| A | B |
|---|
| Natural selection | organisms best suited to the environment are the ones most likely to survive and reproduce |
| Competition | the fight among living things to get what they need for survival |
| Variation | a difference in traits between organisms within a population |
| Fitness | the ability of an organism to live, survive, and reproduce in that environment |
| Gene flow | the change in the occurrence of genes in a population |
| Immigration | occurs when organisms enter into a new population |
| Emigration | occurs when organisms leave a population |
| Bottlenecking | when a large population is reduced to a few individuals and the genes of following generations become very similar |
