This edition: Microevolution
Charles Darwin’s theory of evolution by natural selection is presented by John Moore, who discusses its major concepts. Additional historical insight into the theory of evolution is discussed by Ernst Mayr who further defined “species” in the 1940s. This introduction to the subject gives way to a story of unusual mosquitoes that have developed resistance, through mutation and natural selection, to most current forms of insecticides. How are mosquito populations affected by genetic and environmental conditions? In evaluating the insects’ response to the pressure of insecticides, the program discusses selection pressures.
Divergence and various forms of isolation—including geographic, reproductive, structural, and behavioral—are illustrated by plant and animal life on a California coastal island. Misty Gay and Allan Fone show examples of plants on Catalina Island that evolved differently from their counterparts on the mainland. Because of specific environmental pressures unlike those on the mainland, animals on the island evolved into various subspecies. Examples such as the Dwarf Gray Fox show mechanisms that prevent interbreeding, such as isolation of gametes and isolation through time.