11.3 Other Mechanisms of Evolution
Natural selection is not the only mechanism through which populations evolve.
11.3 Other Mechanisms of Evolution
Gene flow is the movement of alleles between populations.
• occurs when individuals join new populations and reproduce.
• keeps neighboring populations similar.
• Low gene flow increases the chance that two populations will evolve into different species. bald eagle migration
11.3 Other Mechanisms of Evolution
Genetic drift- a change in allele frequencies due to chance.
• causes a loss of genetic diversity.• most common in small populations.
11.3 Other Mechanisms of Evolution
The Bottleneck Effect- genetic drift that occurs after an event greatly reduces the size of population.
* Alleles can be lostExamples
Over HuntingNatural Disasters
11.3 Other Mechanisms of Evolution
The founder effect- genetic drift that occurs after a small number of individuals colonize a new area.