High-resolution mapping reveals hundreds of genetic incompatibilities in hybridizing fish species
- Princeton University, United States
- Texas A&M University, United States
Abstract
Hybridization is increasingly being recognized as a common process in both animal and plant species. Negative epistatic interactions between genes from different parental genomes decrease the fitness of hybrids and can limit gene flow between species. However, little is known about the number and genome-wide distribution of genetic incompatibilities separating species. To detect interacting genes, we perform a high-resolution genome scan for linkage disequilibrium between unlinked genomic regions in naturally occurring hybrid populations of swordtail fish. We estimate that hundreds of pairs of genomic regions contribute to reproductive isolation between these species, despite them being recently diverged. Many of these incompatibilities are likely the result of natural or sexual selection on hybrids, since intrinsic isolation is known to be weak. Patterns of genomic divergence at these regions imply that genetic incompatibilities play a significant role in limiting gene flow even in young species.
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Ethics
Animal experimentation: The procedures used in this study were approved by the Institutional Animal Care and Use Committee at Texas A&M University (Protocols # 2010-111 and 2012-164). Procedures were designed to minimize animal stress and suffering by using anesthesia during fin clipping and minimal handling of the fish. Samples were collected from the wild under Mexican federal collector's license FAUT-217 to W. Scott Monks.
Copyright
© 2014, Schumer et al.
This article is distributed under the terms of the Creative Commons Attribution License permitting unrestricted use and redistribution provided that the original author and source are credited.
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High-resolution mapping reveals hundreds of genetic incompatibilities in hybridizing fish species
eLife 3:e02535.
https://doi.org/10.7554/eLife.02535
Further reading
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How do different species remain distinct if they can mate with each other to produce hybrid offspring?
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- Evolutionary Biology
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Cattle (Bos taurus) play an important role in the life of humans in the Iberian Peninsula not just as a food source but also in cultural events. When domestic cattle were first introduced to Iberia, wild aurochs (Bos primigenius) were still present, leaving ample opportunity for mating (whether intended by farmers or not). Using a temporal bioarchaeological dataset covering eight millennia, we trace gene flow between the two groups. Our results show frequent hybridisation during the Neolithic and Chalcolithic, likely reflecting a mix of hunting and herding or relatively unmanaged herds, with mostly male aurochs and female domestic cattle involved. This is supported by isotopic evidence consistent with ecological niche sharing, with only a few domestic cattle possibly being managed. The proportion of aurochs ancestry in domestic cattle remains relatively constant from about 4000 years ago, probably due to herd management and selection against first generation hybrids, coinciding with other cultural transitions. The constant level of wild ancestry (~20%) continues into modern Western European breeds including Iberian cattle selected for aggressiveness and fighting ability. This study illuminates the genomic impact of human actions and wild introgression in the establishment of cattle as one of the most important domestic species today.
