Lect 12 Eco

Ecological footprint approach

•carrying capacity depends on amount of resources used by each person.

Ecological footprint

Total area of productive ecosystem required to support a population.

Population Size Equation

N(t+1) = N(t) + B - D + I - E

Geometric growth

•organisms reproduce in synchrony at discrete time periods.

Exponential Growth

organisms reproduce continuously over time. Pop size changes by a constant proportion.

Exponential growth equation

dN / dt = rN

Doubling time

Amount of time it will take a population to double in size

Doubling time Equation

t(d) = ln(2)/r

Density Dependent Factors Example

Resources

Population Regulation

•Density-dependent factors cause population to increase when density is low and decrease when density is high.

Life Table

•Summary of how survival and reproductive rates vary with age, size, or life stage of individuals.

What are life tables used for

to predict future population trends and develop strategies for managing populations.

Static life table

shows survival and reproduction of individuals of different ages during a single time period.

Cohort Life table

•follows the fate of a group of individuals all born at the same time (a cohort).

Age Class

•Members of a population whose ages fall within a specified range.

Age Structure

Proportion of a population in each age class; influences whether population will increase or decrease in size.

Type I Survivorship

Most individuals survive to old age.

Type II Survivorship

•Chance of surviving remains constant throughout the lifetime.

Type III Survivorship

•High death rates for young; those that reach adulthood survive well.

Net Reproductive Rate

• Increases if > 1

• Decreases if < 1

• Remains the same if R = 1

Generation Time

The average age of parents of all offspring produced by the cohort