Meeting Abstract

14.2  Friday, Jan. 4  Revealing extensive reticulate evolution in Xiphophorus fishes using high-throughput phylogenomics CUI, R.*; SCHUMER, M.; KRUESI, K.; ANDOLFATTO, P.; ROSENTHAL, G.; Texas A&M University; Princeton University; Universidad Nacional Autónoma de México; Princeton University; Texas A&M University melop@tamu.edu

Recent research has demonstrated that hybridization, a process once thought rare in animals, is remarkably common. Though hybridization presents challenges in reconstructing phylogenies, it may play an important role in adaptation (and potentially speciation) in many species. In the present study we use next-generation sequencing techniques to examine phylogenetic relationships, historical gene flow and its implications in biogeographic patterns and trait evolution in a genus of freshwater fish (Xiphophorus). We found extensive ancient gene flow between and within clades. Two species were found to contain almost even-admixture of genomes from different ancestries, making them good candidates for hybrid speciation. Other species contained smaller proportions from the minor ancestry. Cyto-nuclear conflict of topology was found to be an unreliable indicator of hybridization. Sexually selected traits can be better optimized on a reticulate phylogeny and the sword ornament may have spread through hybridization. The new phylogeny also shed light on palaeobiogeography of the genus. We identified multiple secondary invasions by platyfishes towards the north across the trans-mexican volcanic belt, followed by hybridization with earlier settlers. Our study highlights the potential role of hybridization in these fishes. QTL mapping of ecologically or sexually important traits will allow us to investigate in more detail the role of introgression in adaptation and speciation.