Constitutive ablation
Gene expression that results in cell death.

Constitutive expression
Continuous transcription of a gene in an organism.

Consultand
Individual requesting genetic counseling.

Contig
Group of cloned (copied) pieces of DNA representing overlapping regions of a particular chromosome.

Continuous variation
Phenotypic variation not represented by distinct classes. Such quantitative traits are distributed in an overlapping or continuous fashion between two phenotypic extremes. Multiple genes are usually involved in such variation.

Contrivance
An object or characteristic used or modified to do so different from its usual use.

Convergence
The process by which a similar character evolves independently in two species. Also, a synonym for analogy; that is, an instance of a convergently evolved character, or a similar character in two species that was not present in their common ancestor. Examples include wings (convergent in birds, bats, and insects) and camera-type eyes (convergent in vertebrates and cephalopod mollusks).