Glossary

basal metabolic rate (BMR)

The minimum metabolic rate of an endotherm.

directional selection

Occurs when conditions favour individuals expressing one extreme of a phenotype range, thereby shifting a population's frequency curve for the phenotypic character in one direction.

disruptive selection

Selection that favours individuals with the smallest and largest values of a trait. These individuals have the highest fitness and individuals with intermediate values are at a fitness disadvantage.

ectotherms

An organism that relies on external heat sources to maintain a body temperature within limits.

endotherms

Animals that have a nearly uniform body temperature, maintained independently of ambient temperature, largely by heat derived from metabolism.

flyway

A long-distance migration corridor. There are three main global ones for migrating birds.

homeostasis

Maintenance of a stable internal state by regulation.

homeotherms

Animals that have a nearly uniform body temperature, maintained independently of ambient temperature, largely by heat derived from metabolism. Older term for endotherms.

metabolic rate

The amount of energy used by an organism in unit time.

negative feedback

A control mechanism that reacts to a change in the output of the system by initiating a restoring action.

partial migration

Describes the behaviour of a population on the same breeding grounds where some individuals remain throughout the year and others migrate to avoid adverse condition.

phenotype

The characteristics and physical attributes of an organism controlled by the genotype.

poikilotherms

An organism that relies on external heat sources to maintain a body temperature within limits Older term for ectotherms.

stabilising selection

Occurs where there is an optimal value for the trait of interest. This means that selection acts against both extreme phenotypes and favours intermediate variants which have the highest fitness.

telemetry

An automated process for collecting data remotely, for example encoding position data on a radio signal.

thermoneutral zone

The range of temperatures over which the metabolic rate is equal to the basal value.

variation

Differences between individuals of a species, excluding those associated with sex, age or stage of life cycle.