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A lizard with two tales: what diversification within Sceloporus occidentalis teaches us about species formation
  • Ricardo Pereira,
  • Sonal Singhal
Ricardo Pereira
Ludwig-Maximilians-Universitat Munchen
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Sonal Singhal
CSU
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Abstract

In 1859, Charles Darwin proposed that species are not fundamentally different from subspecies or the varieties from which they evolve. A century later, Dobzhansky (1958) suggested that many such lineages are ephemeral and are likely to revert differentiation through introgression (Fig. 1A); only a few evolve complete reproductive isolation and persist in sympatry. In this issue of Molecular Ecology, Bouzid et al. (2021) show how new analytical methods, when applied to genome data, allow us to more precisely determine whether or not species formation follows the paths outlined by Darwin and Dobzhansky (Fig. 1B). The authors study the diversification of the lizard Sceloporus occidentalis, finding a continuum of genetic interactions between the preservation of genetic identity to genetic merger, analogous to what is exemplified by ring species. In doing so, they teach us two tales on species formation: that lineages are fractal byproducts of evolutionary processes such as genetic drift and selection, and that lineages are often ephemeral and do not always progress into species. Studying ephemeral lineages like those in S. occidentalis allows us to capture divergence at its earliest stages, and potentially to determine the factors that allow lineages to remain distinct despite pervasive gene flow. These lineages thus serve as a natural laboratory to address long standing hypotheses on species formation.
25 Oct 2021Submitted to Molecular Ecology
26 Oct 2021Assigned to Editor
26 Oct 2021Submission Checks Completed
05 Nov 2021Reviewer(s) Assigned
24 Nov 2021Review(s) Completed, Editorial Evaluation Pending
03 Dec 2021Editorial Decision: Accept
Jan 2022Published in Molecular Ecology volume 31 issue 2 on pages 407-410. 10.1111/mec.16321