Life History Evolution

Question 0

Life history trait

Answer 0

Those directly associated with growth, maintenance and reproduction

Question 1

Life history

Answer 1

Lifetime pattern of energy allocation to growth, maintenance and reproduction

Question 2

Life history trade-off

Answer 2

Ideally an organism would maximize all fitness components across its entire life history but resources and time are limited, investment in one aspect of fitness takes away from another = a trade-off

Question 3

Senescence

Answer 3

Late-life decline in fertility and probability of survival

Question 4

Evolutionary theory of aging

Answer 4

Failure to repair damage caused by: accumulation of deleterious mutations (mutation accumulation hypothesis) or trade-offs between repair and reproduction (antagonistic pleiotropy hypothesis)

Question 5

Mutation accumulation hypothesis

Answer 5

Natural selection is weak late in life, alleles expressed late in life (after reproduction has already occurred) have little impact on fitness
Alleles:
Mildly deleterious may persist in mutation selection balance or neutral may rise to high frequency by genetic drift

Question 6

Antagonistic pleiotropy hypothesis

Answer 6

Alleles that increase early reproduction also cause early senescence (= trade-off between early reproductive success and late-life reproductive success)
Alleles:
Beneficial may rise to high frequency by selection, benefits of early reproduction must outweigh costs of early death

Question 7

Pleiotropy

Answer 7

Single gene affects multiple traits

Question 8

Lack’s hypothesis

Answer 8

Selection should favor a clutch size that produces the most surviving offspring - intermediate optimal clutch size

Question 9

Smaller than expected clutch size reasons and factors scientists would need to measure to understand clutch size

Answer 9

Trade-off between parents current and future reproduction (smaller clutches may allow for greater reproduction by parent in next year),
Trade-off between quantity and quality of surviving offspring (smaller clutch may allow each offspring to have higher reproductive success when they are adults)
Need to measure clutch size, offspring size, offspring reproductive capability

Question 10

Life history traits not perfectly optimized

Answer 10

Not enough time or genetic variation to evolve toward new optimum, constraints that impede evolution

Question 11

Life history trait heritability

Answer 11

Closely related to fitness so have lower heritability than other traits but often still have genetic variation (time to rid deleterious alleles or fix beneficial alleles, genetic variation, etc)