1. 53.4-53.5 Population Ecology

2. Life History Natural selection produces some traits that favor a population’s ability to survive and reproduce Variables include: 1. When reproduction begins (age at first reproduction or age at maturity) 2. How often an organism reproduces 3. How many offspring are produced per reproductive episode Organisms do not consciously choose when or how many offspring to have Except humans… more on that in 53.6

3. Life History K-selection Density-dependent Favored at high density areas where populations are at or near carrying capacity (K) and face a lot of competition Have late reproduction, few offspring, parents invest in raising offspring Ex: primates, elephants

4. Life History R-selection Density-independent Favored in low density areas Maximizes r (per capita rate of increase) in areas well below carrying capacity with little competition Have early reproduction, many offspring, little parental care Ex: insects, many plants

6. Limiting Factors Environmental factors prevent exponential growth

7. Population Limitations Density Dependent Factors Limitations due to the size of population Death rate rises as population density rises Density Independent Factors Limitations with no relationship to population size Birth or death rate does not change with population density

8. Density Dependent Competition Territoriality Predation Disease Toxic waste Intrinsic factors

9. Density Independent Natural Disasters Tornado, Hurricane, Fire, Volcano, etc.

10. Population Dynamics Populations of different species tend to cycle with each other Example: hare and lynx