peak in food supply
- Variations in timing of breeding are retained in population as
a balanced polymorphism by year-to-year variations in timing of food
- Earliest breeders are typically most productive - average bird appears
to behave sub-optimally. This is explained by individual optimisation.
Trade-off between fewer superior young earlier and more inferior young
later - depends on quality of territory/individual.
Variations in parental risk-taking and investment
- Adults of longer-lived, less fecund species should be less
willing to put themselves at risk for their offspring. Nuthatches belonging to species with
higher fecundity/lower survival respond more strongly to egg predators;
other nuthatch species respond more strongly to adult predators.
- Males should invest more in their young if monogamous.
- In polygynous species, females in good condition should favour
sons. Feral horses in New Zealand:
females in good condition allow sons to suckle longer; mares in good
condition at conception give birth to more sons; those in poor condition
produce more daughters.
- Optimum investment in offspring during pregnancy is higher for
foetus than for mother.
- Pregnancy sickness in
humans: benefits foetus (by reducing exposure to toxins) but harms mother.
- Manipulation of mother by foetus - foetus secretes placental lactogen, which soaks up insulin so
blood glucose rises, mother responds by overproducing insulin - may lead
Role of behavioural ecology in conservation
- Small populations - are they at particular risk (through
reduced vigilance/group defence)?
- Sex ratio - might additional feeding (e.g. kakapo), or hunting, alter the ratio?
- Understanding mating system. Sperm whales: originally thought to have harem defence, so most
males were superfluous and it was OK to kill them. Now shown not to be the
case - a few older males move between groups of females while young males
remain at high latitudes.
- Predator-prey interactions - are ecotourists perceived as
- Exploitation (e.g.
Atlantic cod: at low densities, fish congregated in preferred areas,
- Reducing predation - killing off predators (e.g. introduced mammals in New Zealand) is often ineffective
and problematic. Habitat can be manipulated to reduce predation.
Deterrents can be used (e.g.
electrified dummies to reduce tiger predation on humans).
- Conservation practices may increase predation (e.g. removing rhino horns to deter
- In 'true communication', both sender and receiver benefit (on
average) from the exchange.
- The receiver's response to a signal affects the sender's
fitness as well as its own.
- Information exchange may occur without signalling (e.g. 'local
enhancement' at feeding sites).
- Communication may be interspecific (killdeer plover feigns broken wing to lead fox away from nest).
- 'Amplifiers' may assist in signalling (e.g. dark markings to highlight size of fish).
- Levels of analysis: causation, survival value (function),
evolution, ontogeny (development).
- Ways of analysing displays: motivational, interactional, economic.
- Different channels of communication (chemical, auditory,
visual, tactile) have different properties (range, rate of change, passage
round obstacles, locatability, energy cost).
- Model of signal evolution: sender associates incipient signal
and condition, receiver perceives signal against background, receiver
associates incipient signal with condition, receiver associates updated
information with decision, receiver responds. Feedback loop leads to
ritualisation and refinement of signal.
- Signals can jump from one system to another. Macaques: females present sexual
swellings on rear to males to show receptivity. Males use this presentation
posture to each other as sign of appeasement. In some species, male rear
mimics female rear to enhance this signal.
- Ambiguity - tits
displaying at territorial boundaries: a head-up display has an equal
probability of leading to approach/attack or to fleeing; head-down birds are
more likely to approach/attack.
- Receiver's actions can be important - pigeon guillemots give hunch-whistle displays when defending their
territories: if intruder responds by sitting, owner may sit too, but if
intruder walks, owner is likely to hunch-whistle again.
- Sender pre-adaptations: intention movements (e.g. sky pointing in gannets before
leaving nest), ambivalent behaviour (e.g. forward threat posture in black-headed gull), protective
responses (e.g. primate facial
expressions), autonomic responses (e.g.
urination leads to scent marking, heavy breathing to vocalisations),
displacement activities (bits of out-of-context behaviour - e.g. preening in duck courtship),
redirected attack (e.g.
grass-pulling in aggravated herring gulls).
- Receiver pre-adaptations: lizard
vision is attuned to jerky movement, leading to head-bobbing displays;
male water mites smell like food to attract females.
- Environmental selection pressures: eavesdropping by predators (e.g. snakes following mouse scent
trails), physical structure of environment, influence
of other signallers.
- Great tits alarm
calls: mobbing call (intended to be heard by predator) spans wide range of
frequencies; "seet" alarm call (not intended to be locatable by
predator) is a pure tone, at a frequency that great tits can hear better than sparrowhawks (predators) can. This creates
convergent evolution among passerine birds (different prey species have
similar alarm calls) and arms races between predators and prey.
- Social organisation is a dynamic phenomenon, and may vary
between populations of the same species (langur monkeys live in larger groups where habitat is richer).
- Social organisations reflect adaptive responses to selection
pressures acting on individuals.
- Females are the limiting sex; female distribution depends on
ecological factors. These influence distribution of females, size and
characteristics of female groups, and interactions with males (need for
paternal care, feasibility of mate guarding, etc). These in turn influence
distribution and behaviour of males. Social organisation arises from these
Describing social organisation
- Population structure (demography). Rhesus monkeys: in larger groups, average relatedness is lower and
infants keep closer to their mothers - group size influences maternal
behaviour. Large monkey groups are likely to fission (split) along
matrilineal kinship lines.
- Spacing behaviour: inter-society dispersion, or dispersion of
- Social system: behaviour within societies.
- Mating system: monogamy, polygamy, polygyny, etc.
- Changes with time. Red
deer become aggressive and territorial during rutting season. Tits and
chaffinches are territorial during breeding season but form flocks later
in the year.
- Home range: the area used by an animal during routine daily
- Home ranges may overlap extensively when costs of defence are
too great (e.g. in baboons).
- Territory: fixed area from which intruders are excluded by
advertisement, threat or attack.
- Solitary (e.g. bears, cats other than lions).
- Aggregations: animals are drawn to environmental resources
- Anonymous groups (e.g.
migrating herds of ungulates, flocks of birds).
- Societies: usually have restriction of membership (same
species), limited membership (same individuals), definite attraction
between individuals, contrast between inter- and intra-society
communication, division of labour, co-operation, synchronisation
- Four different species (or subspecies) of 'common baboon' (Papio) are widely-distributed in sub-Saharan
Africa; their societies differ from those of the 'sacred' Hamadryas
- Common baboons live in multi-male/multi-female groups (no
- Hamadryas baboons have a harem group structure: a troop
consists of an association of many 'clans', comprising harems and bachelor
- Common baboons will learn Hamadryas baboon ways if introduced
to a Hamadryas troop.
- Common baboons living on the savannah have large, overlapping
ranges; those living on forest edges (where food is more abundant) have
smaller ranges and are more territorial.
Social hierarchy in baboons and macaques
- Dominance: a consistent outcome of social interactions in
favour of the same dyad member, and a default yielding response of its
opponent rather than escalation.
- In primates, males usually outrank females. Male and female
ranks are drawn up separately.
- In common baboons: male ranks are less stable than female ranks
(due to movement of males between groups), male ranks are based on age, female ranks are based on matrilineal kinship.
- High rank doesn't necessarily equate to a high level of
- Supplanting: one baboon takes over another's food source. Corms
(swollen bulb-like stem bases) are harder to find than grass, but
supplanted more because they have higher nutritional value. Supplanted
baboon is less likely to resume feeding on same food type if it is corms.
Proportion of supplants involving grass (vs. corms) is higher when baboons
are close in rank - they take the opportunity to reinforce rank positions.
Baboons know each others' ranks.
- Basic rank: judged on the basis of dyadic interactions (between
- Dependent rank: depends on the behaviour of others (e.g.
relatives who intervene in fights).
- Dependent rank may become assimilated into basic rank.
- Females support relatives (altruistically) in fights; the risk
they are willing to incur depends on relatedness. Animals will intervene
readily in fights with low-ranking individuals (low risk), but only
intervene in fights with high-ranking individuals if a close relative is
- Protective threat position: juveniles may put themselves beside
an adult and threaten another juvenile, so any reciprocal threat also
annoys the adult.
- Sub-adult male may grab a baby and use it as an excuse to
approach an adult male - they can enhance their rank by associating with
- Rhesus macaques scream to recruit assistance in fights - type
of scream depends on who is attacking and whether or not there has been
- Facial expressions are also used - different expressions can be
given to different individuals.
- Higher ranking females have greater reproductive success (breeding
earlier in life, shorter inter-birth intervals, higher fecundity, lower infant mortality) due to better nutrition.
- Male rank is also correlated with reproductive success
(although this is hard to measure due to changes in rank and uncertainty
- Daughters inherit maternal rank.
- Principle of young ascendancy: younger siblings come to outrank
older ones due to preferential treatment by mother (younger siblings have
a higher future reproductive value).
- Among animals in captivity, dominance hierarchies may be badly
Practicals and self-teach work
The amorous Gammarus
- In freshwater shrimp Gammarus
pulex, male guards female for several days prior to copulation.
- Number of eggs produced by female is correlated with body size.
- 'Giving up time' is time taken to separate when pre-copula
pairs are taken out of water.
- Body lengths are normally distributed; cube roots of giving-up
times are normally distributed.
- Male and female sizes within mating pairs are strongly
- Male and female sizes are correlated with giving-up times, but not
- Both males and females prefer larger mates.
Sexual dimorphism in primates
- Sexual dimorphism (male/female mass) is significantly
correlated with male competition.
- Arboreal/terrestrial species are more sexually dimorphic than
purely arboreal species.
- Frugivores are more sexually dimorphic than folivores or frugivore/insectivores.
Feeding behaviour in locusts
- Bite mass is larger on cabbage than on barley or grass.
- Food intake rate (bite mass × frequency) is higher on cabbage
and grass than barley.
- Cabbage was the preferred food (measured by time spent and food
Foraging behaviour - the disc equation
- 'Forager' has Type 2 functional response (hyperbolic curve) due
to finite handling time.
Methods of recording behaviour
- Sampling rules: ad libitum, focal (monitor particular
individuals), scan (do a rapid census).
- Recording rules: continuous (record frequency or duration of
events), time sampling (record behaviour at specific times), one-zero
(record whether an event happened during time period).
Levels of measurement
- Nominal: classification into labelled categories with no
natural order (e.g. male/female).
- Ordinal: ordered but differences between values are not
important (e.g. rankings).
- Interval: ordered, constant scale but no natural zero (e.g.
temperature in °C).
- Ratio: ordered, constant scale with natural zero (e.g. age,
Analysing differences in dependent variables measured on a
- With independent samples measured under two conditions, use
'unrelated' 2-sample t-test (parametric) or Mann-Whitney U-test
- With paired samples measured under two conditions, use
'matched' paired-sample t-test (parametric) or Wilcoxon matched pairs test
- With independent samples measured under three or more
conditions, use one-way Analysis of Variance - ANOVA (parametric) or
Kruskal-Wallis test (non-parametric).
- With paired samples measured under three or more conditions,
use repeated measures one-way ANOVA (parametric) or Friedman test (non-parametric).
- Use two-way ANOVA if there is more than one independent
- If x and y values are both measured, and neither is imposed by
experimenter, use Pearson correlation (parametric) or Spearman rank order
- Use regression analysis (parametric) if x
values are imposed and y values are measured.
Analysing differences in dependent variables measured on a
- Use chi-square goodness of fit test or G-test to measure
goodness-of-fit between observed and predicted values.
- Use chi-square contingency test or G-test contingency test to
test for association between two factors.
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