AP Bio Unit 8 Vocab

Population ecology

The study of factors that cause populations to increase or decrease

Community ecology

The study of how interactions between species affect community structure and organization

Ecosystem ecology

The study of energy flow and the cycling of chemicals among the various biotic and abiotic components in an ecosystem.

Biotic factor

Any living part of the environment with which an organism might interact

Abiotic factor

Physical, or nonliving, factor that shapes an ecosystem

Population

A group of individuals that belong to the same species and live in the same area

Community

All the different populations that live together in an area

Ecosystem

A system formed by the interaction of a community of organisms with their physical environment

Biome

A group of ecosystems that share similar climates and typical organisms

Biosphere

Part of Earth in which life exists including land, water, and air or atmosphere

Habitat

The natural home or environment of an animal, plant, or other organism.

Niche

An organism's particular role in an ecosystem, or how it makes its living.

competitive exclusion principle

Ecological rule that states that no two species can occupy the same exact niche in the same habitat at the same time

Resource partitioning

The division of environmental resources by coexisting species such that the niche of each species differs by one or more significant factors from the niches of all coexisting species

Biodiversity

The variety of life in the world or in a particular habitat or ecosystem.

Population density

The number of individuals in an area of a specific size

Population distribution

A description of how individuals are distributed with respect to one another

Clumped distribution

The most common type of population distribution where many members of the population live close together

Random distribution

Distribution in which the location of members in a population is totally random, location of each individual is determined by chance

Uniform distribution

Distribution where populations are spaced evenly

Exponential growth

Population growth that is unhindered because of the abundance of resources for an ever-increasing population.

Logistic growth

Growth pattern in which a population's growth rate slows or stops following a period of exponential growth

Limiting factor

Any biotic or abiotic factor that restricts the existence, numbers, reproduction, or distribution of organisms

Density dependent factors

Factor that limits a population more as population density increases

Density independent factors

Limiting factor that affects all populations in similar ways, regardless of population size

Biotic potential

The maximum rate at which a population could increase under ideal conditions

Carrying capacity

Largest number of individuals of a population that a environment can support

Survivorship

The percentage of members of a group that are likely to survive to any given age

Type 1 survivorship curve

A pattern of survival over time in which there is high survival throughout most of the life span, but then individuals start to die in large numbers as they approach old age

Type 2 survivorship curve

Fairly constant death rate at all ages

Type 3 survivorship curve

A pattern of survival over time in which there is low survivorship early in life with few individuals reaching adulthood

R-selected species

Species that reproduce early in their life span and produce large numbers of usually small and short-lived offspring in a short period.

K-selected species

Species that produce a few, often fairly large offspring but invest a great deal of time and energy to ensure that most of those offspring reach reproductive age

Species richness

The number of different species in a community

Species diversity

The number and relative abundance of species in a biological community

Simpson's Diversity Index

A measure of diversity between similar ecosystems

Keystone species

A species on which other species in an ecosystem largely depend, such that if it were removed the ecosystem would change drastically

Competition

The struggle between organisms to survive in a habitat with limited resources

Intraspecific competition

Competition among members of the same species

Interspecific competition

Competition between members of different species

Predation

An interaction in which one organism kills another for food

Symbiosis

A close relationship between two species that benefits at least one of the species

Mutalism

Symbiotic relationship in which both species benefit from the relationship

Obligate symbionts

A symbiotic relationship between two organisms in which neither by themselves can exist without the other

Commensalism

A relationship between two organisms in which one organism benefits and the other is unaffected

Parasitism

A relationship between two organisms of different species where one benefits and the other is harmed

Host

An animal or plant that nourishes and supports a parasite

Invasive species

Species that enter new ecosystems and multiply, harming native species and their habitats

Ecological succession

Series of gradual changes that occur in a community following a disturbance

Pioneer species

First species to populate an area during primary succession

Climax community

A stable, mature community that undergoes little or no change in species over time

Primary succession

An ecological succession that begins in an area where no biotic community previously existed

Secondary succession

Succession following a disturbance that destroys a community without destroying the soil

Autotroph/producer

An organism that makes its own food

Primary consumer

An organism that eats producers

Photoautotrophs

Organisms that use light as a source of energy to synthesize organic substances

Chemoautotrophs

Organisms that use hydrogen sulfide or other chemicals as energy source instead of light

Heterotroph/consumer

Organisms that must eat other organisms for energy

Decomposers

Organisms that break down wastes and dead organisms and return raw materials to the environment

Herbivores

Consumers that eat only plants

Carnivores

Consumers that eat only animals

Omnivores

Consumers that eat both plants and animals

Scavengers

Animals that consume the carcasses of other animals that have been killed by predators or have died of other causes

Food chain

A series of steps in which organisms transfer energy by eating and being eaten

Food web

A community of organisms where there are several interrelated food chains

Trophic level

Each step in a food chain or food web

Trophic cascade

Powerful indirect interactions that can control entire ecosystems

Carbon cycle

The organic circulation of carbon from the atmosphere into organisms and back again

Phosphorus cycle

The movement of phosphorus atoms from rocks through the biosphere and hydrosphere and back to rocks

Nitrogen cycle

The transfer of nitrogen from the atmosphere to the soil, to living organisms, and back to the atmosphere

Eutrophication

Excessive richness of nutrients in a lake or other body of water, frequently due to runoff from the land, which causes a dense growth of plant life and death of animal life from lack of oxygen

Greenhouse effect

Natural situation in which heat is retained in Earth's atmosphere by carbon dioxide, methane, water vapor, and other gases