Chapter 16: Variation and Population Genetics

Look around your classroom – how many people in the room look just like you?  What is the makeup of the class in terms of hair, eye or skin color?  What about height?  You will find that there is some variation in all of these traits. Much of that variation has a genetic component and all of the variation relates to information.  In this chapter you will consider information at the level of the individual, first by investigating the causes of variation among individuals, then by examining how genetic information within individuals plays out at the population level.  You will learn how genetic and environmental changes have led to variation within species. 

The barnacle Chthamalus anisopoma is a common species in the Gulf of California. It attaches to a hard substrate and has two shell forms, one shaped like a volcano, as most of these are, and one shaped as if the volcano were bent over. Information in the environment triggers the growth of different morphs in individuals.  Courtesy of Curt Lively, Bloomington, IN.


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