Stable species boundaries despite ten million years of hybridisation in tropical eels

Barth, JMI; Gubili, C; Matschiner, M; Torresen, OK; Watanabe, S; Egger, B; Han, Y-S; Feunteun, E; Sommaruga, R; Jehle, R; Schabetsberger, R

Abstract

Genomic evidence is increasingly underpinning that hybridization between taxa is commonplace, challenging our views on the mechanisms that maintain their boundaries. Here, we focus on seven catadromous eel species (genus Anguilla) and use genome-wide sequence data from more than 450 individuals sampled across the tropical Indo-Pacific, morphological information, and three newly assembled draft genomes to compare contemporary patterns of hybridization with signatures of past introgression across a time-calibrated phylogeny. We show that the seven species have remained distinct for up to 10 million years and find that the current frequencies of hybridization across species pairs contrast with genomic signatures of past introgression. Based on near-complete asymmetry in the directionality of hybridization and decreasing frequencies of later-generation hybrids, we suggest cytonuclear incompatibilities, hybrid breakdown, and purifying selection as mechanisms that can support species cohesion even when hybridization has been pervasive throughout the evolutionary history of clades.

Citation

Barth, J., Gubili, C., Matschiner, M., Torresen, O., Watanabe, S., Egger, B., …Schabetsberger, R. (2020). Stable species boundaries despite ten million years of hybridisation in tropical eels. Nature communications, 11, 1433. https://doi.org/10.1038/s41467-020-15099-x

• Journal Article Type: Article
• Acceptance Date: Feb 7, 2020
• Online Publication Date: Mar 18, 2020
• Publication Date: Mar 18, 2020
• Deposit Date: Mar 18, 2020
• Publicly Available Date: Mar 18, 2020
• Journal: Nature Communications
• Print ISSN: 2041-1723
• Volume: 11
• Pages: 1433
• DOI: https://doi.org/10.1038/s41467-020-15099-x
• Publisher URL: https://doi.org/10.1038/s41467-020-15099-x
• Related Public URLs: https://www.nature.com/ncomms/
• Additional Information: Funders : Austrian Science Fund/University of Salzburg;Norwegian Research Council;DST/NRF South African Research Chair in Inland Fisheries and Freshwater Ecology; Projects : FWF;FRIPRO project; Grant Number: P28381-B29; Grant Number: 275869; Grant Number: 110507