Patterns of Selection

Apply to all non-random evolution mechanisms.

^^Stabilizing Selection:^^ Elimination of traits that do not tally with the average population. (getting rid of the extremes and keeping the intermediaries).

ex. really short bills and really long bills are eliminated and medium length bills are favoured.

*genetic variation decreases

^^Directional Selection:^^ Environment favours individuals with more extreme traits due to sudden change in environment. Increases variation.

  ![ex. Humingbirds migrate to a place with flowers which have longer petals. Shorter petals are no longer functional, so longer onces are favoured.

^^Disruptive Selection:^^ Favours both extreme traits, and eliminates intermediaries. This increases genetic variance.