New Paper: Balancing selection and drift in a polymorphic salamander metapopulation

Historical resurveys of polymorphisms have offered efficient insights about evolutionary mechanisms, but often neglect the more comprehensive view afforded by metapopulation and landscape-scale perspectives. Here, we resurveyed a metapopulation of spotted salamanders (Ambystoma maculatum) to understand the evolutionary drivers of frequency variation in an egg mass colour polymorphism. We found that this metapopulation was demographically, phenotypically and environmentally stable over the last three decades. However, we also found clear evidence for rapid ongoing evolution in this metapopulation—genetic drift and balancing selection. Although we cannot identify the balancing mechanism from these data, our findings present a clear view of contemporary evolution in color morph frequency and demonstrate the importance of metapopulation-scale studies for capturing a broad range of evolutionary dynamics.

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Giery, S.T., M. Zimova, D.L. Drake, and M.C. Urban. 2021. Balancing selection and drift in a polymorphic salamander metapopulation. Biology Letters. 17(4): 20200901. https://doi.org/10.1098/rsbl.2020.0901.