title: 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 (0.174-0.263 Ma) 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.
authors.affiliation: Integrative Systems Biology Lab, Division of Biological and Environmental Sciences and Engineering, King Abdullah University of Science and Technology, 23955-6900 Thuwal, Kingdom of Saudi Arabia.|Institute for Biodiversity, Science and Sustainability, California Academy of Sciences, 55 Music Concourse Drive, San Francisco, CA, 94118, USA.
authors.forename: Moisés A
authors.initials: MA
authors.lastname: Bernal
authors.affiliation: Institute for Biodiversity, Science and Sustainability, California Academy of Sciences, 55 Music Concourse Drive, San Francisco, CA, 94118, USA.|School of Biological and Biomedical Sciences, Durham University, South Road, Durham, DH1 3LE, UK.
authors.forename: Michelle R
authors.initials: MR
authors.lastname: Gaither
authors.affiliation: Center for Comparative Genomics, California Academy of Sciences, 55 Music Concourse Drive, San Francisco, CA, 94118, USA.
authors.forename: W Brian
authors.initials: WB
authors.lastname: Simison
authors.affiliation: Institute for Biodiversity, Science and Sustainability, California Academy of Sciences, 55 Music Concourse Drive, San Francisco, CA, 94118, USA.
authors.forename: Luiz A
authors.initials: LA
authors.lastname: Rocha
mesh_terms: D000818:Animals; D057894:Coral Reefs; D004272:DNA, Mitochondrial / Q000235:genetics; D051456:Gene Flow; D006824:Hybridization, Genetic; D010473:Perciformes / Q000145:classification*; D010802:Phylogeny; D020641:Polymorphism, Single Nucleotide; D012641:Selection, Genetic; D017422:Sequence Analysis, DNA; D061350:Sympatry
chemical_list: D004272:DNA, Mitochondrial
keywords: RADSeq; Tropical Eastern Pacific; gene flow; genomics; hybridization; mito-nuclear discrepancies; speciation