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I.1

What Is Evolution?

Jonathan Losos

OUTLINE

Natural Selection. The process in which individuals with

1. What is evolution? 2. Evolution: Pattern versus process 3. Evolution: More than changes in the gene pool 4. In the light of evolution 5. Critiques and the evidence for evolution 6. The pace of evolution 7. Evolution, humans, and society Evolution refers to change through time as species become modified and diverge to produce multiple descendant species. Evolution and natural selection are often conflated, but evolution is the historical occurrence of change, and natural selection is one mechanism—in most cases the most important—that can cause it. Recent years have seen a flowering in the field of evolutionary biology, and much has been learned about the causes and consequences of evolution. The two main pillars of our knowledge of evolution come from knowledge of the historical record of evolutionary change, deduced directly from the fossil record and inferred from examination of phylogeny, and from study of the process of evolutionary change, particularly the effect of natural selection. It is now apparent that when selection is strong, evolution can proceed considerably more rapidly than was generally envisioned by Darwin. As a result, scientists are realizing that it is possible to conduct evolutionary experiments in real time. Recent developments in many areas, including molecular and developmental biology, have greatly expanded our knowledge and reaffirmed evolution’s central place in the understanding of biological diversity.

GLOSSARY

Evolution. Descent with modification; transformation

a particular trait tend to leave more offspring in the next generation than do individuals with a different trait. Approximately 375 million years ago, a large and...