11_Competition_BI370

Exploitative competition

One species consumes resources needed by another without direct contact.

Interference competition

One species blocks access to a resource another needs, generally requiring direct contact.

Competitive exclusion principle

Two species strongly competing for the same limited resource cannot coexist indefinitely.

Resource partitioning

The division of resources among species to allow coexistence; each species specializes on one element of the resource.

Ecological character displacement

Change in species characteristics to more efficiently exploit a resource, allowing for resource partitioning.

Zero growth isocline species 1

N1 = K1 - (αN2)

Competition coefficients (α and β)

Converts resources per individual from the competing species to the relative equivalent of individuals in the original species.

Niche overlap

Competition results from overlapping niches

Asymmetric competition

Competition varies in intensity and symmetry, from amensalism to equal impact on both species.

Disturbances

can prevent the full course of competition from playing out

Competitive dominance

If isoclines do not cross, the top species wins.

Dominance depends on starting conditions

Isoclines cross with k’s on the outside; strong interspecific competition

Stable coexistence

Isoclines cross with k’s on the inside; strong intraspecific competition

Predators, parasites, and herbivores

Target the most densely populated species

Physical environment

Can modify competitive outcomes if the competitively superior species is put in an environment where it does not operate well

Species 2 competition model

dN2/dt = r2N2((K2-N2-βN1)/K2)

Species 1 competition model

dN1/dt = r1N1((K1-N1-αN2)/K1)

Species 2 zero growth isocline

N2 = K2 - βN1

Species 1 x-intercept

K1

Species 1 y-intercept

K1/α

Species 2 x-intercept

K2/β

Species 2 y-intercept

K2