Relationship between cardiac performance and environment across populations of Atlantic salmon (Salmo salar): a common garden experiment implicates local adaptation

Adaptive responses to environmental heterogeneity may vary among populations. Genetic variability in reaction norms might account for population differences in the ability to respond to environmental change and may reflect local adaptation. Reaction norms for early life history traits were compared among three population crosses of Atlantic salmon ( Salmo salar ). Two comprised second-generation backcrosses introgressed with either farmed or wild genes; the third comprised individuals from a second-generation, pure wild cross. Using a common-garden experimental protocol, each cross was exposed to three temperature regimes. Plasticity in embryonic development, growth, survival, and body size was measured from fertilization up to 24 weeks of exogenous feeding. Reaction norms differed markedly among crosses, irrespective of whether individuals interbred with those whose genes originated from another wild population or from a cultured population. We find that introgression involving individuals with comparatively few genetic differences can change reaction norms. If plasticity represents an adaptive response to local environments, then changes to reaction norms resulting from interbreeding between populations are unlikely to have a beneficial effect on fitness.

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Effects of acidic pH on wild, farmed, and F1 hybrid Atlantic salmon (Salmo salar) parr

Canadian Journal of Fisheries and Aquatic Sciences ◽

10.1139/cjfas-2017-0006 ◽

2018 ◽

Vol 75 (1) ◽

pp. 116-120

Author(s):

Lynn Lush ◽

Isabel Costa ◽

Kimberly Marshall ◽

Juan Carlos Pérez-Casanova ◽

Rénald Belley ◽

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Keyword(s):

Atlantic Salmon ◽

Salmo Salar ◽

Common Garden ◽

F1 Hybrids ◽

Acidic Ph ◽

F1 Hybrid ◽

Atlantic Salmon Salmo Salar ◽

In The Wild ◽

Acidic Waters ◽

Farmed Atlantic Salmon

Farmed escapees have the potential to introduce novel genes to wild salmon and alter locally adapted populations. We tested whether the acidic conditions found in rivers on Newfoundland’s south coast might differentially impact offspring of farmed Atlantic salmon (Salmo salar) in comparison to wild populations. We performed crosses with wild and farmed parents to obtain wild (W♂ × W♀), farmed (F♂ × F♀), and F1 hybrid (W♂ × F♀, F♂ × W♀) parr and conducted a common garden experiment at neutral or acidic pH. No differences were observed between pure wild crosses and F1 hybrids, suggesting that acidic waters do not differentially affect survival, growth, condition factor, and Na+/K+-ATPase activity of F1 hybrids. Trends in mortality show that pure farmed parr had lower survival than pure wild and F1 hybrids in low pH. Considering that production of F1 hybrids rather than pure farmed offspring is the most likely outcome in the wild, pure farmed parr survival may have little bearing on the prediction of genetic risks of farmed–wild interactions. There is no evidence to indicate that the survival of the F1 generation in acidic waters acts as a potential barrier against introgression.

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