What is likely the cause of the clinal decrease in type B blood from East Asia to Western Europe?

Question

Quizplus · Accepted Answer

Gene flow, or the movement of individuals and their genes from one population to another, is the most likely cause of the clinal decrease in type B blood from East Asia to Western Europe. This is because populations that are geographically closer are more likely to exchange genes than those that are farther apart. As a result, gene flow can lead to a decrease in the frequency of certain alleles or traits in a particular population over time.

What Is Likely the Cause of the Clinal Decrease in Type