Chapter 13- interspecific competition

Alpha

competition coefficient that shows impact of species 2 on 1

Beta

Impact of species 1 on 2

Reduction in pop size due to competition

multiply competition coefficient by population size (beta * N2) to get this

Population zero growth isoclines

showing the combination of species densities where a population’s growth rate is zero

Lotka Volterra model

4 species outcomes for two competing populations by overlapping two graphs of their pops

What are outcomes of lotka Volterra dependent on

alpha, beta, k1, and k2.

Black lines

the isocline for species 1

Below black line

population increases

Above black line

population decreases

Orange line

isocline species 2

If K1 is higher than k2 allowing for larger species 1 population then

species 1 wins the competition

In C the isoclines intersect meaning

stable coexistence

In D the isoclines intersect but not like C

each species intersect each other and competition is unstable

What could cause scenario D

niche overlap, interference competition, limited resources, difference in initial pop size, env disturbance

Gause experiments

pop growth of 1 species in absence of other and both too

Which is better competitor

P. Aurelia

Which lotka Volterra model predicts this

scenario A due to P. aurelia uses resources more efficiently and suppresses P. caudatum more than vice versa

Which species wins the competition of mixed populations

synedra

Which graph shows intraspecific competition

Graph B

Which graph shows interspecific competition

Graph C

If coefficient beta (1 on 2) changes from .5 to .25 how would this influence competition

Species 1 now has a weaker competitive effect on species 2

Why would species 1 be weaker competitively on 2 if beta decreased

k2/beta

Transplantation study

where plants moved from normal range

Which species better adapted to stress of flooding in low marsh

spartina alterniflora

What should 1 species do in the absence of competing species

take advantage of the situation and expand their niche width

Niche width

measures the range of resources used, or environmental conditions tolerated, by a species

Invasive species

when there is absence of competing species they will naturally expand niche width

What does the graph show

niche partitioning for prey across cat species as well as male and females

Adaptation by NS

leads to divergence for niche partitioning

Character displacement

results from niche partitioning in the presence of each other in species