Ancient polymorphisms and divergence hitchhiking contribute to genomic islands of divergence within a poplar species complex.
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Ma T, Wang K, Hu Q, Xi Z, Wan D, Wang Q, Feng J, Jiang D, Ahani H, Abbott RJ, Lascoux M, Nevo E, Liu J
Proc. Natl. Acad. Sci. U.S.A. 115 (2) E236-E243 [2018-01-09; online 2017-12-26]
How genome divergence eventually leads to speciation is a topic of prime evolutionary interest. Genomic islands of elevated divergence are frequently reported between diverging lineages, and their size is expected to increase with time and gene flow under the speciation-with-gene-flow model. However, such islands can also result from divergent sorting of ancient polymorphisms, recent ecological selection regardless of gene flow, and/or recurrent background selection and selective sweeps in low-recombination regions. It is challenging to disentangle these nonexclusive alternatives, but here we attempt to do this in an analysis of what drove genomic divergence between four lineages comprising a species complex of desert poplar trees. Within this complex we found that two morphologically delimited species,
PubMed 29279400
DOI 10.1073/pnas.1713288114
Crossref 10.1073/pnas.1713288114
pii: 1713288114
pmc: PMC5777044