Ecology Chapter 12: Population Distribution; Final Information

Mark and recapture

Technique in which individuals are marked and recaptured to estimate population density

N = Mn/M

Mark and recapture equation for determining population size

N

Number in the population

M

Number of individuals marked and released in the first event

n

Number recaptured in the second event

m

Number of marked individuals in the second event

Assumptions in mark and recapture

That marked and unmarked individuals are caught randomly, that individuals are equally trappable, that no births or deaths occur between samples, and that marks are not lost or overlooked

Quantifying dispersal

System for tracking dispersal that can indicate a geographic range that is expanding rapidly if a few individuals can disperse much farther than the average individuals

Population abundance and range

Reduction in the range of a population indicates a reduction in the size of the population; populations with high abundance have large geographic ranges

Population density and body size

Density of a population is negatively correlated to the body size of individuals in the population

Dispersal limitation

Absence of a population from a suitable habitat due to dispersal barriers

Dispersal barriers

Large expanses of inhospitable habitat, often caused by human infrastructure

Habitat corridor

Strip of favorable habitat located between two large patches of habitat that facilitate dispersal

The ideal free distribution (IFD)

The idea that, with two habitats of differing abundance, each individual should chose a habitat to maximize payoff

Ideal free distribution assumptions

No territoriality, that all competitors experience equal benefits, that the average gain rates are equal in all patches, and that the number of individuals in a patch should be directly proportional to the resource input rate