Genetic Variation in Time and Space: Microsatellite Analysis of Extinct and Extant Populations of Atlantic Salmon

Nielsen, Einar Eg; Hansen, Michael Møller; Loeschcke, Volker

doi:10.1111/j.1558-5646.1999.tb05351.x

Cited by 108 publications

(90 citation statements)

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“…During the last decade, however, the empirical evidence for these relationships seems somewhat conflictive. That is, there is good evidence that small population size decreases genetic variation, and temporal studies on genetic diversity have demonstrated this, particularly at the molecular level (e.g., Bouzat et al 1998;Hadly et al 1998;Nielsen et al 1999). However, results on population bottlenecks, quantitative genetic variation and inbreeding depression do not necessarily show consistent trends.…”

Section: The Detrimental Paradigm Of Inbreeding Depressionmentioning

confidence: 96%

Conservation genetics of population bottlenecks: the role of chance, selection, and history

2010

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Conservation genetics studies of populations bottlenecks are commonly framed under the detrimental paradigm of inbreeding depression. This conceptual paradigm presupposes a direct and unambiguous relationship between population size, genetic diversity, fitness, and extinction. Here, I review a series of studies that emphasize the role of chance, selection, and history in determining the genetic consequences of population bottlenecks. The variable responses of bottlenecks to fitness, phenotypic variation, and heritable variation emphasize the necessity to explore the relationship between molecular genetic diversity, fitness, adaptive genetic diversity, and extinction beyond the detrimental paradigm of inbreeding depression. Implications for conservation and management are presented as guidelines and testable predictions regarding the potential effects of bottlenecks on population viability and extinction.

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Section: The Detrimental Paradigm Of Inbreeding Depressionmentioning

confidence: 96%

Conservation genetics of population bottlenecks: the role of chance, selection, and history

2010

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“…Historical collections of fish scales and fish otoliths have been made, generally for use in ageing individuals, but in more recent times, protocols have been developed for their use in molecular genetic work (Hutchinson et al 1999;Nielsen et al 1999a), for example in the amplification of mtDNA and microsatellites (Nielsen et al 1999b). Historic collections (especially of fish scales) are particularly useful for the investigation of longterm genetic processes and perturbations to genetic structure.…”

Section: Introductionmentioning

confidence: 99%

Stocking may increase mitochondrial DNA diversity but fails to halt the decline of endangered Atlantic salmon populations

et al. 2007

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Over the last 50 years, Spanish Atlantic salmon (Salmo salar) populations have been in decline. In order to bolster these populations, rivers were stocked with fish of northern European origin during the period 1974-1996, probably also introducing the furunculosis-inducing pathogen, Aeromonas salmonicida. Here we assess the relative importance of processes influencing mitochondrial (mt)DNA variability in these populations from 1948 to 2002. Genetic material collected over this period from four rivers in northern Spain (Cantabria) was used to detect variability at the mtDNA ND1 gene. Before stocking, a single haplotype was found at high frequency (0.980). Following stocking, haplotype diversity (h) increased in all rivers (mean h before stocking was 0.041, and 0.245 afterwards). These increases were due principally to the dramatic increase in frequency of a previously very low frequency haplotype, reported at higher frequencies in northern European populations proximate to those used to stock Cantabrian rivers. Genetic structuring increased after stocking: among-river differentiation was low before stocking (1950s/1960s F ST = -0.00296-0.00284), increasing considerably at the height of stocking (1980s F ST = 0.18932) and decreasing post-stocking (1990s/2002 F ST = 0.04934-0.03852). Gene flow from stocked fish therefore seems to have had a substantial role in increasing mtDNA variability. Additionally, we found significant differentiation between individuals that had probably died from infectious disease and apparently healthy, angled fish, suggesting a possible role for pathogen-driven selection of mtDNA variation. Our results suggest that stocking with non-native fish may increase genetic diversity in the short term, but may not reverse population declines.

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“…A suitable mitochondrial marker to carry out this task is ND1, where considerable differentiation has been reported among European salmon populations (Verspoor et al 1999;Nilsson et al 2001;Consuegra et al 2002;Asplund et al 2004). In addition, it is often possible to compare the genetic variation at ND1 before and after introductions in order to detect potential changes when old scale collections are available (Nielsen et al 1999;Martínez et al 2001;Hansen 2002;Heath et al 2002;Ostergaard et al 2003).…”

Section: Introductionmentioning

confidence: 99%

Introgression and genetic structure in northern Spanish Atlantic salmon (Salmo salar L.) populations according to mtDNA data

2007

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We have used PCR-RFLP analysis to screen ancestral and modern genetic variation of the mitochondrial ND1 region at eight Atlantic salmon rivers in northern Spain. Using old scales, we show that genetic variation in NW Spanish salmon populations has not changed significantly during the past 50 years. Comparing our data with that from the literature we can conclude that, in general, modern salmon populations from NW Spain are distinct from putative northern European donor populations. Taken together, these observations suggest that, despite the nonnative introductions carried out during 1970-1993, introgression of northern European mitochondrial genomes in NW Spanish salmon populations has been generally low. Different results were obtained for populations in NE Spain and southern France, where rivers Nansa, Asón, Bidasoa and Nive presented a high frequency of haplotypes characteristic of northern European rivers that reflect introgression. We show that the levels of introgression are correlated with the foreign stocking intensity. Thus, the rivers that were more intensely stocked are more similar to northern European salmon rivers. We also observed an East-West cline in the levels of foreign introductions and introgression. In addition, we provide the first description of the overall genetic structure of Atlantic salmon populations in southern Europe. We have observed evidences of genetic differentiation among populations and isolation by distance as a consequence of salmon homing behaviour. The results obtained do not call for changes in introduction policies in Spain, currently based on the use of native stocks.

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Genetic Variation in Time and Space: Microsatellite Analysis of Extinct and Extant Populations of Atlantic Salmon

Cited by 108 publications

References 50 publications

Conservation genetics of population bottlenecks: the role of chance, selection, and history

Conservation genetics of population bottlenecks: the role of chance, selection, and history

Stocking may increase mitochondrial DNA diversity but fails to halt the decline of endangered Atlantic salmon populations

Introgression and genetic structure in northern Spanish Atlantic salmon (Salmo salar L.) populations according to mtDNA data

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