Microsatellites reveal fine-scale genetic structure in stream-living brown trout

Carlsson, Jens

doi:10.1006/jfbi.1999.1123

Cited by 65 publications

(99 citation statements)

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“…These populations displayed a very low genetic diversity and were genetically the most distinct for the other brown trout populations. Our results confirm that migration barriers have a profound effect on the local population structure and genetic diversity of riverine species as previously has been shown (Carlsson et al 1999;Meldgaard et al 2003). However, in the case of the Belgian brown trout these barriers apparently sheltered indigenous gene pools from the homogenizing effects of stocking.…”

Section: The Impact Of Stocking and Migration Barrierssupporting

confidence: 88%

Migration barriers protect indigenous brown trout (Salmo trutta) populations from introgression with stocked hatchery fish

et al. 2005

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Brown trout populations in the Belgian rivers Scheldt and Meuse have been intensively stocked in the past decades, often with material of uncertain origin. Moreover, the species' habitat has become increasingly fragmented, preventing gene flow between neighboring populations. We assessed how this impacted genetic diversity and population structure by analyzing 12 wild populations (total n ¼ 309) and seven hatchery stocks (n ¼ 200) at the mitochondrial control region with SSCP and at 27 RAPD loci. Historical records indicate that brown trout from distant locations have been used to supplement hatchery stocks; nevertheless we detected non-Atlantic mitochondrial genomes in only one population of the Scheldt basin and in one hatchery. In general, the hatchery samples displayed a higher genetic diversity and differentiated less among each other (global F ST(mtDNA) ¼ 0.311/F ST(RAPD) ¼ 0.029) compared to the wild populations (global F ST(mtDNA) ¼ 0.477/F ST(RAPD) ¼ 0.204). This is due to frequent exchanges between hatcheries and regular supplementation from several indigenous populations. Gene pools present in most downstream sections from tributaries of the Meuse were similar to each other and to the hatchery samples, despite the presence of migration barriers. Assignment analyses indicated that the contribution of hatchery material to the upstream parts was limited or even completely absent in populations separated by a physical barrier. Intensive stocking and exchange between hatcheries has homogenized the downstream sections of the Meuse River, whereas the migration barriers preserved the indigenous upstream populations. As such, uncontrolled removal of barriers might result in an irreversible loss of the remnant indigenous gene pools.

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Section: The Impact Of Stocking and Migration Barrierssupporting

confidence: 88%

Migration barriers protect indigenous brown trout (Salmo trutta) populations from introgression with stocked hatchery fish

et al. 2005

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“…Ryman 1983;Carlsson et al 1999;Ruzzante et al 2001). However, the importance of taking temporal variation within populations into account when investigating population structure has only recently been appreciated.…”

Section: Introductionmentioning

confidence: 99%

Spatial and temporal genetic differentiation and effective population size of brown trout (Salmo trutta, L.) in small Danish rivers

Jensen

Hansen²,

Carlsson

et al. 2005

Conserv Genet

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The spatial and temporal genetic structure of brown trout populations from three small tributaries of Lake Hald, Denmark, was studied using analysis of variation at eight microsatellite loci. From two of the populations temporal samples were available, separated by up to 13 years (3.7 generations). Significant genetic differentiation was observed among all samples, however, hierarchical analysis of molecular variance (AMOVA) showed that differentiation among populations accounted for a non-significant amount of the genetic differentiation, whereas differentiation among temporal samples within populations was highly significant (0.0244, P<0.001). Estimates of effective population size (N e ) using a maximum-likelihood based implementation of the temporal method, yielded small values (N e ranging from 33 to 79). When a model was applied that allows for migration among populations, N e estimates were even lower (24-54), and migration rates were suggested to be high (0.13-0.36). All samples displayed a clear signal of a recent bottleneck, probably stemming from a period of unfavourable conditions due to organic pollution in the 1970-1980's. By comparison to other estimates of N e in brown trout, Lake Hald trout represent a system of small populations linked by extensive gene flow, whereas other populations in larger rivers exhibit much higher N e values and experience lower levels of immigration. We suggest that management considerations for systems like Lake Hald brown trout should focus both on a regional scale and at the level of individual populations, as the future persistence of populations depends both on maintaining individual populations and ensuring sufficient migration links among these populations.

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“…Such a sampling scheme is important because stream-dwelling salmoninds are known to exhibit fine-scale genetic structure even over a few kilometers (Carlsson et al 1999;Hudy et al 2010;Spruell et al 1999) and spatially limited sampling might result in inaccurate understanding of reproduction and spatial structure. For example, sampling from selected stream reaches might contain a high proportion of related individuals (Hansen et al 1997), and it would bias the watershed-scale estimate of N e .…”

Section: Introductionmentioning

confidence: 99%

Sibship reconstruction for inferring mating systems, dispersal and effective population size in headwater brook trout (Salvelinus fontinalis) populations

2010

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Brook trout Salvelinus fontinalis populations have declined in much of the native range in eastern North America and populations are typically relegated to small headwater streams in Connecticut, USA. We used sibship reconstruction to infer mating systems, dispersal and effective population size of resident (non-anadromous) brook trout in two headwater stream channel networks in Connecticut. Brook trout were captured via backpack electrofishing using spatially continuous sampling in the two headwaters (channel network lengths of 4.4 and 7.7 km). Eight microsatellite loci were genotyped in a total of 740 individuals (80-140 mm) subsampled in a stratified random design from all 50 m-reaches in which trout were captured. Sibship reconstruction indicated that males and females were both mostly polygamous although single pair matings were also inferred. Breeder sex ratio was inferred to be nearly 1:1. Few large-sized fullsib families ([3 individuals) were inferred and the majority of individuals were inferred to have no fullsibs among those fish genotyped (family size = 1). The median stream channel distance between pairs of individuals belonging to the same large-sized fullsib families ([3 individuals) was 100 m (range: 0-1,850 m) and 250 m (range: 0-2,350 m) in the two study sites, indicating limited dispersal at least for the size class of individuals analyzed. Using a sibship assignment method, the effective population size for the two streams was estimated at 91 (95%CI: 67-123) and 210 (95%CI: 172-259), corresponding to the ratio of effectiveto-census population size of 0.06 and 0.12, respectively. Both-sex polygamy, low variation in reproductive success, and a balanced sex ratio may help maintain genetic diversity of brook trout populations with small breeder sizes persisting in headwater channel networks.

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Microsatellites reveal fine-scale genetic structure in stream-living brown trout

Cited by 65 publications

References 0 publications

Migration barriers protect indigenous brown trout (Salmo trutta) populations from introgression with stocked hatchery fish

Migration barriers protect indigenous brown trout (Salmo trutta) populations from introgression with stocked hatchery fish

Spatial and temporal genetic differentiation and effective population size of brown trout (Salmo trutta, L.) in small Danish rivers

Sibship reconstruction for inferring mating systems, dispersal and effective population size in headwater brook trout (Salvelinus fontinalis) populations

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