Hybridization Dynamics between Colorado's Native Cutthroat Trout and Introduced Rainbow Trout

Metcalf, Jessica L.; Siegle, Matthew R.; Martin, Andrew P.

doi:10.1093/jhered/esm118

Cited by 29 publications

(31 citation statements)

References 27 publications

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“…In some cases where human-mediated introgression has been implicated, discordance also does not appear to be extensive. For instance, in lakes where rainbow trout (Oncorhynchus mykiss) have been introduced and allowed to hybridize with native cutthroat trout (O. clarkii), mtDNA shows a bias towards O. mykiss haplotypes, beyond what would be expected based on nuclear genotypes, but not to complete fixation (Metcalf et al 2008).…”

Section: B I O G E O G R a P H Y O F M I T O -N U C L E A R D I S C Omentioning

confidence: 99%

The biogeography of mitochondrial and nuclear discordance in animals

2012

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Combining nuclear (nuDNA) and mitochondrial DNA (mtDNA) markers has improved the power of molecular data to test phylogenetic and phylogeographic hypotheses and has highlighted the limitations of studies using only mtDNA markers. In fact, in the past decade, many conflicting geographic patterns between mitochondrial and nuclear genetic markers have been identified (i.e. mito-nuclear discordance). Our goals in this synthesis are to: (i) review known cases of mito-nuclear discordance in animal systems, (ii) to summarize the biogeographic patterns in each instance and (iii) to identify common drivers of discordance in various groups. In total, we identified 126 cases in animal systems with strong evidence of discordance between the biogeographic patterns obtained from mitochondrial DNA and those observed in the nuclear genome. In most cases, these patterns are attributed to adaptive introgression of mtDNA, demographic disparities and sex-biased asymmetries, with some studies also implicating hybrid zone movement, human introductions and Wolbachia infection in insects. We also discuss situations where divergent mtDNA clades seem to have arisen in the absence of geographic isolation. For those cases where foreign mtDNA haplotypes are found deep within the range of a second taxon, data suggest that those mtDNA haplotypes are more likely to be at a high frequency and are commonly driven by sex-biased asymmetries and ⁄ or adaptive introgression. In addition, we discuss the problems with inferring the processes causing discordance from biogeographic patterns that are common in many studies. In many cases, authors presented more than one explanation for discordant patterns in a given system, which indicates that likely more data are required. Ideally, to resolve this issue, we see important future work shifting focus from documenting the prevalence of mito-nuclear discordance towards testing hypotheses regarding the drivers of discordance. Indeed, there is great potential for certain cases of mitochondrial introgression to become important natural systems within which to test the effect of different mitochondrial genotypes on whole-animal phenotypes.

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Section: B I O G E O G R a P H Y O F M I T O -N U C L E A R D I S C Omentioning

confidence: 99%

The biogeography of mitochondrial and nuclear discordance in animals

2012

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“…2001; Metcalf et al. 2008), with most populations of taxa such as westslope cutthroat trout ( O. c. lewisi ) thought to be hybridized with nonnative rainbow trout or Yellowstone cutthroat trout ( O. c. bouvieri ; Allendorf et al. 2001, 2013; Shepard et al.…”

Section: Introductionmentioning

confidence: 99%

Patterns of hybridization among cutthroat trout and rainbow trout in northern Rocky Mountain streams

McKelvey

Young

Wilcox

et al. 2016

Ecology and Evolution

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Introgressive hybridization between native and introduced species is a growing conservation concern. For native cutthroat trout and introduced rainbow trout in western North America, this process is thought to lead to the formation of hybrid swarms and the loss of monophyletic evolutionary lineages. Previous studies of this phenomenon, however, indicated that hybrid swarms were rare except when native and introduced forms of cutthroat trout co‐occurred. We used a panel of 86 diagnostic, single nucleotide polymorphisms to evaluate the genetic composition of 3865 fish captured in 188 locations on 129 streams distributed across western Montana and northern Idaho. Although introgression was common and only 37% of the sites were occupied solely by parental westslope cutthroat trout, levels of hybridization were generally low. Of the 188 sites sampled, 73% contained ≤5% rainbow trout alleles and 58% had ≤1% rainbow trout alleles. Overall, 72% of specimens were nonadmixed westslope cutthroat trout, and an additional 3.5% were nonadmixed rainbow trout. Samples from seven sites met our criteria for hybrid swarms, that is, an absence of nonadmixed individuals and a random distribution of alleles within the sample; most (6/7) were associated with introgression by Yellowstone cutthroat trout. In streams with multiple sites, upstream locations exhibited less introgression than downstream locations. We conclude that although the widespread introduction of nonnative trout within the historical range of westslope cutthroat trout has increased the incidence of introgression, sites containing nonadmixed populations of this taxon are common and broadly distributed.

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“…Hybrids can involve two distinct species, strains or populations within a single species (Duchesne and Bernatchez 2007) and in order to successfully identify the hybrid forms, it requires a certain level of genetic information, especially when parental species are phylogenetically closely related, such as the Atlantic and the spotted wolffish. Fish genotypic hybrid identification for field studies is frequently used (Metcalf et al 2008;Papousek et al 2008). Our results, based on the utilisation of seven loci (i.e.…”

Section: Discussionmentioning

confidence: 99%