Three ways natural selection can alter variation in a population
1. Directional selection
: Acts against individuals at one of the phenotypic extremes.
- Common during periods of environmental change, or migration to a different habitat.
2. Disruptive selection
: Favours individuals at both extremes of the phenotypic range.
- May occur in patchy habitats.
- Animals camouflaged on different backgrounds.
3. Sexual selection
: May lead to phenotypic differences between males and females (sexual dimorphism).
Define Allopatric Speciation
The formation of new species in populations that are geographically isolated from one another.
Ex. The formation of the Grand Canyon through erosion separated widespread antelope ground squirrel species into 2 species.
Define Sympatric Speciation
The formation of a new species in populations that live in the same geographical area.
Study Guide for Biology Final