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Speciation with gene flow OR speciation and gene flow

In recent years, the rise of non-model pop genomics paired with the development of robust and powerful tests of gene flow [both genome-wide (e.g. f3 tests, D-stats, and rolloff [read here] and treemix) and across in genomic regions (e.g. hapmix, finestructure)] has allowed us to explore the extent of gene flow in in diverged species pairs. While results-to-date likely suffer from biases in ascertainment (i.e. we’re more prone to look for gene flow in cases where it’s likely), and publication (no gene flow might not be a catchy title or result), the weight of evidence suggests that we shouldn’t be shocked by gene flow between recently diverged species/populations . At first blush, evidence for gene flow between species may lead us to think that ‘speciation with gene flow’ [e.g. Feder et. al.)] is common; however, there is a difference between speciation with gene flow vs speciation and gene flow.

The prior describes the case where speciation occurs even with ongoing gene exchange between diverging species-to-be, the later describes minor exchange of genes between good species after speciation is complete. Like the contrast between ‘genomic islands of speciation’ and ‘genomic islands and speciation’, concerns about ‘speciation with gene flow’ and ‘speciation and gene flow’ reflect the extreme caution and strong evidence needed to go from pattern to process in population genomic analyses. Interested readers should check out a recent exciting twitter discussion between Graham Coop, Matt Hahn, Mohamed Noor and Josh Schraiber (below). The take home message is that, in population genomic analyses, we must be careful not to let our excitement about a cool potential process to get ahead of what we can infer from a pattern.


About Yaniv Brandvain

I'm a population geneticist in the department of plant biology at the university of minnesota


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(2/6/17) --Yaniv is Honored to be named a McKnight Land Grant Professor. Read the college announcement here.

(5/15/16) -- New postdoc, Alison Wardlaw, arrives from Toronto and heads directly to the State Fair [pic] Not shown - alison's trip to the mall of america.

(5/15/16) -- In his new paper, postdoc Adam Herman digs in to the historical action of selection on losing incompatibility in Leavenworthia [read the paper in Evolution].

(5/15/16) -- New paper with Alisa Sedghifar and Peter Ralph shows that hybrid incompatibilities should be flanked by large ancestry blocks in hybridizing populations [read the paper in Molecular Ecology].

(4/12/16) -- So proud of and happy for former postdoc, current collaborator, and friend forever, Dena Grossenbacher, who will be starting an assistant professor gig at Cal Poly San. Luis Obispo. CONGRATS DENA!

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