* Gene Flow: This refers to the movement of genes between populations. It keeps populations genetically similar.
* Isolation: When populations are separated geographically, they can no longer interbreed. This stops gene flow.
* Genetic Divergence: As isolated populations adapt to different environments, they accumulate different mutations and genetic variations over time. This leads to genetic divergence.
* Reproductive Isolation: Eventually, these differences may become so significant that the isolated populations can no longer interbreed even if they come back into contact. This is called reproductive isolation and marks the formation of new species.
In simpler terms:
Imagine two groups of squirrels living on opposite sides of a large canyon. They can't cross the canyon, so they are geographically isolated. Over time, each group will adapt to its own environment, leading to genetic differences. Eventually, these differences may make them so different that they can't interbreed, resulting in two distinct species of squirrels.
Key takeaway: Geographic isolation is a powerful force driving speciation because it prevents gene flow, allowing populations to evolve independently and eventually become reproductively isolated.
