Life History Evolution

Life history

pattern of allocation of time and energy to various fundamental activities

• growth

• repair of damaged tissues

• reproduction

Life histories can be modeled as

age specific probabilities of survival and reproduction characteristics of a species

semelparous

individuals reproduce once and then die

how to calculate reproductive sucess with semeparous individuals?

R = LM

L = probability of female survival to reproductive age

M = average number of offspring per survivor

• big bang

  • body size and reproductive output exponential

iteroparous

individuals reproduce more than once

• calculate a life table

senescence

late life decline in fertility and probability of survival

mutation accumulation hypothesis

late acting deleterious mutations are weakly selected

Late acting muations have _____ effect on lifetime reproductive success

small

inbreeding depression should

increase with age

antagonistic pleiotropy hypothesis

mutations conferring fitness benefits early in life but fitness cost late in life can be advantageous overall

• more individuals experience early benefit than suffer late cost

Natural selection may favor early reproduction where

mortality rates from extrinsic facters (e.g. predators) is high

lack’s hypothesis

selection will favor the clutch size that produces the most surviving offspring

What does lack’s hypothesis predict about clutch size survival?

Intermediate is best

Do bird clutches match lack’s hypothesis?

No, typically smaller clutch

What assumption in lack’s hypothesis is broken?

No trade off between reproductive effort in one year and probability of survival and reproductive success in future years

Optimal clutch size in one year may be ____ than most productive lifetime clutch size

lower

When a mother had a larger clutch to raise, the daughters had

lower reproductive output