Competition Test 3

Competition (−/−)

Interaction in which both participants incur a cost occurs when individuals experience limited resources.

Commensalism (+/0)

One species benefits while the other is not significantly affected.

Consumption (+/−)

One organism benefits by consuming another organism or its tissues.

Mutualism (+/+)

Both interacting species gain fitness benefits.

Intraspecific competition

Competition among individuals of the same species; often density-dependent.

Interspecific competition

Competition between individuals of different species.

Competition and natural selection

Competition is a driving force of natural selection Because competition has costs for both species, there is strong natural selection on both species to avoid the same niche

Evolutionary arms race in competition

Repeated adaptations by competitors to outcompete one another.

Competitive exclusion principle

Two species with identical niches cannot coexist in that niche indefinitely.

Resource partitioning or niche differentiation

Evolutionary differentiation in resource use that reduces competition.

Resource segregation

Species divide shared resources, can be used to understand where similar species are different Can see where competition of their niche spaces was the greatest

Fundamental niche

Physical conditions which a species might live in with the absence of interactions with other species

Realized niche

Actual niche restricted by interactions such as competition.

Image: MacArthur’s warblers

Warbler species use different portions of trees, illustrating resource partitioning.

Image: competition drives niche partitioning

Species differ in resource use when competition shapes their realized niches.

Image: intraspecific vs. interspecific competition

Within-species competition contrasts with competition between different species.

Competition: why does niche partitioning help coexistence?

Species use different resources or areas, reducing costly overlap and competition.

Image: MacArthur warbler tree zones

Different warbler species forage in different parts of conifer trees, reducing niche overlap.

Fundamental vs. realized niche

Fundamental is the potential niche without species interactions; realized is the niche actually occupied.