BIOL 117 CH 41 - Ecological Communities

ecological community

all species living in the same place

community

an assemblage of populations of various species living close enough for potential interaction

interspecific interactions

interactions between different species (ex: competition, predation, herbivory, symbiosis)

intraspecific interactions

interactions between same species

competition (-/-)

species compete for a limiting resource

competitive exclusion principle

2 species that fill the exact same ecological niche cannot co-exist in the same ecosystem

fundamental niche

the niche potentially occupied by that species

realized niche

the niche actually occupied by that species

resource paritioning

ecologically similar species can coexist if their niches are different

niche

the “job” a species has within its community

predation (+/-)

one species (predator) kills and eats the other (prey)

cryptic coloration

a pattern of colors that makes an animal hard to see

aposematic coloration

warning colors

Bayesian mimicry

harmless species mimics a harmful one

mullerian mimicry

bunch of unrelated toxic organisms evolve the same coloration and share a mutual benefit

herbivory (+/-)

one species (herbivore) eats the other (plant or algae)

symbiosis

a relationship where greater than or equal to 2 species live in direct and intimate contact (parasitism, mutualism, commensalism)

Parasitism (+/-)

a parasite derives nourishment from a host, which is harmed in the process

endoparasites

live within the body of the host

ectoparasites

live on the external surface of the host

Mutualism (+/+)

interspecific interaction that benefits both species

Commensalism (+/0)

one species benefits and the other is neither harmed or helped

species diversity

is the variety of organisms that make up the community

species richness

the number of different species in the community

relative abundance

the proportion each species represents of all individuals in the community

trophic structure

the feeding relationships between organisms in a community

food chains

link trophic levels from producers to top carnivores

food webs

branching food chains with complex trophic interactions

dominant species

those that are most abundant or have the highest biomass

keystone species

exert strong control on a community by their ecological roles, or niches

equilibrium models

assume that communities follow changes that lead to stable states

disturbance

an event that changes a community, removes organisms from it, and alters resource availability

high level of disturbance

result of a high intensity and high frequency of disturbance

low disturbance level

result of either low intensity or low frequency of disturbance

intermediate disturbance hypothesis

moderate levels of disturbance can foster greater diversity

ecological succession

the sequence of community and ecosystem changes after a disturbance

primary succession

occurs where no soil exists when succession begins

secondary succession

begins in an area where soil remains after a disturbance