Mechanisms of Adaption (Siva-Jothy)

Question 1

Adaption

Answer 1

Evolutionary change that fits an animal to its habit or habitat. It is non random and directional.

Question 2

Ways to recognise adaption

Answer 2

• Optimality studies
• Comparative studies
• Experimental manipulations; manipulate what you think is causal (not correlational). If there’s no manipulation, it is NOT an experiment.

Question 3

Comparative approach

Answer 3

Do animals with similar lifestyles have similar traits? E.g. echolocation

Question 4

Experimental manipulations

Answer 4

If a trait is an adaptation, then changing the trait will change its adaptive value

Question 5

Adaptation? Genetic Drift, Mutations, Meiotic Drive, Molecular Drive?

Answer 5

All of these can cause evolutionary change, because they produce a change in gene frequencies but the change is random. Adaptations are directional so therefore none of these can be a mechanism for adaptation.

Question 6

Adaptation? Inheritance of characteristics?

Answer 6

This can produce adaptive change but only by chance, it is just as likely to produce a non-adaptive change. Also adaptive changes cannot be passed on.

Question 7

Adaptation? Selection?

Answer 7

Better adapted individuals survive longer and mate more frequently so leave more offspring.
Poorly adapted individuals die sooner or fail to mate so leave fewer offspring.

There are 3 factors necessary for selection

• Multiplication
• Variation
• Inheritance

Question 8

Selection - multiplication

Answer 8

Multiplication leads to a struggle for existence, as there will not be enough resources or space for all members of the population.

Question 9

Selection - Inheritance

Answer 9

Selection + inheritance = adaption

Question 10

Selection - Variation

Answer 10

Some have better characteristics to survive in the habitat better than others.
Variation + struggle for existence = differential survival and reproduction (selection).

Question 11

Discontinuous variation

Answer 11

Determined by one set of genes, e.g. colour morphs.

Question 12

Continuous variation

Answer 12

Determined by multiple sets of genes (polygenic inheritance), e.g. body size.

Question 13

Where does new variation come from?

Answer 13

Recombination
-Not evolution as it doesn’t lead to a gene frequency change.

Mutation
-Mutation creates variation, which is random in direction. Selection provides direction to adaptive change. This means mutation is then central mechanism but is not the mechanism on its own.