Ch. 45 The Niche

Niche

the role a species plays in a community

• originally meant the sum of the habitat requirements needed for a species’ survival and reproduction

Fundamental niche

the full range of climate conditions and food resources that permit the individuals in a species to live (ideal)

Realized niche

the actual range of habitats occupied by a species

Phylogenetic niche conservatism

closely related species tend to be more similar to each other in niches than are distantly related species

Antagonisms

interactions in which at least one participant loses more than it gains

Competition

an interaction in which the use of a mutually needed resource by one individual or group of individuals reduces the availability of that resource to another individual or group

Interspecific competition

competition among individuals of different species

Intraspecific competition

competition among individuals of a single species

Competitive exclusion

the idea that two species cannot occupy the same exact niche at the same time

Resource partitioning

a process in which species whose niches overlap diverge over time with the result that the overlap is minimized

• allows two or more species to coexist in particular places

Predation

one organism (a predator) consumes another (its prey)

• predator benefits at the expense of the prey

Parasitism

one participant benefits at the expense of another

• live in close association with another species

• gaining nutrition by consuming their hosts’ tissues

• reduce host fitness and ability to reproduce/increase susceptibility to environmental conditions by tapping its resources

Herbivory

the consumption of plant parts, benefits herbivorous animals by providing nutrients

• harms plants by affecting products of photosynthesis

Mutualism

when benefits for each participant outweigh their costs

Symbioses

close interactions between species, either antagonisms or mutualisms that have evolved over long periods of time

Obligate

when one of both sides of a mutualism cannot survive without the other

Facultative

one or both participants can survive without the other

Commensalisms

one partner benefits, and there is no apparent effect on the other

• e.g. barnacles

Facilitation

one species creates an environment that helps another

• can include both mutualisms and commensalisms

Community

the set of all populations of two or more different species found in a given place at a particular time

Biodiversity

the total # of species, or the diversity of genetic sequences, cell types, metabolisms, life histories, phylogenetic groups, communities, and ecosystems

Keystone species

• populations that affect other members of the community in ways that are disproportionate to their abundance or biomass

• pivotal populations

• they support a community in much the same way that an architectural keystone supports an arch

Succession

species replacing each other in time in a predictable sequence

Climax community

one in which there is little further change in species composition

Theory of island biogeography

the number of species that can occupy an island depends on the size of the island and the distance of the island from a source of colonists

Species-area relationship

a mathematical relationship between the number of species and the size of an island