Mass of genes rather than master genes underlie the genomic architecture of amphibian speciation
Christophe Dufresnes, Alan Brelsford, Daniel L. Jeffries, Glib Mazepa, Tomasz Suchan, Daniele Canestrelli, Alfredo G. Nicieza, Luca Fumagalli, Sylvain Dubey, Íñigo Martínez-Solano, Spartak N. Litvinchuk, Miguel Vences, Nicolas Perrin, Pierre‐André Crochet
Abstract
Significance Reproductive isolation is instrumental to the formation of new species (speciation), but it remains largely enigmatic how many incompatibilities are required to prevent hybridization and where they lie across the genome. By studying patterns of admixture in amphibian hybrid zones, we found that reproductive isolation is initiated by numerous small-effect incompatibilities scattered across the genome rather than concentrated in a few important genes. Unlike mammals and birds, in which Y/W degeneracy is a major cause of hybrid dysfunctions, the undifferentiated sex chromosomes of amphibians do not always host more genetic incompatibilities than other chromosomes. These combined results might explain why amphibian speciation is relatively slow, and its clock-like dynamics offer practical perspectives to categorize evolutionary lineages into species or subspecies.