AP Biology Chapter 8 - Ecology

Population

A group of organisms from the same species that live together

Community

A group of populations of different species in an area

Ecosystem

Community of organisms in an area that interact with each other and the environment

Biosphere

Global ecosystem

Kinesis

Random movement that does not involve stimuli

Taxis

Moving toward or away from a stimulus

Demography

Study of vital statistics of a population and how they change over time

Semelparity

Organisms that reproduce once and die

Iteroparity

Organisms that reproduce repeatedly throughout their life

Carrying Capacity

Maximum population size that the environment can support

Exponential Growth Curve

Population with unlimited resources and continued growth in ideal conditions; leading to a J-shaped graph.,

dN/dT = rmaxN

Logistic Growth Curve

S-shaped graph showing how the population growth tapers off as it gets closer to the carrying capacity

dN/dt = rmax N (K-N)/K

K-selection

Density-dependent selection that selects life history traits that are sensitive to population density

R-selection

Density-independent selection. Selects life history traits that maximizes reproduction

Fundamental Niche

describes the entire range of environmental conditions and resources a species could potentially use to survive and reproduce, assuming no competition or predation

Realized Niche

the actual portion of a fundamental niche that a species occupies and uses in an ecosystem due to the presence of other species, such as competitors, predators, or parasites

Symbiosis

Relationship where two or more species live in direct & intimate contact with one another

Parasitism

Parasitic organism derives nourishment from a host organism

Mutualism

Interspecific interaction that benefits both species. Obligate mutualism: organisms must be together. Facultative mutualism: both species can survive alone.

Commensalism

One species benefits and the other is apparently unaffected

Keystone Species

an organism with a disproportionately large effect on its ecosystem

Invasive Species

a non-native organism that spreads from its original location and causes harm to the environment

Ecological Succession

the gradual process where the species in an ecological community change over time, often following a disturbance or the creation of a new habitat

Primary Succession

slow ecological process where life colonizes an environment that is barren and uninhabited

Secondary Succession

ecological process where life colonizes a previously inhabited but currently disturbed environment

Autotroph (Energy Producers)

Organisms that produce their own food through photosynthesis and chemosynthesis. They form the base of the food chain.

Heterotroph (Primary Consumers)

Organisms that cannot produce their own food and consume other organisms (usually producers) for energy. 

Detrivore (Decomposer)

Consumers that derive energy from detritus (non-living organic matter).

Nitrogen Fixation

Bacteria converting atmospheric nitrogen into usable ammonia (NH3)

Denitrification

Bacteria converting nitrates back into nitrogen gas & returning it to the atmosphere

Biomagnification

process where a toxin increases at a higher trophic level and impacts the food chain. Transferred from the lower trophic levels up; and at each trophic level the toxin level is magnified.

Greenhouse Effect

natural process where gases in the earth’s atmosphere traps heat to warm up the earth.