An extensive common‐garden study with domesticated and wild Atlantic salmon in the wild reveals impact on smolt production and shifts in fitness traits

The conditions encountered by Atlantic salmon, Salmo salar L., in aquaculture are markedly different from the natural environment. Typically, farmed salmon experience much higher densities than wild individuals, and may therefore have adapted to living in high densities. Previous studies have demonstrated that farmed salmon typically outgrow wild salmon by large ratios in the hatchery, but these differences are much less pronounced in the wild. Such divergence in growth may be explained partly by the offspring of wild salmon experiencing higher stress and thus lower growth when compared under high-density farming conditions. Here, growth of farmed, wild and F 1 hybrid salmon was studied at contrasting densities within a hatchery and semi-natural environment. Farmed salmon significantly outgrew hybrid and wild salmon in all treatments. Importantly, however, the reaction norms were similar across treatments for all groups. Thus, this study was unable to find evidence that the offspring of farmed salmon have adapted more readily to higher fish densities than wild salmon as a result of domestication. It is suggested that the substantially higher growth rate of farmed salmon observed in the hatchery compared with wild individuals may not solely be caused by differences in their ability to grow in high-density hatchery scenarios.

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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 ◽

...

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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Potential for domesticated–wild interbreeding to induce maladaptive phenology across multiple populations of wild Atlantic salmon (Salmo salar)

Canadian Journal of Fisheries and Aquatic Sciences ◽

10.1139/f10-094 ◽

2010 ◽

Vol 67 (11) ◽

pp. 1768-1775 ◽

Cited By ~ 23

Author(s):

Dylan J. Fraser ◽

Cóilín Minto ◽

Anna M. Calvert ◽

James D. Eddington ◽

Jeffrey A. Hutchings

Keyword(s):

Atlantic Salmon ◽

Salmo Salar ◽

Common Garden ◽

Developmental Rate ◽

Wild Populations ◽

Southern Limit ◽

Farmed Salmon ◽

Atlantic Salmon Salmo Salar ◽

In The Wild ◽

Developmental Rates

We report how aquaculture may negatively alter a critical phenological trait (developmental rate) linked to survival in wild fish populations. At the southern limit of the species range in eastern North America, the persistence of small Atlantic salmon ( Salmo salar ) populations may be constrained by interbreeding with farmed salmon that escape regularly from intensive aquaculture facilities. Using a common-garden experimental protocol implemented over an 8-year period, we show that embryos of farmed salmon and multigenerational farmed–wild hybrids (F1, F2, wild backcrosses) had slower developmental rates than those of two regional wild populations. In certain cases, our data suggest that hybrid developmental rates are sufficiently mismatched to prevailing environmental conditions that they would have reduced survival in the wild. This implies that repeated farmed–wild interbreeding could adversely affect wild populations. Our results therefore reaffirm previous recommendations that based on the precautionary principle, improved strategies are needed to prevent, or to substantially minimize, escapes of aquaculture fishes into wild environments.

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The metabolic cost of turning right side up in the Mediterranean spur-thighed tortoise (Testudo graeca)

Scientific Reports ◽

10.1038/s41598-021-04273-w ◽

2022 ◽

Vol 12 (1) ◽

Author(s):

Heather E. Ewart ◽

Peter G. Tickle ◽

William I. Sellers ◽

Markus Lambertz ◽

Dane A. Crossley ◽

...

Keyword(s):

Video Analysis ◽

Metabolic Cost ◽

Physiological Process ◽

Specific Power ◽

Inverted Position ◽

Testudo Graeca ◽

Fitness Traits ◽

Evolutionary Advantage ◽

Cost Of Locomotion ◽

In The Wild

AbstractArmoured, rigid bodied animals, such as Testudines, must self-right should they find themselves in an inverted position. The ability to self-right is an essential biomechanical and physiological process that influences survival and ultimately fitness. Traits that enhance righting ability may consequently offer an evolutionary advantage. However, the energetic requirements of self-righting are unknown. Using respirometry and kinematic video analysis, we examined the metabolic cost of self-righting in the terrestrial Mediterranean spur-thighed tortoise and compared this to the metabolic cost of locomotion at a moderate, easily sustainable speed. We found that self-righting is, relatively, metabolically expensive and costs around two times the mass-specific power required to walk. Rapid movements of the limbs and head facilitate successful righting however, combined with the constraints of breathing whilst upside down, contribute a significant metabolic cost. Consequently, in the wild, these animals should favour environments or behaviours where the risk of becoming inverted is reduced.

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A single nuclei transcriptomic analysis of the Atlantic salmon gill through smoltification and seawater transfer

10.1101/2020.09.03.281337 ◽

2020 ◽

Author(s):

Alexander C. West ◽

Yasutaka Mizoro ◽

Shona H. Wood ◽

Louise M. Ince ◽

Marianne Iversen ◽

...

Keyword(s):

Gene Expression ◽

Atlantic Salmon ◽

Direct Evidence ◽

Cell Types ◽

Prior Work ◽

In The Wild ◽

Induced Changes ◽

Freshwater Environments ◽

Transcriptomic Studies

AbstractAnadromous salmonids begin life adapted to the freshwater environments of their natal streams before a developmental transition, known as smoltification, transforms them into marine-adapted fish. In the wild, the extending photoperiods of spring stimulates smoltification, typified by radical reprogramming of the gill from an ion-absorbing organ to ion-excreting organ. Prior work has highlighted the role of specialized “mitochondrion-rich” cells in delivering this phenotype. However, transcriptomic studies identify thousands of smoltification-driven differentially regulated genes, indicating that smoltification causes a multifaceted, multicellular change; but direct evidence of this is lacking.Here, we use single-nuclei RNAseq to characterize the Atlantic salmon gill during smoltification and seawater transfer. We identify 20 distinct clusters of nuclei, including known, but also novel gill cell types. These data allow us to isolate cluster-specific, smoltification-induced changes in gene expression. We also show how cellular make-up of the gill changes through smoltification. As expected, we noted an increase in the proportion of seawater mitochondrion-rich cells, however, we also identify a reduction of several immune-related cells. Overall, our results provide unrivaled detail of the cellular complexity in the gill and suggest that smoltification triggers unexpected immune reprogramming directly preceding seawater entry.

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Long-term declines in body size and shifts in run timing of Atlantic salmon in Ireland

Journal of Fish Biology ◽

10.1111/j.0022-1112.2006.01017.x ◽

2006 ◽

Vol 68 (6) ◽

pp. 1713-1730 ◽

Cited By ~ 49

Author(s):

T. P. Quinn ◽

P. McGinnity ◽

T. F. Cross

Keyword(s):

Body Size ◽

Atlantic Salmon ◽

And Shifts ◽

Run Timing

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Maladaptation and phenotypic mismatch in hatchery-reared Atlantic salmon Salmo salar released in the wild

Journal of Fish Biology ◽

10.1111/jfb.12543 ◽

2014 ◽

Vol 85 (6) ◽

pp. 1927-1945 ◽

Cited By ~ 19

Author(s):

R. Stringwell ◽

A. Lock ◽

C. J. Stutchbury ◽

E. Baggett ◽

J. Taylor ◽

...

Keyword(s):

Atlantic Salmon ◽

Salmo Salar ◽

Atlantic Salmon Salmo Salar ◽

In The Wild

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Adaptive divergence in shell morphology in an ongoing gastropod radiation from Lake Malawi

BMC Evolutionary Biology ◽

10.1186/s12862-019-1570-5 ◽

2020 ◽

Vol 20 (1) ◽

Cited By ~ 1

Author(s):

Bert Van Bocxlaer ◽

Claudia M. Ortiz-Sepulveda ◽

Pieter R. Gurdebeke ◽

Xavier Vekemans

Keyword(s):

Common Garden ◽

Shell Morphology ◽

Model Systems ◽

Shell Shape ◽

Adaptive Divergence ◽

Nominal Species ◽

Shape Variation ◽

In The Wild ◽

Evolutionary Radiations ◽

Contrasting Habitats

Abstract Background Ecological speciation is a prominent mechanism of diversification but in many evolutionary radiations, particularly in invertebrates, it remains unclear whether supposedly critical ecological traits drove or facilitated diversification. As a result, we lack accurate knowledge on the drivers of diversification for most evolutionary radiations along the tree of life. Freshwater mollusks present an enigmatic example: Putatively adaptive radiations are being described in various families, typically from long-lived lakes, whereas other taxa represent celebrated model systems in the study of ecophenotypic plasticity. Here we examine determinants of shell-shape variation in three nominal species of an ongoing ampullariid radiation in the Malawi Basin (Lanistes nyassanus, L. solidus and Lanistes sp. (ovum-like)) with a common garden experiment and semi-landmark morphometrics. Results We found significant differences in survival and fecundity among these species in contrasting habitats. Morphological differences observed in the wild persisted in our experiments for L. nyassanus versus L. solidus and L. sp. (ovum-like), but differences between L. solidus and L. sp. (ovum-like) disappeared and re-emerged in the F1 and F2 generations, respectively. These results indicate that plasticity occurred, but that it is not solely responsible for the observed differences. Our experiments provide the first unambiguous evidence for genetic divergence in shell morphology in an ongoing freshwater gastropod radiation in association with marked fitness differences among species under controlled habitat conditions. Conclusions Our results indicate that differences in shell morphology among Lanistes species occupying different habitats have an adaptive value. These results also facilitate an accurate reinterpretation of morphological variation in fossil Lanistes radiations, and thus macroevolutionary dynamics. Finally, our work testifies that the shells of freshwater gastropods may retain signatures of adaptation at low taxonomic levels, beyond representing an evolutionary novelty responsible for much of the diversity and disparity in mollusks altogether.

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Captive-bred Atlantic salmon released into the wild have fewer offspring than wild-bred fish and decrease population productivity

Proceedings of The Royal Society B Biological Sciences ◽

10.1098/rspb.2020.1671 ◽

2020 ◽

Vol 287 (1937) ◽

pp. 20201671

Author(s):

Ronan James O'Sullivan ◽

Tutku Aykanat ◽

Susan E. Johnston ◽

Ger Rogan ◽

Russell Poole ◽

...

Keyword(s):

Atlantic Salmon ◽

Natural Populations ◽

Mixed Population ◽

Lifetime Reproductive Success ◽

Wild Relative ◽

Offspring Survival ◽

Wild Populations ◽

Annual Productivity ◽

In The Wild ◽

Analyse Data

The release of captive-bred animals into the wild is commonly practised to restore or supplement wild populations but comes with a suite of ecological and genetic consequences. Vast numbers of hatchery-reared fish are released annually, ostensibly to restore/enhance wild populations or provide greater angling returns. While previous studies have shown that captive-bred fish perform poorly in the wild relative to wild-bred conspecifics, few have measured individual lifetime reproductive success (LRS) and how this affects population productivity. Here, we analyse data on Atlantic salmon from an intensely studied catchment into which varying numbers of captive-bred fish have escaped/been released and potentially bred over several decades. Using a molecular pedigree, we demonstrate that, on average, the LRS of captive-bred individuals was only 36% that of wild-bred individuals. A significant LRS difference remained after excluding individuals that left no surviving offspring, some of which might have simply failed to spawn, consistent with transgenerational effects on offspring survival. The annual productivity of the mixed population (wild-bred plus captive-bred) was lower in years where captive-bred fish comprised a greater fraction of potential spawners. These results bolster previous empirical and theoretical findings that intentional stocking, or non-intentional escapees, threaten, rather than enhance, recipient natural populations.

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Natural selection acts on Atlantic salmon major histocompatibility (MH) variability in the wild

Proceedings of The Royal Society B Biological Sciences ◽

10.1098/rspb.2006.0053 ◽

2007 ◽

Vol 274 (1611) ◽

pp. 861-869 ◽

Cited By ~ 34

Author(s):

Elvira de Eyto ◽

Philip McGinnity ◽

Sofia Consuegra ◽

Jamie Coughlan ◽

Jarle Tufto ◽

...

Keyword(s):

Natural Selection ◽

Atlantic Salmon ◽

Balancing Selection ◽

Natural Populations ◽

Class Ii ◽

Major Histocompatibility ◽

Genotype Frequencies ◽

Fitness Consequences ◽

In The Wild ◽

Class Ii Alpha

Pathogen-driven balancing selection is thought to maintain polymorphism in major histocompatibility (MH) genes. However, there have been few empirical demonstrations of selection acting on MH loci in natural populations. To determine whether natural selection on MH genes has fitness consequences for wild Atlantic salmon in natural conditions, we compared observed genotype frequencies of Atlantic salmon ( Salmo salar ) surviving in a river six months after their introduction as eggs with frequencies expected from parental crosses. We found significant differences between expected and observed genotype frequencies at the MH class II alpha locus, but not at a MH class I-linked microsatellite or at seven non-MH-linked microsatellite loci. We therefore conclude that selection at the MH class II alpha locus was a result of disease-mediated natural selection, rather than any demographic event. We also show that survival was associated with additive allelic effects at the MH class II alpha locus. Our results have implications for both the conservation of wild salmon stocks and the management of disease in hatchery fish. We conclude that natural or hatchery populations have the best chance of dealing with episodic and variable disease challenges if MH genetic variation is preserved both within and among populations.

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