Evolution of Complex Adaptation
The Genetic Bases and Evolution of Complex Adaptations
University of California-Santa Barbara, USA
A fundamental and long-standing question in biology is how complex, integrated traits like eyes and nervous systems originate during evolution. Yet only very recently have evolutionists begun to uncover the specific genetic changes responsible for the evolution of traits. Starting one hundred and fifty years ago, Charles Darwin argued that even complex traits can evolve by gradual natural selection, whereby heritable variation and differential survival lead to change of traits over time. However, Darwin was unaware of genetics, and he was wrong about the mechanisms of heritability. Not until later was genetics added to evolutionary theory, during a time in the 1930s and 1940s known as the Modern Synthesis. Still, the architects of the Modern Synthesis generally treated genes as anonymous entities and usually ignored the mechanisms responsible for the origins of variation in genes. Although this Modern Synthesis approach allowed for powerful mathematical models that greatly propelled the field of evolution, still missing was an explicit link between evolutionary changes and causal genetic mutations in DNA. Revolutionary progress in molecular biology has finally allowed evolutionists in a few cases to identify the causal genetic mutations that led to evolutionary change. This progress will allow new questions to be realistically tackled over the next several years, for example whether certain classes of change in DNA are more important for evolution than others. One such frontier question involves whether changes in the structural components of genes or changes in the regulatory apparatus of genes are more common fuel for evolutionary change. These frontier studies will soon allow unprecedented insights into the evolutionary history of even the most complex traits.
For further reading: "Evolution in Action" (SCIENCE, Vol. 310, Dec. 2005)