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A

adaptation

The evolutionary process through which a population becomes better suited to its environment over many generations of natural selection.

adaptive trait

A heritable feature of an individual’s phenotype that improves its chances of survival and reproduction in the existing environment.

adductor muscle

One of usually two large muscles (one anterior, one posterior) that contract to close the shell of a bivalve and maintain it in that condition; the position of these muscles is usually clearly marked on the shell interior as an adductor muscle scar or impression

allele

An alternative form of a gene; one of the different forms of a gene that can exist at a single locus.

allopatric speciation

Speciation in which the evolution of reproductive isolating mechanisms occurs during physical separation of the populations.

anagenesis

Change within a lineage over evolutionary time, as opposed to cladogenesis, the splitting of lineages.

analogous

Having similar function, although different in structure and origin.

anatomy

The science concerned with the shape, structure and the relationship of parts of organisms; also called morphology.

aquaculture

The science of farming organisms that live in water, such as fish, shellfish, and algae

auricles

Ear-shaped structures on the shells of scallops, one of their defining characteristics.