THEME 1

Question 1

What does behavioural ecology aim to assess?

Answer 1

the effects of evolutionary and environmental factors on animal behaviour

Question 2

What is behavioural ecology?

Answer 2

1) The influence of Natural Selection on behaviour.
2) An animals struggles to survive and reproduce by exploiting and competing for resources, avoiding predators, selecting mates and caring for offspring
3) how animal societies reflect both cooperation and conflict among individuals

Question 3

What are Tinbergen’s 4 whys?

Answer 3

1) Ontogeny (development) - developmental explanations for changes in individuals (e.g. cognition and imprinting)
2) Ultimate (evolutionary) Why a species evolved the adaptions it has
3) Mechanism (causation) - mechanistic explanations for an organisms’ behaviour (hormones, nerves, genes)
4) Phylogeny (evolution) - the history of the evolution of behavioural changes in a species over many generations (e.g. parental care)

Question 4

Give an examples of Tinbergen’s 4 whys in starlings

Answer 4

Development
Learnt from parents and neighbours

Ultimate
To attract mates for breeding

Causation
Internal and external factors: increasing day length triggers changes in hormonal levels in the body, or the way air flows through the syrinx and sets up membrane vibrations

evolutionary history
Song evolution – simple sounds in primitive birds, complex songs in starlings evolved

Question 5

Why do female goats have horns?

Answer 5

• Unwanted advances from males
• Protect and kid and food from other females
• Protection from wind animals in the open (forest bovid don’t seem to have them)

Question 6

Give 3 ways proximity loggers record behaviour and physiology

Answer 6

Proximity loggers

• Broadcast unique ID & ‘listen’ for other Ids
• Frequency and duration of ‘contacts’ logged
• Data download at recapture

Question 7

Is there evidence for individual selection?

Answer 7

Individual magpies lay the clutch size that produces most you for them: a function of territory quality. Adapting to resources available

Question 8

How do phenotype and genotype both get effected by natural selection, and how do they relate to one another in terms of passing fitness onto future generations?

Answer 8

It is the phenotypes of individuals that, by interacting with the environment, are subject to natural selection (selection pressures)

But a phenotype lasts one generation; it is not inherited.

It is the individual genes (and not an organism’s whole genome) responsible for particular aspects of the phenotype being passed into the next generations with varying frequency, depending on the result of natural selection

Dawkins:
Individuals are vehicles; genes are replicators

Question 9

What did Tinbergen study?

Answer 9

Tinbergen is credited with being one of the founders of the field of behavioural ecology

Examines the adaptive significance of behaviour, or how behaviour may increase survival and reproduction.

Question 10

Give the modern version of Tinbergen’s questions

Answer 10

Motivation – Proximate/immediate causation

Development – in the individual

Function – What problem does it solve?

Evolution – Ultimate causation

Question 11

Describe how the ground finch on Daphne Major island, show the evolution of behaviour and natural selection?

Answer 11

E.g. Daphne Major island – Galapagos – medium ground finch
Variable beak sizes
Small bills are better at small seeds and big is big seeds
But in 1985 there was a drought – only small seeds were produced
Therefore natural selection for small billed birds
What was found that in just one year there was a sudden change in the populations average beak size

Question 12

Describe how speciation could occur in finches on Daphne Island

Answer 12

New finch that was bigger and different song ‘named big bird’ suggested come from other island

Hybrid, could potentially mate with the resident birds but didn’t – females weren’t selecting them because not the right song

Question 13

How do you measure/investigate the fitness consequences of a behaviour? And how do you measure/investigate the ‘function’ of a behaviour?

Answer 13

Behavioural ecologists seldom do this directly – interns of long term fitness – usually investigate at a functional level. You measure the function of behaviour by:

• Comparative studies
• Experimental manipulation
• Modelling

Question 14

What is Optimization prediction

Answer 14

behaviour maximises fitness

e.g. Gazelle will visit waterhole x times per day

Question 15

What is the Optimization criterion

Answer 15

maximum net benefit = max(b-c)

Question 16

Give the benefits and costs of foraging

Answer 16

Foraging (= searching + handling food)

Benefit = energy intake
Cost = energy used in finding & handling food items

Question 17

What are allocation costs and opportunity costs?

Answer 17

allocation costs = energy/time (usable for other things)

opportunity costs = cost of not performing other behaviours

Question 18

What are Darwin’s 5 points?

Answer 18

Variation: Individuals within a species differ in their morphology, physiology and behaviour

Heritable: some of this variation is heritable and on average, offspring resemble their parents more than other individuals in the population

Competition: number of offspring produced and number of individuals with successful breeding doesn’t match; population number tends to stay the same – due to competition

Adaption: as a result of competition only the fittest breed – best at gaining resources. This ability is passed on, and through NS over generations adaptions occur

Evolutionary change: in the environment changes then other variants would do best, and therefore NS occurs

Question 19

If natural selection only works genetically how do behaviours evolve? What considerations should you keep in mind?

Answer 19

• Might still be or have been behavioural alternative
• Differences must be of have been heritable
• Some must have given greater reproductive success than others

Considerations:

• The link between molecular genetics and behaviours is complicated
• The link works both ways, behaviour can effect gene expression
• Genes can be shown to influence behaviour, but might not produce it

Question 20

Give an example of how the same gene can give 2 different responses in 2 different animals

Answer 20

Drosophila vs. Honey Bees

Drosophila:
2 morphs – sitters and rovers

forR: go foraging much further for food and can take advantage of other food patches, thrive on patchy food and high larval density

forS: sit in the same patch, thrive on evenly spaced uniform food resource

Different alleles of one gene determines this. The percentages: 30% S, 70% R, found in Toronto. Morphs are maintained due to competition being highest within morphs
I.e. a sitter does best surrounded by rovers and the other way around

Bees:
The same ‘for’ gene dictates change in job in worker honeybees
Swapping from sorting honey inside the hive (sitting) or finding nectar (roving)

Question 21

What did V.C Wynne-Edwards suggest about grouping of species?

Answer 21

If a population over exploited a resource they’d go extinct, so adaptions have come about to ensure the group or species controls it rate of consumption

That they control their breeding rate to prevent over population; producing less young or delaying breeding

Question 22

Describe the example experiment on Great Tits in Oxford that proves is V.C Wynne Edwards wrong

Answer 22

Nest in boxes and lay 1 clutch ion the spring
Adults and young all ringed
Eggs of each breeding pair are counted (most 8-9 a year)
Young are weighed and their survival is recorded

Results
Incubation ability isn’t the factor, as adding eggs they can still look after them
Once hatched it is the feeding that is the problem
Over a certain size they can’t do it well
Chicks will get less food less often and be smaller when they leave the nest, lighter chicks don’t survive as well
Through experiments there was an optimum number of eggs found to maximize young survival (from a selfish individuals point of view)

Question 23

The most commonly seen clutch size in birds is seen close to the optimum, but slightly lower…. Why? Give 2 hypotheses

Answer 23

1. If brood size effects adult survival it is expected that the brood size that would give the adult greatest reproductive output would be lower than the largest one they could produce for just that season
2. Great tits if given more eggs can rear them, but we have ignored the egg production and incubation energy. A fairer test would to be somehow manipulate the birds into laying more eggs, rather than giving eggs

Both hypotheses involve measure trade-offs:
• Adult reproduction and adult survival trade off
• Trade-off between investment in egg production and incubation vs. chick care

Question 24

What is phenotypic plasticity?

Answer 24

The ability of a single genotype to alter its phenotype in response to environmental conditions (adaptability)

Question 25

Give an example of phenotypic plasticity in great tits

Answer 25

Songbirds breeding earlier because of climate change

• UK great tits – plastic – Have altered their breeding time since the 1970s by about 2 weeks due to caterpillar emergence
• Netherlands great tits – experienced similar to UK birds, but no change seen. Causes reproductive unsuccessfulness. (Plasticity is heritable so NS should be occurring here)

Question 26

Why do hole nesting birds and ground nesting birds have different behaviours

Answer 26

Hole nesters vs. ground nesters

Have different behaviours all due to reproductive nest location:

Ground nesters:
Camouflaged eggs, warning predator calls, once hatched chicks hide in vegetation, mother chick calls

Hole nesters
No need for all of the above. Hole nesters have larger clutches because

Question 27

Why do male lions do infanticide when they take over a pride?

Answer 27

Males kill cubs after take over = Infanticide

Killing cubs brings the females back into repro, therefore:

• Can produce his own offspring faster
• Males repro lifetime is short, so a male that practices infanticide gets more cubs, therefore this trait is passed on more than the trait of not using infanticide

Question 28

Describe the components of a lion pride

Answer 28

Lions pride consist of 3-12 adult females, 1-6 adult males and several cubs

All females stay to breed and stay with pride, but young males leave around the age of 3, and after a few years try and take a new pride from a weaker male.

Question 29

Female lions in a pride are in sync with each others reproductive cycle so they all breed at once, why?

Answer 29

Female lions are in sync, which is advantageous because:

• cubs born together survive better due to communal suckling,
• males will have similar ages companions to leave the pride with and therefore more likely to take over a new pride successfully

Question 30

What are the 3 ways to test behaviour?

Answer 30

1. Comparisons between individuals in a species: success may vary between individuals
2. Experiments – can vary one factor at a time,
3. Comparison amongst species – different pressures and needs give information onto why different things effect different animals

Question 31

Give 4 downfalls to the comparative method

Answer 31

1. Alternative hypotheses
   The explanations given are certainly plausible but other hypotheses haven’t been rigorously examined too
2. Quantification of ecological
   the ecological variables haven’t been counted, for example for weaver birds, are the seed patchy and food dispersed?
3. Cause and effort
   E.g. weaver fish with a diet of seeds go around in flocks. Our explanation was seed eating selects for flocking as its best for finding patchy food. But it could easily be predation selects for flocking and seed eating is forced as it is an abundant food source
4. Alternative adaptive peaks and none-adaptive differences
   Tempting to assume differences are always adaptations, but easily could be alternative solutions to the same pressures

Question 32

What 3 improvements to the comparative method did Clutton-Brock and Harvey make when studying primate social arrangement?

Answer 32

1. they measured behaviour and morphology on a continuous scale rather than categories
2. they considered alternative hypotheses, and used multivariate stats to see different ecological variables of each trait
3. Used different genera as independent data points for analysis, rather than species to reduce the problem of similarity through common ancestry

Question 33

How would the home range of insectivores or Frugivores vary from leaf eating primates of the same size?

Answer 33

Insectivores and Frugivores are specialist feeders and their food isn’t as common or abundant as leaf eaters.

Therefore, their home ranges are larger as their food is more dispersed

Question 34

What are the 2 hypotheses for sexual dimorphism in body weight in primates?

Answer 34

1. Could enable males and females to have different food niches – avoid competition
   (BUT If this were true, dimorphism would be greatest in monogamous species)
2. Could have evolved through sexual selection; males large because it means they can get more females (Supported by the comparative body weight)

Question 35

What are the 2 hypotheses for sexual dimorphism in tooth size in primates?

Answer 35

Males have larger teeth: 2 hypotheses

1. Defence of group against predators
2. Competition with other males
   - the problem with this as body weight is a confounding variable, tooth size could just reflect body size
   - sexual selection theory is supported for evolution of large teeth in males, nevertheless we can’t exclude predator defence, because maybe the harem forming animals are the ones at risk from predators

Conclusion: both have influenced evolution of tooth size. Also differences in tooth size could prevent food overlap and competition

Even with careful analysis it may be difficult to tease to the effect of multiple variables on evolution

Question 36

Why do male chimpanzees have smaller testes than male gorillas and orang-utans

Answer 36

The heaviest primates are the gorilla and orang-utan have breeding systems that involve one male monopolizing mating with several females, and have testes that weigh between 30-35g respectively

Smaller primates such as chimpanzees have a breeding system of multiple males copulating with each oestrous female, and testes weighing 120g

It would be logical that the gorillas who only need to ejaculate enough to fertilize the females have smaller balls than the chimps, as the chimp’s sperm has to compete with other sperm and therefore increased production is favoured

Question 37

Describe the experiment and outcomes of Tinbergen’s observations of black headed gulls on sand dunes

Answer 37

Parent gulls were seen picking up and removing egg shells from nest. This is crucial to survival of chicks as the insides of the egg are white and very conspicuous (the parents and chicks themselves are well camouflaged)

Tinbergen carried out an experiment:
- Painted hens eggs like the gulls eggs, then put white broken eggs next to them.
This confirmed that the eggs are targeted much more when shells are near them

However , the parents only remove the shell 1 or 2 hours after the breaking. The delay is due to the risk of leaving a newly hatched chick – wet down is easily swallowed by neighbours, so they wait until chick is dry

This is a trade-off between camouflage and chick care

Question 38

Give a comparison bird to the behaviour of the black headed gulls observed by Tinbergen

Answer 38

In comparison an oystercatcher who also nest in the dunes. also needs to remove the shell but doesn’t have the threat of cannibalism as it nests alone, therefore removes the shell almost straight away

Question 39

What is the goal of an optimality model?

Answer 39

an optimality model seeks to predict which particular trade-off between costs and benefits will give the maximum net benefit to the individual

Question 40

What are Incidental groups and Social groups

Answer 40

Incidental groups: in a common place e.g. using a common food resource or water or roost site

Social groups:

• reflect intrinsic sociability
• common fish, birds and mammals
• vary in sixe, permanence, and function
• may be single or multiple species

Question 41

What is local enhancement?

Answer 41

The process by which an individual’s attention is directed to the location of food by other group members

i.e., learning what to eat or where to eat by observing others.

E.g. family group, or partner finding food and showing and teaching young

Question 42

Give an example of local enhancement

Answer 42

Great Tits (Parus major)

Kept in aviaries with artificial ‘trees’, where at the end of each ‘branch’ was a container (N = 60) where birds could search for concealed food

Experiment:
Recorded amount of food found by each bird in a fixed time period

Tested birds alone, in pairs, in flocks of 4

Results 
% of birds finding food/15 min period:
single bird = 25%
two birds = 40%
four birds = 75%

Conclusion = Local Enhancement

Question 43

Describe how foraging in a flock can get a subordinate bird less food but it is still an advantage to be in a flock?

Answer 43

Dominant birds usually obtained more food than when alone; degree of advantage increased with rank (dominant birds took over lower-ranking birds that found food)

Lowest ranking birds obtained about same or slightly less food than when alone

Probability of flock finding no food = 20%
Probability of subordinate finding no food = 58%

So why join a flock?
Dominant individuals benefit by obtaining more food, and subordinates benefit by a reduced probability of getting no food at all (risk-minimization)

Question 44

What is meant by a group acting as an information centre?

Answer 44

Groups or colonies may be advantageous if individuals share information about the location of ephemeral patches of food

Question 45

Give an example of a group acting as an information centre

Answer 45

Juvenile raven roost on Anglesey

Birds seen to go off separately and feed in the day but lots come back to a communal roost

Experiment:

• Sheep, hare & squirrel carcasses 2-30km from roost baited with coloured beads; carcass eaten could be told from droppings
• Beads from the same carcass found in pellets appear in same part of roost
• Number of birds leaving roost and arriving at carcass increase together over 5 days – animals are learning from an individual that there’s food in a certain location. Flight direction matched carcass bait.

Conclude: same birds leaving & arriving, and evidence for recruitment from a single bird :

• The same bird (not necessarily the recruiter)
• Gave pre-roost evening displays
• Initiated morning departures, with vocalizations
• Was first at carcass
• Appeared dominant to others at carcass

Question 46

Give 3 downsides to foraging in a group

Answer 46

1. Subordinates may not get food
2. Search time: benefit of reduced search time reaches asymptote quickly as group size increases.
   - In large groups individuals may interfere with each other
   - individual search areas may overlap
   - more individuals may increase the evasive action of pre
3. Energy needs:
   - energy (i.e., food) available is limited
   - energy needs continue to increase with increasing group size
   - As group size increases, energy needs will exceed availability

Question 47

Why might a group be more vulnerable to predators once they reach a certain size?

Answer 47

If groups get too large, individuals may actually be more vulnerable to predators.

E.g.
Crisler (1956) - Wolves captured caribou in very large herds more easily than caribou in smaller herds; caribou in large herds may not be able to see approaching wolves.

Question 48

Why might a group be more vulnerable to predators once they reach a certain size?

Answer 48

If groups get too large, individuals may actually be more vulnerable to predators.

E.g.
Crisler (1956) - Wolves captured caribou in very large herds more easily than caribou in smaller herds; caribou in large herds may not be able to see approaching wolves.