American Society of Naturalists

A membership society whose goal is to advance and to diffuse knowledge of organic evolution and other broad biological principles so as to enhance the conceptual unification of the biological sciences.

“The biased evolution of generation time”

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Mélissa Verin, Salomé Bourg, Frédéric Menu, and Etienne Rajon

Long generation times could evolve neutrally as a consequence of turnover bias

Evolution proceeds through the appearance and fixation of heritable changes such as genetic mutations. Selection informs us on the latter—how likely is a mutation that has appeared to reach fixation. Nonetheless, the appearance of mutations can also be important, but is often ignored in evolutionary studies. For instance, mutation biases—whereby some mutations are more likely to appear than others—are well known to impact molecular traits such as codon usage. The role of such biases in the evolution of phenotypic traits is unknown but presumably restricted.

In this study, Mélissa Verin (now a PhD student in Munich) and her colleagues at the University of Lyon show that a different kind of bias can affect the evolution of phenotypic traits such as adult longevity or development time—in fact, any trait correlated with the generation time. They model the evolution of such traits in a context where none is given a selective advantage, to focus on the “appearance” part of the evolutionary process, and find that the genotypes with the longest generation times were the most likely to evolve. Their work provides a new, non-adaptive hypothesis for the evolution of species with long generation times. Read the Article