Genetic rescue insights from population- and family-level hybridization effects in brook trout

Wells, Zachery R. R.; Bernos, Thaïs A.; Yates, Matthew C.; Fraser, Dylan J.

doi:10.1007/s10592-019-01179-z

Cited by 15 publications

(21 citation statements)

References 74 publications

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“…Indeed, increasing empirical evidence suggests that recently fragmented populations with reduced population sizes may receive demographic benefits from gene flow beyond the addition of immigrant individuals through genetic rescue (Frankham, 2015). However, most empirical studies conducted on wild populations to date are incomplete because of the difficulty of rigorously assessing the impact of detected genotype–environment or genotype–phenotype associations on individual fitness (but see Wells, Bernos, Yates, & Fraser, 2019). As such, our study adds to the increasing realization that in a context of a rapidly changing environment, the risk of maladaptation must be considered in planning conservation strategies.…”

Section: Resultsmentioning

confidence: 99%

“…However, most empirical studies conducted on wild populations to date are incomplete because of the difficulty of rigorously assessing the impact of detected genotype-environment or genotype-phenotype associations on individual fitness (but see Wells, Bernos, Yates, & Fraser, 2019). As such, our study adds to the increasing realization that in a context of a rapidly changing environment, the risk of maladaptation must be considered in planning conservation strategies.…”

Section: Con Clus Ionmentioning

confidence: 99%

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Adaptive and maladaptive genetic diversity in small populations: Insights from the Brook Charr (Salvelinus fontinalis) case study

et al. 2020

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Investigating the relative importance of neutral versus selective processes governing the accumulation of genetic variants is a key goal in both evolutionary and conservation biology. This is particularly true in the context of small populations, where genetic drift can counteract the effect of selection. Using Brook Charr (Salvelinus fontinalis) from Québec, Canada, as a case study, we investigated the importance of demographic versus selective processes governing the accumulation of both adaptive and maladaptive mutations in closed versus open and connected populations to assess gene flow effect. This was achieved by using 14,779 high‐quality filtered SNPs genotyped among 1,416 fish representing 50 populations from three life history types: lacustrine (closed populations), riverine and anadromous (connected populations). Using the PROVEAN algorithm, we observed a considerable accumulation of putative deleterious mutations across populations. The absence of correlation between the occurrence of putatively beneficial or deleterious mutations and local recombination rate supports the hypothesis that genetic drift might be the main driver of the accumulation of such variants. However, despite a lower genetic diversity observed in lacustrine than in riverine or anadromous populations, lacustrine populations do not exhibit more deleterious mutations than the two other history types, suggesting that the negative effect of genetic drift in lacustrine populations may be mitigated by that of relaxed purifying selection. Moreover, we also identified genomic regions associated with anadromy, as well as an overrepresentation of transposable elements associated with variation in environmental variables, thus supporting the importance of transposable elements in adaptation.

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Section: Resultsmentioning

confidence: 99%

Section: Con Clus Ionmentioning

confidence: 99%

Adaptive and maladaptive genetic diversity in small populations: Insights from the Brook Charr (Salvelinus fontinalis) case study

et al. 2020

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“…Genetic rescue via hybridization with another salmon population is one potential and possibly necessary method to conserve this unique population. Because the risk of outbreeding depression grows with genetic distance, careful evaluation and more studies on the risks and benefits associated with outbreeding in threatened salmonid populations are needed (Edmands 2007;Burridge 2019;Wells et al 2019).…”

Section: Introductionmentioning

confidence: 99%

Sperm motility and offspring pre- and posthatching survival in hybridization crosses among a landlocked and two anadromous Atlantic salmon populations: implications for conservation

Eronen

Kekäläinen

Piironen

et al. 2021

Can. J. Fish. Aquat. Sci.

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The landlocked salmon (Salmo salar m. sebago) endemic to Lake Saimaa, Finland, is critically endangered and severely threatened by low genetic diversity and inbreeding. To explore the possibility of increasing the genetic diversity of threatened salmon populations by controlled hybridization (genetic rescue), we studied sperm motility and offspring pre- and post-hatching survival in hybridization crosses of landlocked salmon with two geographically close anadromous salmon populations (Rivers Neva and Tornio) relative to the pure-bred populations. While some degree of gametic incompatibility between landlocked and Tornio salmon cannot be ruled out, there were no indications of outbreeding depression in survival traits in these first-generation hybridizations. Instead, pre-hatching survival of landlocked salmon eggs fertilized with Neva salmon sperm and post-hatching survival of anadromous salmon eggs fertilized with landlocked salmon sperm were higher than in pure-bred landlocked salmon. These differences might imply genetic rescue effects (hybrid vigor), although there were also strong maternal effects involved. Our results on early viability point to the possibility of applying genetic rescue to the landlocked salmon population by hybridization with an anadromous population.

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“…Several authors have argued against a mixing strategy on the grounds that hybridisation between genetically distinct stocks can result in offspring of lowered fitness due to outbreeding depression through loss of local adaptation or the disruption of co‐adapted gene pools in the F 2 and later generations (Huff et al, ). However, it is likely that concerns about outbreeding depression have been overstated as several studies have indicated that, although outbreeding depression can occur in early generations, selection can quickly overcome this and result in hybrid superiority in later generations (Houde et al, ; Whiteley et al, ; Wells et al, ). As demonstrated in Loch Fleet, a mixing approach is likely to be the best option for population re‐establishment, except where there is clear evidence of a donor population with adaptive qualities appropriate to the environmental conditions as is the case with Loch Grannoch.…”

Section: Discussionmentioning

confidence: 99%

Impacts of acidification on brown trout Salmo trutta populations and the contribution of stocking to population recovery and genetic diversity

Prodöhl

Ferguson

Bradley

et al. 2019

Journal of Fish Biology

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Anthropogenic acidification in SW‐Scotland, from the early 19th Century onwards, led to the extinction of several loch (lake) brown trout (Salmo trutta) populations and substantial reductions in numbers in many others. Higher altitude populations with no stocking influence, which are isolated above natural and artificial barriers and subjected to the greatest effect of acidification, exhibited the least intrapopulation genetic diversity (34% of the allelic richness of the populations accessible to anadromous S. trutta). These, however, were characterised by the greatest interpopulation divergence (highest pairwise D EST 0.61 and F ST 0.53 in contemporary samples) based on 16 microsatellite loci and are among the most differentiated S. trutta populations in NW‐Europe. Five lochs above impassable waterfalls, where S. trutta were thought to be extinct, are documented as having been stocked in the late 1980s or 1990s. All five lochs now support self‐sustaining S. trutta populations; three as a direct result of restoration stocking and two adjoining lochs largely arising from a small remnant wild population in one, but with some stocking input. The genetically unique Loch Grannoch S. trutta, which has been shown to have a heritable increased tolerance to acid conditions, was successfully used as a donor stock to restore populations in two acidic lochs. Loch Fleet S. trutta, which were re‐established from four separate donor sources in the late 1980s, showed differential contribution from these ancestors and a higher genetic diversity than all 17 natural loch populations examined in the area. Genetically distinct inlet and outlet spawning S. trutta populations were found in this loch. Three genetically distinct sympatric populations of S. trutta were identified in Loch Grannoch, most likely representing recruitment from the three main spawning rivers. A distinct genetic signature of Loch Leven S. trutta, the progenitor of many Scottish farm strains, facilitated detection of stocking with these strains. One artificially created loch was shown to have a population genetically very similar to Loch Leven S. trutta. In spite of recorded historical supplemental stocking with Loch Leven derived farm strains, much of the indigenous S. trutta genetic diversity in the area remains intact, aside from the effects of acidification induced bottlenecks. Overall genetic diversity and extant populations have been increased by allochthonous stocking.

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Genetic rescue insights from population- and family-level hybridization effects in brook trout

Cited by 15 publications

References 74 publications

Adaptive and maladaptive genetic diversity in small populations: Insights from the Brook Charr (Salvelinus fontinalis) case study

Adaptive and maladaptive genetic diversity in small populations: Insights from the Brook Charr (Salvelinus fontinalis) case study

Sperm motility and offspring pre- and posthatching survival in hybridization crosses among a landlocked and two anadromous Atlantic salmon populations: implications for conservation

Impacts of acidification on brown trout Salmo trutta populations and the contribution of stocking to population recovery and genetic diversity

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