Revisiting an Old Riddle: What Determines Genetic Diversity Levels within Species?
Ellen M. Leffler1*, Kevin Bullaughey2#, Daniel R. Matute1#, Wynn K. Meyer1#, Laure Ségurel1,3#, Aarti Venkat1#, Peter Andolfatto4, Molly Przeworski1,2,3*
1 Department of Human Genetics, University of Chicago, Chicago, Illinois, United States of America, 2 Department of Ecology and Evolution, University of Chicago, Chicago, Illinois, United States of America, 3 Howard Hughes Medical Institute, University of Chicago, Chicago, Illinois, United States of America, 4 Department of Ecology and Evolutionary Biology and the Lewis-Sigler Institute for Integrative Genomics, Princeton University, Princeton, New Jersey, United States of America
Abstract
Understanding why some species have more genetic diversity than others is central to the study of ecology and evolution, and carries potentially important implications for conservation biology. Yet not only does this question remain unresolved, it has largely fallen into disregard. With the rapid decrease in sequencing costs, we argue that it is time to revive it.
Citation: Leffler EM, Bullaughey K, Matute DR, Meyer WK, Ségurel L, et al. (2012) Revisiting an Old Riddle: What Determines Genetic Diversity Levels within Species? PLoS Biol 10(9): e1001388. doi:10.1371/journal.pbio.1001388
Published: September 11, 2012
Copyright: © Leffler et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
Funding: E.M.L. was partially supported by National Institutes of Health Grant T32 GM007197. M.P. is a Howard Hughes Early Career Scientist. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.
Competing interests: The authors have declared that no competing interests exist.
* E-mail: emleffler@uchicago.edu (EML); mfp@uchicago.edu (MP)
# These authors contributed equally to this work.
What evolutionary forces maintain genetic diversity in natural populations? How do diversity levels relate to census population sizes (Box 1)? Do low levels of diversity limit adaptation to novel selective pressures? Efforts to address such questions spurred the rise of modern population genetics and contributed to the development of the neutral theory of molecular evolution—the null hypothesis for much of evolutionary genetics and comparative genomics [1]–[3]. Yet these questions remain wide open and, for close to two decades, have been neglected [4]. Most notably, little progress has been made to resolve a riddle first pointed out 40 years ago on the basis of allozyme data: the mysteriously narrow range of genetic diversity levels seen across taxa that vary markedly in their census population sizes [5]. This gap in our understanding is glaring, and may hamper efforts at conservation (e.g., [6]).
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