Adaptive protein evolution in Drosophila


For over 30 years a central question in molecular evolution has been whether natural selection plays a substantial role in evolution at the DNA sequence level1,2. Evidence has accumulated over the last decade that adaptive evolution does occur at the protein level3,4, but it has remained unclear how prevalent adaptive evolution is. Here we present a simple method by which the number of adaptive substitutions can be estimated and apply it to data from Drosophila simulans and D. yakuba. We estimate that 45% of all amino-acid substitutions have been fixed by natural selection, and that on average one adaptive substitution occurs every 45 years in these species.

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Figure 1: The distribution of 1,000 bootstrap values of \(\overline{α}\) for the divergence between Drosophila simulans and D. yakuba for genes in which Ps > 5.


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We thank B. Charlesworth, C.-I. Wu, S. Otto, M. Whitlock, T. Johnson, P. Awadalla, J. Gillespie, G. McVean and P. Keightley for helpful discussions, and E. Moriyama for help with data collection. N.G.C.S. was funded by the Biotechnology and Biological Sciences Research Council (BBSRC) and A.E.-W. is funded by the Royal Society and the BBSRC.

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Correspondence to Adam Eyre-Walker.

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Smith, N., Eyre-Walker, A. Adaptive protein evolution in Drosophila. Nature 415, 1022–1024 (2002).

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