Aa Aa Aa Natural selection, genetic drift, and gene flow are the mechanisms that cause changes in allele frequencies over time. When one or more of these forces are acting in a population ...

Aa Aa Aa Natural selection, genetic drift, and gene flow are the mechanisms that cause changes in allele frequencies over time. When one or more of these forces are acting in a population ...

Because of their closed population stemming from a small number of German immigrants -- about 200 individuals -- the Amish carry unusual concentrations of gene mutations that cause a number of ...

That is, changes affect the "letters" (four different types of chemical units) in the genetic blueprints -- the genes-- that are carried in their cells. Each gene is a chemical recipe for a ...