Temporal and spatial segregation of spawning by wild and farm‐reared brown trout,<i>Salmo trutta</i>L., in the River Avon, Wiltshire, UK

Shields, Barbara A.; Stubbing, D. N.; Summers, D. W.; Giles, N.

doi:10.1111/j.1365-2400.2004.00429.x

Cited by 6 publications

(5 citation statements)

References 8 publications

(7 reference statements)

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“…Reproductive isolation through isolation by time (IBT) has recently attracted considerable interest (Hendry & Day 2005). IBT may be common in hatchery-wild salmonid interactions, as genetic components of spawning time differences have been demonstrated in at least one species (Sakamoto et al 1999), hatchery managers often select broodstock for early spawning (Hansen et al 2006) and temporal segregation of spawning has been observed in sympatric wild and hatchery strain salmonids (Shields et al 2005). We hypothesize that IBT has rescued a small proportion of the indigenous SKJ population from full introgression.…”

Section: Discussionmentioning

confidence: 99%

Admixture analysis of stocked brown trout populations using mapped microsatellite DNA markers: indigenous trout persist in introgressed populations

Hansen

Mensberg

2009

Biol. Lett.

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Admixture between wild and captive populations is an increasing concern in conservation biology. Understanding the extent of admixture and the processes involved requires identification of admixed and non-admixed individuals. This can be achieved by statistical methods employing Bayesian clustering, but resolution is low if genetic differentiation is weak. Here, we analyse stocked brown trout populations represented by historical (1943 -1956) and contemporary (2000s) samples, where genetic differentiation between wild populations and stocked trout is weak (pairwise F ST of 0.047 and 0.053). By analysing a high number of microsatellite DNA markers (50) and making use of linkage map information, we achieve clear identification of admixed and non-admixed trout. Moreover, despite strong population-level admixture by hatchery strain trout in one of the populations (70.8%), nonadmixed individuals nevertheless persist (7 out of 53 individuals). These remnants of the indigenous population are characterized by later spawning time than the majority of the admixed individuals. We hypothesize that isolation by time mediated by spawning time differences between wild and hatchery strain trout is a major factor rescuing a part of the indigenous population from introgression.

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Section: Discussionmentioning

confidence: 99%

Admixture analysis of stocked brown trout populations using mapped microsatellite DNA markers: indigenous trout persist in introgressed populations

Hansen

Mensberg

2009

Biol. Lett.

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“…There are, however, factors that could delay introgression of exogenous genes into indigenous gene pools. In the context of salmonid fish, domesticated fish could exhibit different peak spawning times, habitat preferences and geographical distributions within rivers compared with wild populations (Shields et al . 2005), thereby leading to partial temporal and spatial reproductive isolation.…”

Section: Introductionmentioning

confidence: 99%

Genetic restoration of a stocked brown trout Salmo trutta population using microsatellite DNA analysis of historical and contemporary samples

Hansen¹,

Bekkevold²,

Jensen

et al. 2006

Journal of Applied Ecology

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Summary1. Gene flow from domesticated to wild populations is a major threat to wild salmonid fish. However, few studies have addressed how populations could be restored after admixture has occurred. We analysed the prospects for restoring the previously intensively stocked brown trout population of the Skjern River, Denmark, by identifying remaining nonadmixed individuals to be used for supportive breeding. 2. We analysed microsatellite DNA markers in historical (1940 -50s) and contemporary (1992)(1993)(1994)(1995)(1996)(1997)(1998)(1999)(2000)(2001)(2002)(2003)(2004) samples from the Skjern River system, from the strain of domesticated trout previously used for stocking, and from the neighbouring Storå River. We analysed admixture proportions to estimate the genetic contribution by domesticated trout. We identified non-admixed trout using assignment tests, and further analysed the possible sources of indigenous trout by estimating contemporary migration among populations. 3. Genetic differentiation between the historical Storå and Skjern river populations was low ( θ ST = 0·004), suggesting considerable gene flow in the past. The contemporary Skjern and Storå river populations and a supportive breeding brood stock were strongly admixed, but some non-admixed individuals nevertheless remained in the wild-caught samples. In addition, two resident populations in isolated tributaries were found to be indigenous. The indigenous anadromous individuals from the Skjern River were unlikely to have been recruited from either the isolated tributary populations or the neighbouring Storå River and were presumably derived from unidentified spawning sites in the river system. 4. All but one non-admixed anadromous Skjern River trout were females, which we ascribed to sampling bias. Moreover, all non-admixed fish were late-spawning (JanuaryFebruary) whereas the majority of all trout caught for the study were ripe by NovemberDecember. The difference in spawning time could be an important factor delaying complete admixture of domesticated and indigenous trout. 5. Synthesis and applications. This study demonstrates the feasibility of restoring populations that have been admixed with exogenous individuals, by identifying non-admixed individuals using genetic markers. However, the results also highlight the problem that numbers of identified non-admixed individuals may be small, necessitating identification of nearby, closely related populations that can be incorporated into breeding programmes.

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“…Moreover, the similarity between most repeat-spawning dates of marked fish indicates that an underlying, innate mechanism influences migration timing (Shields et al, 2005). It has been demonstrated that the time of spawning in salmonids is highly heritable (Stefanik and Sandheirich, 1999).…”

Section: Genetic Variation and Population Structuring On Migratory Frmentioning

confidence: 99%

Contribution of conservation genetics in assessing neotropical freshwater fish biodiversity

Piorski¹,

Sanches

Costa

et al. 2008

Braz. J. Biol.

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Human activities have a considerable impact on hydrographic systems and fish fauna. The present review on conservation genetics of neotropical freshwater fish reveals that DNA analyses have been promoting increased knowledge on the genetic structure of fish species and their response to environmental changes. This knowledge is fundamental to the management of wild fish populations and the establishment of Evolutionary Significant Units capable of conserving genetic integrity. While population structuring can occur even in long-distance migratory fish, isolated populations can show reduced genetic variation and be at greater risk of extinction. Phylogeography and phylogeny have been powerful tools in understanding the evolution of fish populations, species and communities in distinct neotropic environments. Captive fish can be used to introduce new individuals and genes into the wild and their benefits and disadvantages can be monitored through genetic analysis. Understanding how fish biodiversity in neotropical freshwaters is generated and maintained is highly important, as these habitats are transformed by human development and fish communities are increasingly exploited as food sources to sustain a growing human population.Keywords: molecular genetics, fish population, biology conservation. Contribuição da Genética da Conservação para o conhecimento da biodiversidade dos peixes de água doce neotropicais ResumoAtividades humanas têm um grande impacto sobre os sistemas hidrográficos e a fauna de peixes. A presente revisão em genética da conservação dos peixes de água doce neotropicais revela que as análises de DNA têm promovido um crescimento no conhecimento da estrutura genética das espécies e suas respostas às alterações ambientais. Este conhecimento é fundamental para o manejo das populações de peixes nativos e para o estabelecimento de Unidades Evolutivas Significantes capazes de conservar a integridade genética dessas populações. Enquanto o fenômeno de estruturação de populações pode ocorrer mesmo em peixes migradores de longas distâncias, populações isoladas podem mostrar reduzida variação genética e apresentar grande risco de extinção. Em adição, a filogeografia e a filogenia têm dado importantes contribuições para o entendimento da evolução das populações, espécies e comunidades de peixes em distintos ambientes neotropicais. Populações de cativeiro podem ser utilizadas como fonte de introdução de novos indivíduos e genes no ambiente natural e seus benefícios e desvantagens podem ser monitorados por meio de análises genéticas. É altamente importante, portanto, entender como é gerada e mantida a biodiversidade de peixes de água doce neotropicais, uma vez que os habitats são transformados pelo desenvolvimento humano e as comunidades de peixes têm sido intensamente exploradas como alimento de sustentação desse crescimento das populações humanas.Palavras-chave: genética molecular, populações de peixes, conservação biológica.

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Temporal and spatial segregation of spawning by wild and farm‐reared brown trout,Salmo truttaL., in the River Avon, Wiltshire, UK

Cited by 6 publications

References 8 publications

Admixture analysis of stocked brown trout populations using mapped microsatellite DNA markers: indigenous trout persist in introgressed populations

Admixture analysis of stocked brown trout populations using mapped microsatellite DNA markers: indigenous trout persist in introgressed populations

Genetic restoration of a stocked brown trout Salmo trutta population using microsatellite DNA analysis of historical and contemporary samples

Contribution of conservation genetics in assessing neotropical freshwater fish biodiversity

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