Scientists have studied the guppy populations in the St. Johns River. They vary in size. Approximately half the population are large guppies and the other half are small guppies. Guppies are preyed upon by birds that tend to eat larger guppies.

1. What type of evolution do you think this is? Why?

2.

What variations are present in this population?

3.

What type of guppy is most fit? Who or what decides which guppies can reproduce?

4.

How do you think the guppy population will change? What traits will become more common?