Biodiversity Glossary

Adaptation--n. A feature of an organism that confers fitness; v. the process of acquiring such a feature through evolution by natural selection

Common descent--all living organisms descended from common ancestor

Cytrochrome C--an enzyme found in almost all organisms that has been used to show the evolutionary distance between different organisms

Evolution--change in gene frequency through time

Fitness--having features that allow survival to produce offspring that reproduce (context-dependent)

Homologous--having the same structure, owing to inheritance from a common ancestor
 

Natural selection-- differential success in reproduction

Pharyngeal slits--a common structure found in the embryos of all vertebrates.  In fish, these structures develop into the openings to the gills.   In humans, the pharyngeal slits develop into the eustachian tubes.  The existence of these structures shows evidence of a common ancestor.