Browse Teach Curate

Fixation: When Only One Allele Is Left in a Species

Fixation is the hinge of the archaic-sharing argument: a fixed site has no variation, so it cannot carry any association with a trait. Teaching fixation as a frequency of one, reachable by drift as well as by selection, prevents both errors at once.

Questions this Concept answers

Why can a fixed site not explain any difference between people within a species?

jeremy Video

Genetic Drift in Population Genetics

Genetic drift is the random change in allele frequencies from one generation to the next due to chance sampling of gametes in reproduction, an effect that is disproportionately strong in small popula…