The Bottleneck Effect

The Bottleneck Effect: The allele frequency in the population is altered due to a catastrophic event.

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Example: Orange=YY, Yellow=Yy, Green=yy

3:3:1

A Happy Colony Of Giraffes

Then Suddenly... A FIRE COMES

2:1:0

Only A Small Number Of Giraffes Survive

The Dominant Allele is More Common (Y:y = 5:1)