Why do brown bears and polar bears have different teeth?

In a relatively small iguana population the allelic frequency is tracked for three generations. webbing is a recessive allele; no webbing is the dominant allele. during one very rainy spring and summer, a flood washes all the iguana without webbed feet out to sea. by the fall, and three generations later, you have the gene pool seen here.

What is called the "building block" of life?

Based on the data in your tables, did the light-colored moths have a higher or lower survival rate after the industrial revolution?