life history theory

life history

age-specific schedule of reproduction and mortality of a population of individuals

What does a trade-off in life history mean?

Resources used for one trait can't be used for another—e.g., survival vs. reproduction.

What is reproductive value?

Expected future reproduction of an individual at a given age.

How does reproductive value change over life?

Usually low in youth, rises with maturity, then falls with age.

What clutch/litter size does natural selection favor?

The size that maximizes the number of surviving offspring.

What is Lack’s hypothesis?

There’s an optimal brood size that maximizes parental LRS.

What is semelparity?

A “big bang” strategy: breed once, then die.

When is semelparity favored?

High juvenile survival & low adult survival.

What is iteroparity?

Repeated reproduction over a lifetime.

When is iteroparity favored?

Low juvenile survival & high adult survival.

What are hypotheses for menopause evolution?

Mother, grandmother, and reproductive conflict hypotheses.

Do Darwinian demons exist?

No—because trade-offs prevent maxing out all traits.

When is early reproduction usually favored?

In r-selected species and expanding populations.

What is the downside of early reproduction?

Often trades quality for quantity.