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Flashcards in THEME 1 Deck (48):
1

What does behavioural ecology aim to assess?

the effects of evolutionary and environmental factors on animal behaviour

2

What is behavioural ecology?

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

3

What are Tinbergen's 4 whys?

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)

4

Give an examples of Tinbergen's 4 whys in starlings

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

5

Why do female goats have horns?

- 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)

6

Give 3 ways proximity loggers record behaviour and physiology

Proximity loggers

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

7

Is there evidence for individual selection?

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

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?

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

9

What did Tinbergen study?

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.

10

Give the modern version of Tinbergen's questions

Motivation – Proximate/immediate causation

Development – in the individual

Function – What problem does it solve?

Evolution – Ultimate causation

11

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

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

12

Describe how speciation could occur in finches on Daphne Island

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

13

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

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

14

What is Optimization prediction

behaviour maximises fitness

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

15

What is the Optimization criterion

maximum net benefit = max(b-c)

16

Give the benefits and costs of foraging

Foraging (= searching + handling food)

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

17

What are allocation costs and opportunity costs?

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

opportunity costs = cost of not performing other behaviours

18

What are Darwin's 5 points?

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

19

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

- 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

20

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

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)

21

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

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

22

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

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)

23

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

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

24

What is phenotypic plasticity?

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

25

Give an example of phenotypic plasticity in great tits

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)

26

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

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

27

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

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


28

Describe the components of a lion pride

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.

29

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

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

30

What are the 3 ways to test behaviour?

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

31

Give 4 downfalls to the comparative method

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

32

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

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

33

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

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

34

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

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)

35

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

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

36

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

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

37

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

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

38

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

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

39

What is the goal of an optimality model?

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

40

What are Incidental groups and Social groups

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

41

What is local enhancement?

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

42

Give an example of local enhancement

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

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?

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)

44

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

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

45

Give an example of a group acting as an information centre

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

46

Give 3 downsides to foraging in a group

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

47

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

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.

48

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

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.