Ecology Chapter 13: Competition

damselfish example

shelter spawning, tend algae; competition for territory; demonstrates resource limitation, interference competion, and resource competition

resource limitation

limitation on population growth due to resource availability

interference competition

direct antagonistic interactions between individuals

examples of interference competition

territoriality, chemical poisoning, and overgrowing

resource (exploitative) competition

does not involve direct antagonistic interactions between individuals

example of resource competition

individual gets to a spot first or eats food first

intraspecific competition

competition among individuals of same species

interspecific competition

competition among individuals of different species

intraspecific competition examples

sorghastrum nutans (indiangrass), creosote bush, M. sativa alfalfa, spartina alternifolia (smooth cordgrass) and prokelisia marginata (planthopper)

sorghastrum nutans (indiangrass)

grew at low vs high density; grew to a large size at low density; biomass increased when density decreased

creosote bush

thin out over timel overlap with other root systems minimal; intraspecific competition resulting in uniform distribution

3/2 self-thinning rule

plotting average weight of individual plants against density produces a 3/2 slope

m. sativa alfalfa

fewer larger individuals with age self-thinning; dry weight increased as density decreased

high population density of planthoppers=

lower survivorship, high developing time, low adult size

lotka-volterra equation

dN1/dt=r1N1(K1-N1-a12N2/K1) AND dN2/dt=r2N2(K2-N2-a21N1/K2)

a12 and a21

competition coefficients express negative competitive effects of individuals of one species on population growth of another species

a 12 is the

effect of species 2 on species 1 relative to the effect of species 1 on species 1

a 21 is the

effect of species 1 on species 2 relative to the effect of species 2 on species 2

value of lotka volterra equations when there is no population growth

N1=K1-a12N2

isoclines of zero population growth

lines that follow population sizes of each species at which that species will exhibit no population growth

when species 1 population equals K-a12

it will not grow or decline it will be stable

logistic growth

only limited by carrying capacity

tribolium castaneum (red flour beetle)

2 species grown in hot/wet and cold/dry

priority effect

species estabilishing itself in greater numbers before competitors win competition

geospiza fortis (medium ground finch)

niche environment, factors that influence its growth, survival, and reproduction

competitive exclusion principle

2 species with identical niches cannot coexist indefinitely

red floud beetle example of

priority effect

geospiza fortis example of

competitive exclusion principle