Timing and Location of Spawning by Nonnative Wild Rainbow Trout and Native Cutthroat Trout in the South Fork Snake River, Idaho, with Implications for Hybridization

Henderson, Richard C.; Kershner, Jeffrey L.; Toline, C. Anna

doi:10.1577/1548-8675(2000)020<0584:talosb>2.3.co;2

Cited by 56 publications

(99 citation statements)

References 17 publications

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“…In the case of invasive species where contact between species often results in hybridization and introgression due to absent or incompletely evolved reproductive isolation mechanisms (Rhymer and Simberloff 1996), mating is often symmetric. The lack of ecological segregation during spawning between indigenous cutthroat trout and non-indigenous, introduced RBT may explain the symmetric mating pattern reported by many studies (Henderson et al 2000;Rubidge et al 2001;Rubidge and Taylor 2004) including this study. The number of hybrid individuals in the SFSR watershed with RBT versus YCT mtDNA was reflective of the relative proportion of each parental species, suggesting symmetrical hybridization.…”

Section: Levels Of Introgression Hybrid Classes and Yct-genotype Pomentioning

confidence: 53%

“…Thus, RBT and YCT evolved in allopatry, and selection for reproductive isolation has likely not been sufficient to prevent interbreeding in the short period since they have been forced into secondary contact as a result of stocking of RBT. Lack of reproductive isolation, coupled with the close phylogenetic relationship between the two species (RBT and YCT are sister taxa; Behnke 1992) and an overlap in spawning seasons (Varley and Gresswell 1988;Henderson et al 2000), has resulted in the two species readily hybridizing and forming fertile hybrid offspring in regions of secondary contact (Loudenslager and Gall 1980;Loudenslager 1981;Kruegar and May 1991). As a popular game fish, RBT have been extensively stocked by fisheries managers into watersheds far outside their native distribution, thereby exacerbating the potential for widespread displacement of native cutthroat trout by RBT.…”

Section: Introductionmentioning

confidence: 99%

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Geographic patterns of introgressive hybridization between native Yellowstone cutthroat trout (Oncorhynchus clarkii bouvieri) and introduced rainbow trout (O. mykiss) in the South Fork of the Snake River watershed, Idaho

et al. 2007

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Throughout its native range, the Yellowstone cutthroat trout (YCT), Oncorhynchus clarkii bouvieri, is declining dramatically in both abundance and distribution as a result of introgression with introduced rainbow trout (RBT), O. mykiss. We sampled over 1,200 trout from the South Fork of the Snake River (SFSR) watershed, in southeastern Idaho and western Wyoming, and measured the extent of introgression of RBT genes into native gene pools of YCT using seven species-specific, co-dominant nuclear genetic markers. We also used mitochondrial DNA (mtDNA) haplotype differences between the two parental trout species to determine the directionality of the hybridization. We found low levels of RBT introgression (only 7% of sampled individuals had one or more RBT alleles) into YCT gene pools, with the majority of hybrids (78%) occurring in mainstem localities of the SFSR and in lower elevation reaches of certain tributaries. Hybridization was bidirectional with respect to mtDNA haplotype, but the majority of hybrids (75%) had YCT maternal haplotypes, indicative of the greater proportion (90%) of YCT-genotypes in the SFSR watershed. The primary factor influencing the geographic distribution of RBT introgressed individuals was fluvial distance from localities of stocking origin. To a lesser extent, elevation, also influenced the distribution of hybrid genotypes, with several entire tributaries and all upper elevation reaches within tributaries harboring only YCT-genotypes. Important management implications of the study suggest targeting particular tributaries and upper reaches within tributaries for YCT protection and exclusion of RBT hybrid colonization.

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Section: Levels Of Introgression Hybrid Classes and Yct-genotype Pomentioning

confidence: 53%

Section: Introductionmentioning

confidence: 99%

Geographic patterns of introgressive hybridization between native Yellowstone cutthroat trout (Oncorhynchus clarkii bouvieri) and introduced rainbow trout (O. mykiss) in the South Fork of the Snake River watershed, Idaho

et al. 2007

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“…Rainbow and hybrid trout in the study reach do not differ significantly from each other in spawning behaviour and spawn in mid-May, on average, in the river and lower reaches of tributaries [30]. These characteristics differ significantly from those of cutthroat trout, which spawn in early June, on average, and often in upper reaches of tributaries [30].…”

Section: Study Area and Research Objectivesmentioning

confidence: 66%

“…These characteristics differ significantly from those of cutthroat trout, which spawn in early June, on average, and often in upper reaches of tributaries [30]. Tests of competition show no significant differences in competitive ability and aggression between rainbow and hybrid trout but significantly greater aggression and competitive ability in rainbow and hybrid trout relative to Yellowstone cutthroat trout [70,71].…”

Section: Study Area and Research Objectivesmentioning

confidence: 80%

“…Spatial and temporal segregation of spawning can limit the extent of hybridization between rainbow/hybrid trout and cutthroat trout [13,30], but cutthroat trout continue to decline in some streams even under such reproductive segregation [38]. Thus, mechanisms other than hybridization may contribute to the displacement of cutthroat trout by introduced rainbow trout.…”

Section: Introductionmentioning

confidence: 99%

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Modelling competition and hybridization between native cutthroat trout and nonnative rainbow and hybrid trout

Kirk

Battle

Schrader

2009

Journal of Biological Dynamics

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Native salmonid fish have been displaced worldwide by nonnatives through hybridization, competition, and predation, but the dynamics of these factors are poorly understood. We apply stochastic Lotka-Volterra models to the displacement of cutthroat trout by rainbow/hybrid trout in the Snake River, Idaho, USA. Cutthroat trout are susceptible to hybridization in the river but are reproductively isolated in tributaries via removal of migratory rainbow/hybrid spawners at weirs. Based on information-theoretic analysis, population data provide evidence that hybridization was the primary mechanism for cutthroat trout displacement in the first 17 years of the invasion. However, under some parameter values, the data provide evidence for a model in which interaction occurs among fish from both river and tributary subpopulations. This situation is likely to occur when tributary-spawned cutthroat trout out-migrate to the river as fry. The resulting competition with rainbow/hybrid trout can result in the extinction of cutthroat trout even when reproductive segregation is maintained.

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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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Timing and Location of Spawning by Nonnative Wild Rainbow Trout and Native Cutthroat Trout in the South Fork Snake River, Idaho, with Implications for Hybridization

Cited by 56 publications

References 17 publications

Geographic patterns of introgressive hybridization between native Yellowstone cutthroat trout (Oncorhynchus clarkii bouvieri) and introduced rainbow trout (O. mykiss) in the South Fork of the Snake River watershed, Idaho

Geographic patterns of introgressive hybridization between native Yellowstone cutthroat trout (Oncorhynchus clarkii bouvieri) and introduced rainbow trout (O. mykiss) in the South Fork of the Snake River watershed, Idaho

Modelling competition and hybridization between native cutthroat trout and nonnative rainbow and hybrid trout

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

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