Evolution

Where does life’s diversity come from? Where do new species come from? Why do some species go extinct?

These are just a few of the questions that can be answered by an understanding of evolution, genetics, and biodiversity. These disciplines explain the mechanisms that shape how organisms interact with their environment and, in turn, how the environment shapes organisms over many generations.

To study ecology without an understanding of evolutionary theory is to watch a sporting event without first learning the rules; players run, points are scored, whistles shrill, but the guiding principles underlying these events remain a mystery. With an understanding of the rules, however, even the smallest intricacies of the game can be appreciated, even loved. So it is with ecology: evolution provides a canon by which we may better understand the interactions of organisms with their environments.

Evolution is a process that results in changes in the genetic content of a population over time. There are two general classes of evolutionary change: microevolution and macroevolution. Microevolutionary processes are changes in allele frequencies in a population over time. Three main mechanisms cause allele frequency change: natural selection, genetic drift, and gene flow. Macroevolution, on the other hand, refers to change at or above the level of the species.

Advances in technology have given us tools that have dramatically advanced our understanding of how evolution occurs. We now know that two-thirds of the genes known to be involved in cancer in humans are also found in the fruit fly. In addition to its implication for human health, advances in these fields have benefited ecological studies as well. Conservationists in South Africa have used DNA technology to learn about more about genetic diversity in cheetahs, and are using this information to help keep cheetahs from becoming extinct. Further advances will bring wide applications in agriculture, conservation, and environmental restoration efforts.

To develop a rich understanding of the core topics of evolution, begin with this introductory overview, and then explore the other summaries you’ll find below.