Introgression and selection shaped the evolutionary history of sympatric sister-species of coral reef fishes (genus: Haemulon)

Abstract
Closely related marine species with large overlapping ranges provide opportunities to study mechanisms of speciation, particularly when there is evidence of gene flow between such lineages. Here, we focus on a case of hybridization between the sympatric sister-species Haemulon maculicauda and H. flaviguttatum, using Sanger sequencing of mitochondrial and nuclear loci, as well as 2422 single nucleotide polymorphisms (SNPs) obtained via restriction site-associated DNA sequencing (RADSeq). Mitochondrial markers revealed a shared haplotype for COI and low divergence for CytB and CR between the sister-species. On the other hand, complete lineage sorting was observed at the nuclear loci and most of the SNPs. Under neutral expectations, the smaller effective population size of mtDNA should lead to fixation of mutations faster than nDNA. Thus, these results suggest that hybridization in the recent past (0.174-0.263Ma) led to introgression of the mtDNA, with little effect on the nuclear genome. Analyses of the SNP data revealed 28 loci potentially under divergent selection between the two species. The combination of mtDNA introgression and limited nuclear DNA introgression provides a mechanism for the evolution of independent lineages despite recurrent hybridization events. This study adds to the growing body of research that exemplifies how genetic divergence can be maintained in the presence of gene flow between closely related species.

Citation
Bernal MA, Gaither MR, Simison WB, Rocha LA (2016) Introgression and selection shaped the evolutionary history of sympatric sister-species of coral reef fishes (genus: Haemulon). Molecular Ecology 26: 639–652. Available: http://dx.doi.org/10.1111/mec.13937.

Acknowledgements
This study was supported by funds of the California Academy of Sciences to LAR, and the Kristina Louie Memorial Fund to MAB. Support for MAB was provided by National Secretary of Science and Technology of Panama (SENACYT) and the Lakeside Foundation (CAS). We are thankful for the support of the Center for Comparative Genomics of CAS, especially Anna Sellas. Thanks to Arturo A. Bocos, Fernando Aranceta, Ruben Sandoval, Hector Reyes Bonilla, Edgardo Ochoa, Ernesto Pena, Irving Bethancourt and the staff of the Smithsonian Tropical Research Institute for help with the collections. This work used the Vincent J. Coates Genomics Sequencing Laboratory at UC Berkeley, supported by NIH S10 Instrumentation Grants S10RR029668 and S10RR027303.

Publisher
Wiley

Journal
Molecular Ecology

DOI
10.1111/mec.13937

Additional Links
http://onlinelibrary.wiley.com/doi/10.1111/mec.13937/full

Relations
Is Supplemented By:
  • [Dataset]
    Bernal, M. A., Gaither, M. R., Simison, W. B., & Rocha, L. A. (2017). Data from: Introgression and selection shaped the evolutionary history of sympatric sister-species of coral reef fishes (genus: Haemulon) (Version 1) [Data set]. Dryad. https://doi.org/10.5061/DRYAD.B9482. DOI: 10.5061/dryad.b9482 Handle: 10754/662362

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