Environmental Science Population Ecology Terms

population

group of individuals/organisms of the same species living in a particular area

community

populations of all species living and interacting in an area at a particular time

Niche

total way of life or role of species in an ecosystem. It includes all physical, chemical, and biological conditions that a species needs to live and produce in an ecosystem.

Habitat

place or type of place where an organism or population of organisms live

competition

two or more individual organisms of a single species or two or more individuals of different species attempting to use the same scarce resources in the same ecosystem

interspecific competition

attempts by members of two or more species to use the same limited resources in an ecosystem

intraspecific competition

attempts by two or more organisms of a single species to use the same limited resources in an ecosystem.

competitive exclusion/Gause's Principle

two species that compete for the exact same resource cannot stably coexist.

Realized Niche

parts of the fundamental niche of a species that are actually used by that species

fundamental niche

full potential range of the physical, chemical, and biological factors a species can use if it does not face any competition from other species

predation

situation in which an organism of one species captures and feeds on all or part of an organism of a different species

symbiotic relationship

relationship between two entities which is mutually beneficial for the participants of the relationship

mutualism

type of species interaction in which both participating species generally benefit

commensalism

interaction between organisms of different species in which one type of organism benefits and the other type is neither helped nor harmed to any great degree

parasitism

interaction between species in which one organism, called the parasite, preys on another organism, called the host, by living on or in the host

biotic balance

an ideal condition in which the interrelationships of organisms to one another and their environment appear harmonious, like a climax forest.

keystone species

species that play roles affecting many other organisms in an ecosystem

indicator species

species that serve as early warnings that a community or ecosystem is being degraded

indigenous species

species native to a given region or ecosystem if its presence in that region is the result of only natural processes, with no human intervention

invasive species

species that migrate into an ecosystem or are deliberately or accidentally introduced into an ecosystem by humans

ecological succession

process in which communities of plant and animal species in a particular area are replaced over time by a series of different and often more complex communities

primary succession

ecological succession in a bare area that has never been occupied by a community of organisms

secondary succession

ecological succession in an area in which natural vegetation has been removed or destroyed but the soil is not destroyed

pioneer species

first hardy species often microbes, mosses, and lichens, that begin colonizing a site as the first state of ecological succession

Climax community

fairly stable, self-sustaining community in an advanced stage of ecological succession; usually has a diverse array of species and ecological niches; captures and uses energy and cycles critical chemicals more efficiently than simpler, immature communitie

habitat fragmentation

breakup of a habitat into smaller pieces, usually as a result of human activities

ecotones

a region of transition between two biological communities

ecozones

ecorealm, biogeographic realm or simply biorealm is the largest scale biogeographic division of Earth's land and is characterized by interactive and adjusting abiotic and biotic factors

edge effect

placing side by side of contrasting environments on an ecosystem

theory of island biogeography

a field within biogeography attempting to explain what factors affect the species richness of natural communities

law of tolerance

the amount of an item that can be present before a permanent helpful/harmful effect will take place

law of minimum

growth is controlled not by the total amount of resources available, but by the scarcest resource or limiting factor

population density

number of organisms in a particular population found in a specified area or volume.

population dispersion

general pattern in which the members of a population are arranged throughout its habitat

r selected organisms

have a high growth rate, suitable in an unstable environment, short lives, and have many offspring

k selected organisms

populations or roughly constant size, low productive rates, limited and competitive in resources

disease, hunting, natural factors

3 population limiting factors

education, cultural influence, government policies

3 factors affecting fertility rates

replacement birth rate

total fertility rate at which women would have only enough children to replace themselves and their partner

better medical attention, new technology, better hygiene

3 reasons people live longer