Genetic Diversity

The Founder effect is where a small group of a species reproduces, creating a large population. But the diversity is small in comparison to the original species as a whole, this is because the small group of the species that reproduced have a limited amount of diversity, that might not represent the original species as a whole

Genetic Bottleneck -

Genetic bottleneck is where a species is nearly wiped out due to either chance or human interference. The small population then tries to reproduce, but they have a little genetic diversity and therefore no matter how large the population is, the genetic diversity will always be smaller than that of the original species