Genomic islands of divergence in the Yellow Tang and the Brushtail Tang Surgeonfishes |
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Authors: | Giacomo Bernardi Nicole Crane |
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Affiliation: | Department of Ecology and Evolutionary Biology, University of California Santa Cruz, Santa Cruz, CaliforniaOne People One Reef, 100 McAllistair Way, Santa Cruz, CA, 95060, USA. |
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Abstract: | The current ease of obtaining thousands of molecular markers challenges the notion that full phylogenetic concordance, as proposed by phylogenetic species concepts, is a requirement for defining species delimitations. Indeed, the presence of genomic islands of divergence, which may be the cause, or in some cases the consequence, of speciation, precludes concordance. Here, we explore this issue using thousands of RAD markers on two sister species of surgeonfishes (Teleostei: Acanthuridae), Zebrasoma flavescens and Z. scopas, and several populations within each species. Species are readily distinguished based on their colors (solid yellow and solid brown, respectively), yet populations and species are neither distinguishable using mitochondrial markers (cytochrome c oxidase 1), nor using 5193 SNPs (pairwise Φst = 0.034). In contrast, when using outlier loci, some of them presumably under selection, species delimitations, and strong population structure follow recognized taxonomic positions (pairwise Φst = 0.326). Species and population delimitation differences based on neutral and selected markers are likely due to local adaptation, thus being consistent with the idea that these genomic islands of divergence arose as a consequence of isolation. These findings, which are not unique, raise the question of a potentially important pathway of divergence based on local adaptation that is only evident when looking at thousands of loci. |
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Keywords: | outlier loci population genomics Species delimitations
Zebrasoma flavescens
Zebrasoma scopas
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