APES Ecology Review

ecosystem

a community of living (biotic) organisms interacting with the non-living (abiotic) components of their environment as a system through various nutrients and energy cycles

biotic

living

abiotic

nonliving

species

organisms that resemble each other; are similar in genetic makeup and behavior, and are able to interbreed and produce fertile offspring

biodiversity

variety of different species of living organisms within a particular ecosystem; includes diversity within and between species

population

organisms of the same species that interact with each other and occupy a specific area

community

many different populations living in one area; can be similar or different populations of species

biome

major, regional, or global biotic communities characterized by climate and diversity of organisms

biosphere

consists of all life on Earth and all parts of the Earth in which life exists; inclusive of land, water, and atmosphere

autotroph/producer

an organism that uses energy from the Sun to produce usable forms of energy

heterotroph/consumer

organisms that use other organisms as a source of food energy and body building materials

trophic level

the position of an organism in a food web/chain

scavenger

organism that feeds on dead organisms

decomposer

an organism that breaks down dead organisms/organic material; typically fungi, insects, earthworms, and bacteria

detrivore

organism which feeds on organic (dead) material

biomass

the mass of living biological organisms in a given area or ecosystem; the sum of all living organisms in a given area/trophic level

niche

a particular area within a habitat occupied by an organism, as well as the function of that organism within it ecological community

habitat

the natural home/environment of an organism

competition

when two or more organisms compete for the same resources including water, prey, space, etc.

competitive exclusion principle

no two species can occupy the same niche indefinitely in a habitat where there is not enough of a particular resource to meet the needs of both species; essentially, one species will eventually prevail over the other

resource partitioning

the division of limited resources by species in an attempt to avoid competition in an ecological niche

limiting factor

any abiotic (non-living factor) that limits or prevents the growth of a population

exponential growth

starts slowly but then accelerates as the population increases because the base size of the population is increasing; depicted by a J-curve

logistic growth

when exponential growth has to stop; depicted by an S-curve; due to carrying capacity of the environment (not enough resources to keep growing in population size)

carrying capacity

the maximum population of a given species that a particular habitat can sustain indefinitely