ecology slide deck 5 (population ecology part 1)

population

a group of individuals of the same species that inhabit a given area

populations have structure including

density, spacing, and age distribution

the distribution of a population is

the area over which it occurs

the geographic range of a species encompasses

all of the individuals of a species

examples of geographic barriers

bodies of water, mountains, large areas of unsuitable habitats

metapopulations

collection of local subpopulations linked through dispersal or other means of genetic exchange

abundance

number of individuals in population

density

area over which population is distributed

there are three distribution patterns that are seen in organisms

random, uniform, and clumped

random

spaced unpredictably

uniform

evenly spaced

clumped

grouped in patches

population size (abundance) =

populations density x the area occupied

absolute density (25 gopher tortoises/hectare)

complete count of individuals/area

relative density (25% sunflowers/m2)

proportion of species relative to others in a community

quadrat sampling

sample area of a given shape

transects

sample along a line or path

mark-recapture

capture, mark, release, recapture

lincoln-petersen method

N=nM/R

N=

number of animals in the population

M=

number of animals marked on the first visit

n=

number of animals captures on the second visit

R=

number of recaptured animals that were marked

lincoln-petersen assumptions

sampling is random for marked and unmarked individuals, mark doesn't cause injury with adverse effects to individuals, mark doesn't make it easier for predators to locate marked individuals, marks are not lost, marked and unmarked have same mortality

traps

live animal traps, light traps, pitfall traps, plankton nets