-Remember, a population will remain unchanged unless an outside force acts on them.
Tongue rolling
-2003
TR = .75 A_
NTR = .25 aa
-2013
TR = .80 A_
NTR = .20 aa
What force changed this? Was it just chance?
I. Genetic Drift - allele/gene frequencies change by chance in a population.
This is more likely to happen in a SMALL population. There are 2 events
that will promote genetic drift:
A. The Founder Effect - when a small number of individuals migrate away and become genetically isolated. A small amount of individuals have many descendants. ex. Amish
B. Population Bottleneck - when a large population is reduced down to very small size. ex. Blackfooted ferret, cheetah
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