Life Historuy

Life History

Schedule of key events in an organism's life cycle relating to its survival, growth, and reproduction

What does life history cover

1. # of offspring produced

2. survival

3. size

4. age of maturity

Principle of Allocation

Organisms must make a trade-off because they have a finite amount of resources to use for all necessary life processes

Fish size and fecundity in fish

Larger females produce more eggs, but produce fewer eggs, lowering gene flow

Recruitment

Ability to add individuals somewhere for population

Unassisted dispersal

No special structures (wind)

Adhesion dispersal

Hooks or barbs to hang from animals

Wind dispersal

Wings or hairs for travel

Animals dispersal

Ant, vertebrae, etc directly take seeds that could be digested or buried elsewhere

How does seed size relate to performance

Larger seeds have more energy to make larger seedings that boost growth and recruitment

How does energy allocation differ before vs. after sexual maturity?

Before: growth + maintenance. After: growth + maintenance + reproduction

What is the relationship between adult survival and age at maturity?

• High adult survival → late maturity, reproduce multiple times once grown type 1 or 2

• Low adult survival → early maturity, reproduce early type 3

R-selected species

Organisms that reproduce in large numbers, mature quickly, and invest little energy in raising their offspring

K-selected

Organisms that reproduce less, mature later, and invest more time into raising offspring

Selective Pressures in plants

1. Low disturbance, low stress

2. Low disturbance, high stress

3. High disturbance, low stress

4. High disturbance, high stress

Ruderals

When in very disturbed environments, plants grow quickly, produce seeds in large numbers, r-selected

Stress tolerant

High stress, no disturbance environments, plants grow slower, similar to k-select

Competitive

Low disturbance, low stress,fast growth, tall, large leaves, competitive

Opportunistic

Ecological strategy to reproduce rapidly in disturbed environments (like r-selected or ruderal) (insects, annual plants)

Equilibrium

Strategy to focus on survival, slow growth, delayed reproduction to provide a competitive advantage (humans, elephants)

Periodic

Long-lived organisms produce massive numbers of small offspring during predictable, seasonal (salmon)