 Bottleneck effect 

1.   Bottleneck effect  Owen Rachael

2. Elephant seals Northern Elephant seals have smaller genetic variation because of a population bottleneck humans inflicted on them in the 1890’s. Hunting made their population size smaller (20!!!) in 10 years. Their population has since regrown to about due to the bottleneck effect the northern seal things have much less genetic variation than the southern elephant seals because the wasn't hunted as much.

3. Population after the event Original population Major catastrophic event