Populations

## s-curve------------------------------------j- (exponential) curve

### Reproductive Strategies:

A) r-strategies: Reproductive strategy where the population puts more resources into producing as many offspring as possible in a short period of time. This reproductive strategy is common in unstable or rapidly changing environments. Examples: salmon (those that reproduce only once), protozoa, bacteria. Characteristics of this strategy include:

a) short life span

b) early maturity (they are capable of reproducing very quickly)

c) small body size

d) reproduce only once

e) many offspring produced per reproductive cycle.

B) k-strategies: Reproductive strategy where the population puts more resources into development and long-term survival of each individual. This reproductive strategy is common in stable, unchanging environments. Examples: whales, sharks, humans. Characteristics of this strategy include:

a) long life span

b) late maturity

c) large body size

d) reproducing many times over long periods of time.

e) one or two offspring per reproductive cycle

### All populations eventually reach equilibrium with their environment. Those with exponential growth tend to overshoot their carrying capacity & crash back to low #s.

Population Studies

Random Sampling: Method to scientifically estimate population of individuals in an area using a grid. Count individuals in some grids, average, and multiply by total # of grids.

Mark-capture method: Capture & mark individuals. Release. Capture more individuals. Note how many marked individuals there are. Use Lincoln Index below.

Lincoln Population Index: A mathematical model for estimating population size when counting the whole population would be too difficult to do.

Population Size = (n1 X n2) / n3

where: n1 = # caught, marked, & released 1st time.

n2 = # captured 2nd time.

n3 = number of marked individuals caught 2nd time.

Slichter