CH45: Community Ecology

community ecology

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the study of the interactions between species in a particular geographic area or habitat. It focuses on understanding the patterns and processes that shape the structure and dynamics of ecological communities, including the relationships between species, their physical environment, and their biotic interactions.

community

all species that live in a particular region

habitat

specific environment in which a species live

richness

the number of species

species evenness

relative abundance of each species

indirect interactions

a situation such as birds eating caterpillars which benefits the trees on which the caterpillars feed

direct interactions

have an effect on both participants.

commensalism

one species benefits from an interaction and the other is unaffected

symbiosis

“living together” two species with a prolonged close association that benefits at least one of them.

mutualism

interspecific interaction that benefits both participants

obligate mutualism

coevolution of two species that results in a mutual dependence

interspecific competition

competition between two species

ecological niche

type of resources and environmental conditions/interactions required by an organism

interference competition

one species actively prevents another from accessing some resource

exploitative competition

competing species do not interact directly. each species reduces the amount of resource available to the other species by using the resource.

competitive exclusion

whenever two species require the same resources to live or reproduce, the better competitor will drive the other to extinction in that habitat

resource partitioning

an evolutionary process in which species adapt to use a shared limited resource in a way that minimizes competition

character displacement

range of variation for one or more traits is shifted in a direction that lessens competition for a limited resource

predation

interspecific interaction in which one species captures, kills, and eats the other

warning coloration

a conspicuous color pattern well-defended prey have that predators learn to avoid

mimicry

a species evolves traits that make it similar in appearance to other species

mullerian mimicry

tendency of well-defended species to have the same coloration i.e stinging wasps and bees

batesian mimicry

a species that lacks a defense mimics the appearance of a well-defended species

camouflage

body shape, color pattern, or behavior that allows an individual to blend into its surroundings

herbivory

animal feeds on plants

parasitism

parasite benefits by feeding on the host without killing it immediately

brood parasitism

one species benefits by another raising its offspring

parasitoids

insects that lay their eggs in the body of other insects

biological pest control

practice of using a pest’s natural enemies to control its numbers

pioneer species

first to arrive in new or newly vacated habitats; species that colonize a new habitat. often mosses and lichens

primary succession

the process that begins when pioneer species colonize a barren habitat with no soil, such as a new volcanic island or land exposed by the retreat of a glacier.

secondary succession

a new community develops in a disturbed site where the soil that supported a previous community remains.

intermediate disturbance hypothesis

species richness is greatest when physical and biological disturbances are moderate in intensity or frequency

indicator species

species that are especially sensitive to environmental changes i.e. trout in a stream, frogs, lichen

keystone species

has a disproportionately large effect on a community relative to its abundance

exotic species

resident of an established community that became resident elsewhere

endemic species

a species found in the region where it evolved and nowhere else

biogeography

study of how species are distributed in the natural world

equilibrium model of island biogeography

developed by Robert H. MacArthur and Edward O. Wilson. describes a balance between immigration rates of new species and extinction rates of established species

distance effect

islands close to a mainland have more species than those farther away

area effect

larger islands have more species than small ones