Lecture 18-22: Barber Flashcards

1
Q

What is the comparative approach to behavioural ecology?

A

Similarities between animals due to native environment, then map this to phylogeny. - Ecological factors make a large difference

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2
Q

How are mathematical models used in behavioural ecology?

A

Analysing trade-offs (cost-benefit analysis) Works on the assumptions that the current generation is the offspring of the individuals in the previous generation who made the correct decisions.

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3
Q

Explain the basis behind kin selection and inclusive fitness:

A

Helping others which are related to you increases your future fitness despite possibly decrease the individuals in the present moment. Inclusive fitness: success of all genes you share with others which will be transmitted to future generations

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4
Q

What serengeti lion behaviours have been studied in behvaioural ecology?

A

Females entering oestrus at the same time Low birth rate All young killed by new males in a group

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5
Q

What was discovered about female lions entering oestrus at the same time?

A

Caused by pheromones –> synchronisation Functional benefit: synchronous cubs (brothers) which leads to increased survival, synchronous suckling

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6
Q

What was discovered about the low birth rate in female lions?

A

Caused by the fact there is a discrete period of ovulation. Functional purpose: increases paternity uncertainty, therefore reducing competition - best sperm will win

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7
Q

What was discovered about why new males kill all the young?

A

Functional: females come into oestrus faster without cubs, previous cubs would create competition for new cubs Causal: males kill cubs, hormonal change in females leads to abortion.

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8
Q

What evidence is there for a genetic component to behaviour?

A

Genetic mutants: radiation and chemicals causes different behavioural mutants Artificial selection: able to select for behavioural traits which then leads to more extreme results in the next generation. Different populations have genetic differences –> differences in behaviour.

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9
Q

What examples are there of different behaviours in different populations of the same species.

A

Garter snakes prey preferences depending on location (differences in food availability) shown by presence of slugs in diet Migratory behaviour of blackcaps (all german birds migrate, 20% english, no cape-verde birds), hybrid of german and cape verde birds –> 60% migratory (dominant gene)

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10
Q

What is the unit of natural selection?

A

Genes -create phenotypes which can be selected on

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11
Q

Please explain the modern darwinian theory?

A
  1. Organisms have genes which code for protein synthesis 2. These proteins regulate development and therefore influence behaviour 3. Many genes exist in different forms (alleles) which code for slightly different outputs 4. The different alleles lead to differences in behaviour and therefore variation 5. Any allele which makes more surviving copies of itself will eventually become fixed in the population 6. Natural selection is the differential survival of alternative alleles.
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12
Q

How are economic decisions made in animals?

A

The best achievable balance of costs and benefits - optimal behaviour –> most offspring - sub-optimal behaviour –> decreased levels of offspring

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13
Q

What are the key concepts behind economic decision making?

A

All behaviour takes time and costs energy which cannot be re-allocated. Multi-tasking causes a loss of efficiency

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14
Q

How does corvid foraging strategies demonstrate economic decision making?

A

Have to drop each shell-fish repeatedly from a height to open them. 15% of drops are made at the peak 85% of drops are made just after (see where it lands) Want to use the minimum possible energy.

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15
Q

How can you analyse optimal foraging?

A

Analyse actions in the view of future reproductive success (FRS) Could use net rate of energetic energy (gamma) Foraging efficiency = energy gained / handling time Starvation / predation avoidance

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16
Q

How can net rate of energetic gain be used to analyse optimal foraging?

A

Try to maximise energy gained from time spent foraging. Try to minimise time spent acquiring energy Energy gained - energy used= gamma

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17
Q

What species feed differently depending on the cost-benefit analysis?

A

Kestrels: either flight hunting or perch hunting - Flight hunting used in winter because despite increased cost there are huge increases in gain - Perch hunting used when food more available.

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18
Q

How can starvation / predation avoidance be used to analyse optimal foraging?

A

Risk of predation for increased quality food. Juncos in winter either get garunteed poor quality food and will starve or risk becoming prey in order to get better quality food.

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19
Q

What does optimal foraging depend on?

A

Best option depends on handling time, cost, appetite, gape limitations.

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20
Q

How do redshanks know which prey to chose?

A

Sometimes feed only on large worms, sometimes feed on both- depends on prey availability. - Short worms rejected when large worms are common. Big worms always taken.

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21
Q

How can you use algebra to analyse which prey a redshank should choose?

A

Large prey (1) are more profitable than small prey (2) Energy gained (1)/ handing (1) > Energy gained (2) / handling (2) Small prey should be taken when energy gained exceeds the energy gained from rejected it and searching for a large one. E2/H2 > E1/S1 + H2 (increased earch = less profit

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22
Q

What are the assumptions of the model for redshank foraging?

A

Should either specialise on most profitable item or eat prey as they come - no partial preferences. Will pick the correct prey because theyre the offspring of successful parents.

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23
Q

How can a conveyor belt be used to test partial preferences?

A

Large meal worms which are twice as profitable as smaller Change the encounter rate of large worms and then map the switch point Observe partial preferences.

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24
Q

What is the marginal value theorem?

A

Used to determine how long individuals should persevere when experiencing diminishing return for increased handling time

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25
Q

What species are used to test marginal value theorem?

A

Starlings and Leatherjackets - tradeoff between protecting chicks and foraging for them - limited by the amount of food they can carry (rate of fill decreases with filling)

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26
Q

How many prey items should be loaded before returning when diminishing return occurs?

A

Insert diagram Gain curve diminishes with increased beak load - When the line touches the gain curve = maximum

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27
Q

How does the amount of prey items taken depend on habitat quality?

A

Diagram Higher the quality- more time which should be spent searching

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28
Q

How does the amount of prey taken depend on travel time?

A

Diagram Further they have to travel = more searching time needs to be done (load needs to be bigger) to make it worth it. Decreased travelling time = spend less time searching

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29
Q

How can you manipulate optimal foraging with a feeder?

A

Experimental data fits what is predicted

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30
Q

How are reproductive decisions made in dungflies?

A

Males compete for females on cowpats When more than 1 male mates with a female, the final male fertilises about 80% of eggs- depending on copulation time (males can be dislodged) Increased time copulating –> increased fertilisation

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31
Q

When should male dungflies leave a female to find another mate?

A

Copulate for 100s = 100% fertilisation, 40s= 90% Time spent copulating depends on the female availability.

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32
Q

What resources are competed for?

A

Food, space (territory, nests), mates, scare materials (nutrients)

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33
Q

What are the types of competition?

A

Interference or Resource defence

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34
Q

Describe the different types of interference competitions?

A

Exploitation: resources already removed by other competitors Scramble: intereferences over each resource item, faster responder wins, no aggression just jostling for position Contest: aggressive interaction over each resource, winner has the opportunity for excluding items and defending –> Resource defence

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35
Q

How can starlings demonstrate competition?

A

Single bird in a habitat –> no interference Two birds in a dispersed patch –> no serious interference ( food still plentiful) Two birds in a clumped habitat –> some interference Many birds in a clumped habitat –> increased interference - one dominant bird can exclude resource availability.

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36
Q

How is the amount of interference proportional to resource distribution?

A

Clumped resources –> increased encounters due to increased density of competitors (>1 competitor decides to go for the same item –> aggression)

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37
Q

How do brown hares demonstrate competition?

A

Aggregate in groups for feeding –> improved vigilance With increased group size there is also increased aggression Insert diagram

38
Q

How does the temporal distribution of resources affect competition?

A

Temporal clumping (lots at one time) leads to less competition because it is hard for one individual to dominate. Spatial distribution leads to greater competition.

39
Q

How does the ideal free distribution (IFD) work?

A

Distribution of competitors in fragmented environment, where predators can move about and have information about environment and resource avaliability. –> positioning around resources –> number of competitors in each patch cannot be improved

40
Q

What is a good analogy to IFD?

A

Supermarket queues- which one is shortest, which one is fastest?

41
Q

How does IFD change with individuals?

A

Individual reward diminishes with increased number of competitors Rich habitat will fill up faster, because an equal number of competitors –> more reward Some animals move to a poorer environment which is less exploited. Insert diagram.

42
Q

Describe the factors affecting the IFD for equal competitors

A

N= number of equal competitors Resources items arrive at different rates in different places (Q1 at patch 1, Q2 at patch 2, Q3 at patch 3) N1 in patch 1, N2 in patch 2, N3 in patch 3 Items gained = Gi which is constant in IFD

43
Q

How does items gained (Gi) depend on competitor number(N) and input rate (Q)?

A

Gi = Qi/Ni with Gi being constant –> Gi= C Ni= Qi/ C

44
Q

How do sticklebacks demonstrate IFD?

A

In a tank of 6 sticklebacks Two ends: Q1 = 2x Q2 N=4 at Patch 1, N=2 at patch 2 If you swap ends –> fish swap ends (after taking time to realise)

45
Q

How does IFD change with unequal competitors?

A

Competitor 1: competitive weight = 2 Competitor 2: competitive weight = 1 Therefore competitor 1 gets twice as much food.

46
Q

How will unequal competitors distribute themselves?

A

2 competitor 1’s and 4 competitor 2’s- total weight = 8 1’s get 2/8, 2’s get 1/8 Can distribute themselves differently with the same energetic distribution 1,1:2,2,2,2, or 1,2,2:1,2,2

47
Q

How can gall aphids demonstrate unequal competition?

A

Large leaf stems can support 7x as many eggs as a small leaf. Larger leaves are occupied first. Next competitor will have choice between singular occupation on a small leaf or co-occupying larger leaves. - Will share with 1 or 2 = still beneficial -Reproductive success decreases with decreasing density, but increases with increasing habitat quality. Insert diagram

48
Q

What is despotic distribution?

A

Territories form in high quality environments when aggressive guarding of resources occurs. - territories fill until no more competitors can enter (A) - competitors go to lower quality territories –> fill up (B) Any further competitors may just float (no territory) Insert diagram

49
Q

How does the distribution of competitors change under monopolised resource conditions?

A

Monopoliser reaps benefits, but must spend energy protecting resources (territory guarding, fighting). If costs outweigh benefits then resource should not be defended, but it should be if benefit outweighs costs. This also depends on habitat quality.

50
Q

Does this depend on the environment.

A

Some environments require an exponential cost to defend resources e.g. walking perimeter Some environments the costs are less / increase in a linear manner.

51
Q

Explain what an arms race is?

A

Constant evolutionary change with one species changing to keep up / overtake another. Follows red queen hypothesis- having to run faster to keep still.

52
Q

How does the predation sequence work?

A

The predator and prey must overlap temporally and spatially. There are a number of paths with predators and prey which can lead to escape, death, consumption Must pass through a series of stages shown in the picture

53
Q

What is the probability of the predation sequence occurring in each different path?

A

Anti-predator behaviour can develop at any level.

54
Q

How would you reduce the chances of encounter?

A

Reduce / minimise the zone of overlap - Habitat switching: switch to a different (more protected) habitat with increased predators —> benefit: less chance of being predated —> Cost: reduced growth rate

55
Q

Define crypsis:

A

Pattern of colouration resembling a random sample of the visual background as perceived by a predator when the prey is most vulnerable predator.

56
Q

What species are a good example of crypsis?

A

Moths with melenistic (dark) and normal (light) morphs - frequency of morphs depend on environment - can experiment with the effectiveness of disruption camouflage.

57
Q

How are moths used as an example of crypsis, specifically disruption camouflage.

A

Pinned artifical moths (with a meal worm) of varying patterns to trees and then monitored the survival Disruptive > Camouflage > Solid

58
Q

What is the optimal diet model?

A

A predator searches for Ts seconds Encounters cryptic prey (A) and non-cryptic prey (B) at rates lambda(A) and lambda(B) and gains E(A) and E(2) calories. Non-food items (C) which A camouflages as contain 0 calories. Handling time: H(A), H(2), non food H(C) Generally EA/HA > EB/HB but A is cryptic

59
Q

What are the different types of predator and how do they operate differently with the optimal diet model- Generalistic predator

A

Generalistic predator: E= Ts(lambdaEA + lambdaEB) —-> Requires total time T= Ts + Ts(lambdaHA + lambdaHB + lambdaHC) —-> Total profit = E/T = Lambda EA + Lambda EB / 1 + Ts(lambdaHA+lambdaHB+lambdaHC)

60
Q

What are the different types of predator and how do they operate differently with the optimal diet model- Specialist predator

A

Only feeds on less profitable but non-cryptic prey Energy gain(E/T)= lambdaEB/ 1+ lambdaHB As long as E/T for a specialist predator > generalist predator- then it is more profitable to eat only non-cryptic prey. However if E/T= lambdaEA/ 1+lambdaHA+lambdaHC > E/T for a generalist then a predator should specialise on cryptic prey.

61
Q

What factors can affect what a predator should choose in terms of prey?

A

Length of handling time for non-food item Availability of each prey type (especially prey A)

62
Q

What are rapid inducible defences from predators e.g. crucian carp?

A

Predators or even their odour is introduced to the carps environment –> carps developing deeper bodies. This is due to phenotypic plasticity (which may be selected for during evolution- epigenetic effect)

63
Q

What is brood parasitism?

A

>80 species of birds (mainly cuckoos) use other birds to raise their young - lay eggs in different species nests - eggs patterned to match host (mother specialises on a species of host. Parasite gains fitness, host loses fitness —> should cause counter-adaptations in parasites.

64
Q

How does a mother parasite discretely lay her egg in another nest?

A

Female cuckoo watches host build nest –> lays an egg in that nest –> removes a single egg at the same time –> cuckoo chick hatches and ejects all other eggs, because it has a shorter incubation time.

65
Q

How has it been shown that cuckoos respond to selection?

A

Model cuckoo eggs added to host nests Egg will be rejected if: poor match, laid before clutch laying, laid at dawn, cuckoo model near. –> visual appearance and temporal aspects of eggs must be selected for in cuckoo adaptations.

66
Q

What depends on how the well the cuckoos mimic the colours of the host eggs?

A

Depends on discrimination ability and different gentes (host specialisism) –> dunnocks do not discriminate so cuckoos dont bother –> meadow pips do discriminate –> cuckoos mimic eggs A product of co-evolution - Host species learn to remove odd eggs - New hosts (dunnocks) or those species which have never been hosts have not evolved this ability.

67
Q

How does possible cuckoo hosts change with co-evolution and rejection of eggs?

A

Birds with higher rejection rates are likely to have been previous hosts. Hosts which are moving towards the right of the graph will eventually be used less. Select for hosts with less rejection –> adaptation in this species Old hosts may eventually lose adaptation if not used by cuckoos for a while –> possible host again.

68
Q

What are the different ways animals group together?

A

Some naturally solitary but aggregate for feeding (Hares) Grouping depending on predator abundance Benefits must outweigh the costs

69
Q

What are the benefits of living in a group- Antipredator?

A

Improved vigilance- many eyes hypothesis Risk dilution- safety in numbers Attack dilution Predator swamping

70
Q

How is risk dilution and safety in numbers, a benefit of grouping

A

predator avoidance ——> clumped prey maybe harder for predator to locate ——> decreased probability of an individual entering a predators detection zone

71
Q

How is attack dilution a benefit of grouping?

A

Predators can only catch a limited amount of prey - lions will only catch one wildebeest Per capita risk is decreased: individual risk = 1/ number of individuals Also harder to attack a group than an individual - Some predators do however specialise on hunting groups (humpback whales, killer whales, humans)

72
Q

How is predator swamping a benefit of grouping?

A

Temporal swamping - If all individuals leave the home / nest at the same time only a few can be caught due to the handling time. - Bats leaving nests - Cicadas only leave underground nests every 13 or 17 years.

73
Q

How is predator confusion a benefit of grouping?

A

Attack success on larger groups decreases faster than 1/N Aggergated prey move synchronously to overwhelm the sensory ability of predators. Most effective when the prey all looks and acts the same Increasing school size –> decreased capture

74
Q

What other benefits are produced from increased group size?

A

Increased detection distance Communal defence: mobbing, radial protection (elephants), radial protection (mongoose), increased numbers = increased protection

75
Q

What are the overall affects of all anti-predator benefits on predator prey interactions?

A
76
Q

What links are there between foraging and increased group size?

A

Individuals are able to forage for greater periods due to group vigilance. Communication between individuals –> easier locating of food Improve chance of catching prey, increased search area Forage area copying –> decreased time to locate prey. Information centre hypothesis Larger groups = larger kill - gazelle –> wildebeest Organisation and role specialisation.

77
Q

Please describe the information centre hypothesis?

A

Communally roosting birds gauge foraging success of roost mates - starlings - If 2 flocks are roosted together, one flock can tell the other flock where a resource is. —> shown by experiments where 2 flocks are trained in finding different supplies –> share information with the other flock.

78
Q

Please describe how organisation and role specialization change with group size?

A

Development of individual roles: hunt initiators, capturers Hunt success rate increases with group size, but individual gain decreases.

79
Q

Why do individuals recruit others to a foraging area?

A

If group benefits outweigh costs then the individuals will actively recruit other members to the foraging site. It does however depend on how divisible the resource (food) is- slice of bread is harder to share than crumbs.

This is shown by chirrup rate

80
Q

What are the benefits of increased group size when it comes to mating?

A

Access to and assessment of a large number of potential mates. —> reduced travel and assessment —> Leks: females can compare multiple males ———–> Larger Leks have better males

81
Q

What are the anti-parasite benefits of large group sized?

A

Parasites act like predators. Each individual is less likely to be attacked by a parasite. Individuals in the centre of a group have more protection.

82
Q

What are the energetic benefits of living in a group?

A

Locomotory benefits: pelicans fly in a V formation which uses less energy depending on position –> rotation. Thermal benefits: huddle for warmth

83
Q

Do all individuals benefit equally?

A

If an individual stands out it is far easier targeted by predators. Extremes of a population will stand out more –> more likely to be predated.

84
Q

Are all members of a group equally protected?

A

Protection depends on position- selfish herd theory Proven by the shoaling fish experiment

85
Q

Please explain the selfish herd theory:

A

Peripheral positions are most risky (predation) –> individuals will always try to head further inwards Front positions are risky but rewarding –> increased cost and benfit –> discover new environment, food or predators

86
Q

Please explain the shoaling fish experiment?

A

Removed sample of fish population and starved for 24hr If you reintroduce them, then go straight to front position —> Increased feeding —> Move further back when satiated —> Other fish move forwards due to hunger.

87
Q

What are the costs of grouping?

A

Can be direct or indirect (effort of avoiding a cost) Foraging costs Antipredator costs

88
Q

What are the costs possible in foraging?

A

Competition Kleptoparasitism- food stealing –> risk of injury, aggression, loss of prey Dominance hierarchy –> aggression Interference or pseudo-interference View blocking: outside or front has the best view

89
Q

What are the antipredator costs?

A

Possibly easier to detect( smell or sight) More likely to be targeted possibly Confusion between individuals –> advantage for predator Larger groups forage in riskier areas

90
Q

What are the other costs of grouping?

A

Misdirected parental care Increased pathogen transfer –> contagious parasites and pathogens spread between individuals in close contact.