Notes

ch 45 species interactions & communities

niche - the physical habitat & ecological role of a species; determined by both abiotic & biotic factors; reflect both where organisms occur & what they do there; also refers to the ways organisms respond to & affect the resource & other species in the habitat

fundamental niche - the full range of climate conditions & food resources that permit the individuals in a species to live

realized niche - the actual range of habitats occupied by a species; interactions with other species reduce the range through competition or predation

phylogenetic niche conservatism - closely related species tend to be more similar to each other in niches

species interactions: all interactions combine costs & benefits
antagonistic - ones species loses more than it benefits or is harmed (competition, predation, parasitism, herbivory)
mutualistic - both species benefit
commensalism - one species benefits /w no apparent effect on other species

antagonistic interactions:

competition - individuals use the same limited resource
intraspecific competition - competition btwn individuals of a single species
interspecific competition - competition btwn individuals of different species
competitive exclusion - 2 species have overlapping niches so one will either become extinct or move form their fundamental niche to a realized niche
resource partitioning - species whose niches overlap diverge & become different species or subspecies due to different habitat use & feeding strategies; overlap btwn closely related groups is minimized

predation - one organism (predator) consumes another (prey); predators limit prey population
huffaker predator-prey experiment: predatory-prey systems can be stable if prey can temporarily escape predators

parasitism - parasites live in close association /w another species & consume the host's tissues; parasites reduce host's fitness & limit population size

herbivory - consumption of plant parts directly affects the products of photosynthesis & plant productivity; herbivores benefit while plants are harmed

mutualistic interactions:

symbioses - close interactions btwn species that have evolved over long periods of time; coevolution
obligate - 1 or both sides cannot survive w/o the other
facultative - 1 or both sides can survive w/o the other

commensalism:
facilitation - indirect interaction where one species creates a suitable habitat for another

community - set of all populations in a given place
biodiversity - genetic sequences, cell types, species, life histories, phylogenetic groups, communities, ecosystems

keystone species - a species that affects other species in ways disproportionate to its abundance or biomass; the community depends strongly on the species

succession - a predictable sequence of species that colonize & then transform the community following a physical disturbance
climax community - a mature assembly formed in the final stage of succession

theory of island biogeogapahy - the # of species that can occupy a habitat island depends on 2 factors: the island sie & its distance from colonists

species-area relationship - relationship btwn island size & # of species; S = cA^x
S = # of species at equilibrium
c = mathematical constant
A = habitat area
x = experimentally determiend exponent relating species # to habitat area