Ecology Vocab Quiz (copy)

age structure 

Distribution of population members among various age categories.

area effect

Larger islands receive more immigrants and have a lower extinction rate than small ones.

biomass pyramid

For an ecosystem, a graphic depicting the mass of organic material in the bodies of organisms at each trophic level at a specific time

biosphere

All regions of Earth where organisms live.

biotic potential

Maximum possible population growth rate under optimal conditions.

brood parasitism

One egg-laying species benefits by having another raise its offspring.

carrying capacity (*K*)

Maximum number of individuals of a species that a particular environment can sustain; can change over time.

character displacement

As a result of competition, two species become less similar in their resource requirements.

commensalism

Species interaction that benefits one species and neither helps nor harms the other.

community

All populations of all species in a defined area.

competitive exclusion

Process whereby two species compete for a limiting resource, and one drives the other to local extinction.

consumer

Organism that gets energy and nutrients by feeding on tissues, wastes, or remains of other organisms.

decomposer

Heterotroph that feeds on organic remains by breaking them down into smaller, absorbable subunits.

density-dependent limiting factor

Factor that limits population growth and has a greater effect in denser populations; for example, competition for a limited resource

density-independent limiting factor

Factor that limits population growth and arises regardless of population size; for example, a flood.

detritivore

Animal that feeds on small bits of organic material.

distance effect

Islands close to a mainland receive more immigrants than those farther away

ecological footprint

Area of Earth’s surface required to sustainably support a particular level of development and consumption.

ecological niche

Of a species, unique set of requirements and roles in an ecosystem.

ecology

The study of interactions between organisms and their environments.

ecosystem

A biological community interacting with its environment.

emigration

Movement of individuals out of a population.

endemic species

A species found only in the region where it evolved.

energy pyramid

For an ecosystem, a graphic depicting the energy that flows through each trophic level in a given interval.

exotic species

A species that evolved in one community and later became established in a different one.

exponential growth

A population grows by a fixed percentage in successive time intervals; the size of each increase is determined by the current population size.

food chain

Description of who eats whom in one path of energy flow through an ecosystem.

food web

Set of cross-connecting food chains.

habitat

Type of environment in which a species typically lives.

immigration

Movement of individuals into a population.

indicator species

Species whose presence and abundance in a community provide information about conditions in the community.

interspecific competition

Competition between members of different species.

intraspecific competition

Competition for resources among members of the same species.

island biogeography

field that examines the factors that affect the species richness of isolated natural communities, specifically on oceanic islands

keystone species

A species that has a disproportionately large effect on community structure relative to its abundance.

*K*-selection

Pattern of selection in which adaptive traits allow their bearers to outcompete others for limited resources; occurs when a population is near its environment’s carrying capacity

logistic growth

A population grows exponentially at first, then growth slows as population size approaches the environment’s carrying capacity for that species.

mutualism

Species interaction that benefits both species.

parasitism

Relationship in which one species withdraws nutrients from another species, without immediately killing it.

parasitoid

An insect that lays eggs in another insect, and whose young devour their host from the inside.

per capita growth rate (*r*)

Of a population, per capita (per individual) birth rate minus per capita death rate.

pioneer species

Species that can colonize a new habitat.

population density

Number of individuals per unit area.

population distribution

Location of population members relative to one another: clumped, uniformly dispersed, or randomly dispersed.

population size

Total number of individuals in a population.

primary production

The rate at which an ecosystem’s producers capture and store energy.

primary succession

A new community becomes established in an area where there was previously no soil.

producer

Autotroph. Organism that makes its own food using energy and nonbiological raw materials from the environment.

replacement fertility rate

Number of children a woman must bear to replace herself with one daughter of reproductive age.

reproductive base

Of a population, members of the reproductive and pre-reproductive age categories.

resource partitioning

Evolutionary process whereby species become adapted in different ways to access different portions of a limited resource; allows species with similar needs to coexist.

*r*-selection

Pattern of natural selection in which producing the most offspring the most quickly is adaptive; occurs when population density is low and resources are abundant.

secondary succession

A new community becomes established in a site where a community previously existed.

species evenness

Of a community, the relative abundance of species.

species richness

Of a community, the number of species.

survivorship curve

Graph showing how many members of a cohort remain alive over time.

symbiosis

One species lives in or on another in a commensal, mutualistic, or parasitic relationship.

total fertility rate

Expected number of children a woman will bear over the course of a lifetime.

trophic level

Position of an organism in a food chain.

zero population growth

Interval during which the number of births equals the number of deaths.