C4.1 Vocabulary for Interspecific Competition & Ecology Terms

Population

interacting groups of organisms of the same species living in the same area.

Sample

a subset of a whole population or habitat used to estimate the values that might have been obtained if every individual or response was measured.

Random sampling

a method of choosing a sample from a population without any bias.

Sampling error

statistical errors that arise when a sample does not represent the whole population, ie it is the difference between the real values of the population and the values derived by using samples from the population.

Stratified sampling

used in areas that contain two or more different habitat types; the technique takes into account the proportional area of different habitat types and samples each one accordingly.

Systematic sampling

used where the study area includes an environmental gradient. A transect is used to sample systematically along an environmental gradient.

Variation

a quantitative measure of the distribution (spread or clustering) of the values in a data set.

Range

the difference between the largest and smallest data values.

Standard deviation (SD)

the spread of a set of normally distributed data from the mean of the sample; is a measure of the variability of a population from a sample. A small standard deviation indicates the data are more reliable.

Normal distribution

a data-set distribution that is symmetrical about the mean, forming a bell-shaped curve.

Carrying capacity

the maximum number of individuals of a species that can be supported by a given environment.

Negative feedback

feedback that tends to counteract any deviation from equilibrium and promotes stability.

Density-dependent

factors that lower the birth rate or raise the death rate as a population grows.

Community

a group of different species living in an area.

Intraspecific competition

competition between individuals of the same species.

Interspecific competition

competition between individuals of different species.

Cooperation

the action or process of working together.

Altruism

behavior of an animal that benefits another at its own expense. Biologist call a behavior pattern altruistic if it increases the number of offspring produced by the recipient and decreases that of the altruist.

Mutualism

an interaction in which both species derive benefit. This is a specific type of symbiotic relationship.

Parasitism

a relationship there where one organism (the parasite) benefits at the expense of another (the host) from which it derives its food.

Pathogenicity

the capacity of a microbe to cause damage in a host resulting in disease.

Root nodule

small swelling on the root of plants that contain symbiotic nitrogen-fixing bacteria.

Symbiotic

a close and long-term biological interaction between two different species.

Mycorrhiza plural mycorrhizae

a fungus that grows in association with the roots of a plant in a symbiotic relationship.

Hypotheses

a provisional explanation of an observed phenomena or event that can be investigated using the scientific method; when using a statistical test, the hypothesis states that there is a statistically significant difference between two variables.

Null hypothesis

there is no statistically significant difference between two variables.

Predator-prey relationship

the relationship of population size is due to predation of one species (the predator) on another (the prey).

Top-down control

changes in the food chain occur at the top trophic level and then impact the trophic levels lower in the food chain.

Bottom-up control

changes in the food chain occur at the lowest trophic level (producers) and then impact the trophic levels higher in the food chain.

Allelopathy

chemical inhibition of one plant (or other organism) by another, due to the release of chemicals (allelochemicals) that act as germination or growth inhibitors.