RT Journal Article
SR Electronic
T1 Hybrid asexuality as a primary reproductive barrier: on the interconnection between asexuality and speciation
JF bioRxiv
FD Cold Spring Harbor Laboratory
SP 038299
DO 10.1101/038299
A1 Karel Janko
A1 Jan Pačes
A1 Hilde Wilkinson-Herbots
A1 Rui J Costa
A1 Jan Roslein
A1 Pavel Drozd
A1 Nataliia Iakovenko
A1 Jakub Rídl
A1 Jan Kočí
A1 Radka Reifová
A1 Věra Šlechtová
A1 Lukáš Choleva
YR 2016
UL http://biorxiv.org/content/early/2016/01/31/038299.abstract
AB Speciation usually proceeds in a continuum from intensively hybridizing populations until the formation of irreversibly isolated species. Restriction of interspecific gene flow may often be achieved by gradual accumulation of postzygotic incompatibilities with hybrid infertility typically evolving more rapidly than inviability. A reconstructed history of speciation in European loaches (Cobitis) reveals that accumulation of postzygotic reproductive incompatibilities may take an alternative, in the literature largely neglected, pathway through initiation of hybrids’ asexuality rather than through a decrease in hybrids’ fitness. Combined evidence show that contemporary Cobitis species readily hybridize in hybrid zones, but their gene pools are isolated as hybridization produces infertile males and fertile but clonally reproducing females that cannot mediate introgressions. Nevertheless, coalescent analyses indicated intensive historical gene flow during earlier stages of Cobitis diversification, suggesting that non-clonal hybrids must have existed in the past. Revealed patterns imply that during the initial stages of speciation, hybridization between little diverged species produced recombinant hybrids mediating gene flow, but growing divergence among species caused disrupted meiosis in hybrids resulting in their clonality, which acts as a barrier to gene flow.Comparative analysis of published data on other fish hybrids corroborated the generality of our findings; the species pairs producing asexual hybrids were more genetically diverged than those pairs producing fertile sexual hybrids but less diverged than species pairs producing infertile hybrids. Hybrid asexuality therefore appears to evolve at lower divergence than other types of postzygotic barriers and might thus represent a primary reproductive barrier in many taxa.