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Title History and extent of introgressive hybridization in Puget Sound rockfishes (Sebastes auriculatus, S. caurinus, and S. maliger)
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Date Accessioned
University/Publisher University of Washington
Abstract Natural hybridization is common in closely related species especially where they invade novel habitat. The patterns of introgressive hybridization are often asymmetrical and are attributed to various influences from selection to gene flow and dispersal. Hybridization has previously been detected in S. auriculatus, S. caurinus, and S. maliger in Puget Sound (the southern Salish Sea) but the details of the history and direction of introgression are incomplete. These Pacific rockfish species are sympatric over most of their geographic range but hybridization has only been detected in Puget Sound. In order to measure interspecific gene flow, we used sequence data from one mitochondrial locus, three nuclear intron loci, and one coding gene to compare interspecific gene flow between collections from the Salish Sea and the Pacific coast. Although ancestral polymorphisms could not be excluded in the analysis of phylogenetic trees, coalescence analysis provided clear evidence for broad-scale, asymmetrical introgression from S. maliger into S. auriculatus and S. caurinus and a much lower incidence of introgression between S. auriculatus and S. caurinus. The absence of F1 hybrids was consistent with historical hybridization events or ongoing, low-level hybridization in the Salish Sea. Although hybrids were found in high frequency, introgressed rockfish in the Salish Sea appear to maintain the morphological characters and coloration of pure parental species morphology. This rockfish hybrid system, with asymmetrical introgression and the maintenance of parental species, may prove useful to study both mechanisms that maintain species boundaries and processes that facilitate speciation.
Subjects/Keywords coalescence; introgression; mitochondria; nuclear introns; phylogenetics; sequence; Fisheries and aquatic sciences; Molecular biology; Fisheries
Contributors Hauser, Lorenz (advisor)
Language en
Rights Copyright is held by the individual authors.
Country of Publication us
Record ID handle:1773/21967
Repository washington
Date Retrieved
Date Indexed 2020-01-07
Issued Date 2013-02-25 00:00:00
Note [] Thesis (Master's) – University of Washington, 2012;

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…distinguish between incomplete lineage sorting and introgressive hybridization in closely related species is to compare gene trees from mitochondrial and several independent nuclear genetic loci (Funk and Omland 2003). The maternally inherited…

…haploid mitochondrial locus is expected to evolve to species monophyly faster than diploid biparentally inherited nuclear loci (Palumbi 2001). Monophyly at nuclear loci genealogies and shared polymorphisms at the mitochondria DNA can therefore be…

…interpreted as evidence for mitochondrial DNA introgression (Redenback and Taylor 2002). However, this assumes that mitochondrial DNA is more susceptible to introgressive hybridization than nuclear loci (Rieseberg and Soltis 1991; Avise 1994…

…segregating sites in both the coastal and Salish Sea populations separately. All individuals used for analysis had complete sequence and locus data. All nucleotide gaps were removed from the sequence data and diploid nuclear data for each species group and…

…changes in populations. To determine non-recombining (NR) blocks from the nuclear DNA sequence, we tested for intralocus recombination using the “4 gamete test” method (Hudson and Kaplan 1985) implemented in DNAsp. The program output…

…used for the IMa2 analysis were one or two of the largest NR blocks from each nuclear locus sequence in addition to the entire Cytb locus sequence (see results). To get a rough estimate of population size (q) as a starting point for…

…expectation from maternal inheritance of a haploid mitochondrial genome compared to bi-parental inheritance of diploid nuclear loci, an inheritance scalar for the cytochrome b mitochondrial locus was set to 0.25 and the nuclear loci each were set to 1. Results…

…x29; (haplotypes 22 and 12, Figure 1.3, Table 1.S1). Trees from nuclear loci were generally less resolved among coastal morphological species, complicating the distinction of hybridization and ancestral polymorphism. The Ets tree had 15…

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