Population Ecology - Bio 1108

population

group of interbreeding individuals occupying the same habitat at the same time

population ecology

studies factors affecting population size and how they change over space and time

population size

represented by N, total number of individuals

population density

the number of individuals within a specific area volume

demography

statistical study of population changes over time (birth, death rates and life expectancies)

life tables

table that divides the population into age groups and often sexes and show how long a member of that group is likely to live

mortality rate

probability of individuals dying before their next birthday

methods for estimating population density

quadrant, pitfall trap, mist net, live mammal trap

quadrant method

square area is marked off and all individuals are counted

• repeated in multiple locations to estimate count for whole area

• size of quadrant varies depending on species being studied

mark-recapture method

individuals are captured, counted, and marked with tag or other system so they are recognized when captured again

• released back into the population

• another group is captured later

  • ratio of marked to unmarked individuals helps estimate the total population size

species dispersion patterns

spatial relationship between members of a population at a particular point in time

• clumped, uniform, random

clumped

• this dispersion pattern is the most common

• resources tend to be clustered in nature

  • social behavior may promote this pattern

uniform

• this spatial distribution pattern has an equal distance between individuals

  • competition may cause this pattern and may result from social interactions

random

this distribution pattern is the rarest

• resources are rarely randomly spaced in nature

• may occur where resources are common and abundant

survivorship curves

show the distribution of individuals in a population according to age

three types: I, II, and III

Type I

this survivorship curve shows death primarily occurring in the older years

Type II

this survivorship curves shows that death at any age is equally probable

Type III

This survivorship curve shows that very few survive the younger years but after a certain age, individuals are much more likely to survive

fecundity

potential reproductive capacity of an individual within a population

• measure of the maximum potential reproductive output

  • depends on factors such as how many offspring are produced at once and how many times a year an organism can reproduce

inversely

How are fecundity and parental care related? (directly or inversely)