Evolution of Adaptations (L8) T2

Question 1

What is an adaptation?

Answer 1

Trait caused by a mutation that increases reproductive success. It is maintained in a population by natural selection.

Question 2

Indirect measures of reproductive success

Answer 2

1. Researchers test whether the trait serves a function correlated with improvement in lifetime fitness.
2. Examples: Survival chances, access to food, access to living space, efficiency of locomotion.

Question 3

Direct measures of reproductive success

Answer 3

1. Researchers test whether the trait yields added opportunities to reproduce successfully.
2. Examples: production of gametes, rate of copulation.
3. Production of fertilized eggs, newborn offspring,
4. Production of offspring that reach age of independence, that reach the age of reproduction during one breeding season, and that reach the age of reproduction over the individual’s lifetime.

Question 4

What is the most important measure of reproductive success?

Answer 4

Number of reproducing descendants; all other measures should correlate with this to varying degrees.

Question 5

Why birds mob: Self defense hypothesis

Answer 5

Mobbing birds increases their survival by assessing the enemy and perhaps driving it away.

Prediction: mobbing should occur at all times of year.

Problem: mobbing occurs primarily during breeding season.

Question 6

Why birds mob: Mating advertisement hypothesis

Answer 6

Individuals can signal their quality as potential mates to others of the opposite sex.

Prediction: Both mated and unmated adults will mob.

Question 7

Why birds mob: Predator distraction or parental care hypothesis

Answer 7

Parents confuse and distract predators intent on finding and eating their offspring.

Prediction: only mated adults, especially those with young, will mob.

Question 8

Conclusions for mobbing

Answer 8

Mobbing is the most useful for adults with young.

Question 9

Divergent evolution

Answer 9

The process by which an interbreeding population or species diverges into two or more descendant species, resulting in once similar or related species to become more and more dissimilar.

Question 10

Convergent evolution

Answer 10

A kind of evolution wherein organisms evolve structures that have similar (analogous) structures or functions in spite of their evolutionary ancestors being very dissimilar or unrelated.

Question 11

Cost-benefit approach

Answer 11

All traits have both positive and negative effects on individual reproductive success.

1. Fitness costs: when A mobs, B comes and eats A’s offspring
2. Fitness benefits: mobbing saves offspring from predation.

Question 12

Optimality theory

Answer 12

Assumes that current (evolved) behavioral traits are those that contribute the most to fitness.

Question 13

Evolutionary Stable Strategy (ESS)

Answer 13

The presence of two or more behavioral strategies in a population, which are maintained by a density-dependent natural selection.

Question 14

Criticisms of the adaptationist approach

Answer 14

Some criticize the belief that all components of an organism are perfectly adapted products of natural selection.