2. Behavioural Adaptations for Survival

Question 1

What is Anti-predator behaviour

Answer 1

Adaptations evolved in prey animals in response to predation threat.
“It is hard to pass on your genes when you
are dead”
(Alcock, 2009)

Question 2

Example of anti predation behaviour

Answer 2

Canyon treefrogs rely on camouflage to protect
themselves from predators, which means they must pick the right rocks to which they cling tightly without movig

Question 3

For the Darwinian Theory & Ultimate Hypotheses,
Evolutionary change is inevitable if these conditions are met:

Answer 3

Variation: members of a species differ in some
of their characteristics
Heredity: parents are able to pass on some of
their distinctive characteristics to their offspring
Differences in Reproductive Success: some
individuals have more surviving offspring than
others in their population, thanks to their
distinctive characteristics

Question 4

What is mobbing behaviour

Answer 4

Whenever a potential consumer of eggs or chicks comes close to nesting gulls they usually react strongly

Question 5

What may be the Ultimate Cause of Mobbing Behaviour

Answer 5

Use the adaptationist approach
Is mobbing response of gulls an adaptive
product of natural selection?
Hypothesis: mobbing behaviour distracts
predators, reducing the chance that they will
find the mobbers’ offspring, which would boost
the fitness of the mobbing parent gulls

Question 6

What is adaptation in Anti-predator behaviour

Answer 6

A hereditary trait that either:
Spread through the population in the past and has been maintained by natural selection to the present
Is currently spreading relative to alternative traits because of natural selection

Question 7

What is the Cost-Benefit Approach

Answer 7

Tool borrowed from Economics
Analyse phenotypes in terms of their fitness
benefits and fitness costs

Question 8

Whats the fitness benefit in the cost benefit approach

Answer 8

The positive effect of a trait on the number of surviving offspring produced by an individual, or the number of copies of its alleles that it contributes to the next generation

Question 9

Whats the fitness cost in the cost benefit approach

Answer 9

The damaging effects of the trait on measures of individual genetic success

Question 10

What are the significant fitness costs of mobbing behaviour

Answer 10

• Time and energy spent diving at intruders
• Loss of life to predator
• Attraction of other predators to nest

Question 11

Why can mobbing behaviour not be an adaptation

Answer 11

To be considered an adaptation fitness
benefits must exceed fitness costs

Question 12

Eg of observational work in mobbing and the cost benefit approach

Answer 12

• Egg-eating carrion crows have to continually face swooping black-headed gulls
• While being mobbed they cannot easily look for eggs
• Distracted crows less likely to find their prey
• Probable fitness benefit exists for mobbing behaviour
• Fitness benefit likely exceeds fitness cost as crows do not attack/injure adult gulls

Question 13

Whats the comparative method

Answer 13

• Involves testing predictions about the evolution of a trait by looking at species other than the one whose characteristics are under investigation
• If a trait is adaptive for one species it should also evolve in other species subject to the same selection pressures
• If the selection pressure disappears the trait should also disappear (e.g. if fitness costs outweigh fitness benefits)

Question 14

Hypothesis for mobbing in black headed gulls in the comparative method

Answer 14

mobbing by ground-nesting black-headed gulls is a response to predation pressure
* Cost of mobbing outweighed by benefits
derived from distracting predators
* If predators not a major problem for a species
then the benefits of mobbing would be reduced

Question 15

Example of divergent evolution

Answer 15

Cliff nesting gulls currently have fewer nest predators.
Change in nesting environment - change in predation pressure.
Evolutionary result should have been a shift away from ancestral mbbing behaviour.

Question 16

What is convergent evolution

Answer 16

Species from different evolutionary lineages
that experience similar selection pressures
can be predicted to evolve similar traits

Question 17

What is divergent evolution

Answer 17

What occurs when two groups of the same species evolve different traits within those groups in order to accommodate for differing environmental and social pressures.

Question 18

What is Optimality Theory

Answer 18

Optimal behavior is defined as an action that maximizes the difference between the costs (C) and benefits (B) of that decision. Three primary variables are used in optimality models of behavior: decisions, currency, and constraints.
Attempts to make precise predictions about
the net fitness benefit (B – C) of a trait

Question 19

Example of Optimality Theory

Answer 19

Northern bobwhite quail spend winter in small groups.
Members of larger coveys safer from attack.
Relatively large groups move about more
Anti-predator benefits offset to some
degree by increased competition for food in larger groups

Birds in intermediate-sized groups appear
to have greatest net fitness gain
* Greatest daily survival rate
* Lowest mean daily movement

Question 20

Example of puzzling anti predator behaviour

Answer 20

Some species seem to try to make themselves obvious to their predators.
Tephritid fly that habitually waves its banded wings as if trying to catch the attention of its predator (jumping spider)
Deception Hypothesis: when fly waves its wings it
resembles a spider giving an aggressive leg waving display