Evolution

3. When a few individuals establish a new population, and their genetic traits become common in that group (e.g., Amish with six fingers).
7. One extreme trait is favored due to gradual environmental change (e.g., horses becoming larger over time).
8. Species reproduce at different times (season/day).
10. Random evolutionary changes in small breeding populations.
11. Intermediate traits are favored; extremes are selected against (e.g., average baby weight has highest survival).

1. Individuals with favorable traits survive and reproduce more; includes overproduction, variation, competition, and differential survival.
2. Extreme traits are favored, and the average is selected against; happens during rapid environmental changes.
4. Traits that improve mating success spread through populations (e.g., bright feathers in birds).
5. A sharp reduction in the size of a population due to environmental events, leading to loss of genetic diversity (e.g., cheetahs).
6. Species live in the same area but occupy different habitats.
9. The migration of individuals between different populations followed by breeding; populations are not isolated.