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The consumption of invasive, high-thiaminase prey fishes can cause thiamine deficiency, which has been hypothesized to be a major barrier for lake trout (Salvelinus namaycush (Walbaum in Artedi, 1792)) restoration in the Great Lakes. In fishes, an understudied aspect of thiamine deficiency is its effect on cardiac function, despite evidence of this effect in mammals. Here, parr of two strains of lake trout (Seneca and Slate) were raised on either a control or high-thiaminase diet for nine months. We then measured cardiac function and morphology, particularly as it relates to the ability of the heart to meet oxygen demands at warmer water temperatures. The thiaminase diet was associated with significant heart enlargement and reduced cardiac performance at high temperatures. These effects were observed in both strains but were more pronounced in Slate strain fish. Our data suggest that dietary thiaminase impairs cardiac function in fishes and that these impairments may become increasingly important as water temperatures increase through climate change. Key words: thiaminase, invasive species, thermal performance, cardiac function, lake trout, Salvelinus namaycush, Introduction In recent years, thiamine (vitamin B1) deficiency has increasingly been reported in wild animal populations around the world (Balk et al. 2016). Thiamine deficiency is taxonomically widespread, with populations [...]

The pace of life hypothesis (POLS) predicts that personality traits, like activity and boldness, are positively correlated with growth and metabolism. Here, we assess whether personality could predict body mass, metabolic rate, and performance under stress for hatchery-raised Atlantic salmon (Salmo salar) 15 months post fertilization. Personality was evaluated for individual fish using a series of repeated trials alongside two stressful events (PIT tagging, simulated transport), to determine performance under stress. Standard metabolic rate (SMR) was then assessed via intermittent flow respirometry, and the relationships between personality, body mass, performance, and SMR were evaluated. Fish displayed repeatable behaviours, but not in accordance with POLS hypothesis. Smaller fish were more active and responsive to stimuli, while personality was not associated with SMR. Although smaller fish and fish with higher SMR both performed better under stress, body mass was unrelated to SMR. We discuss the utility of supporting the occurrence of a wider range of growth rates and body sizes in hatchery environments, as a means of promoting greater stress tolerance as well as faster growth. Key words: hatchery-raised, pace of life, personality, Salmo salar, SMR, performance under stress L'hypothese du rythme de vie predit que des traits de personnalite, comme l'activite et la hardiesse, sont positivement correles a la croissance et au metabolisme. Nous tentons de determiner si la personnalite peut permettre de predire la masse du corps, le metabolisme et la performance en situation de stress pour des saumons atlantiques (Salmo salar) eleves en ecloseries a 15 mois post-fecondation. La personnalite individuelle est evaluee en utilisant une serie d'essais repetes jumeles a deux evenements stressants (pose d'une etiquette PIT, transport simule) afin de determiner la performance en situation de stress. Le taux metabolique standard (TMS) est ensuite evalue par respirometrie par debit intermittent, et les relations entre la personnalite, la masse corporelle, la performance et le TMS sont evaluees. Les poissons presentent des comportements pouvant etre reproduits, mais pas de maniere conforme a l'hypothese du rythme de vie. Les poissons plus petits sont plus actifs et reagissent plus aux stimuli, alors que la personnalite n'est pas associee au TMS. Si les poissons plus petits et les poissons au TMS plus eleve performent mieux en situation de stress, la masse corporelle n'est pas reliee au TMS. Nous abordons l'utilite de soutenir la presence d'une plus grande fourchette de taux de croissance et de tailles du corps dans les ecloseries comme approche pour favoriser une meilleure tolerance au stress ainsi qu'une croissance plus rapide. [Traduit par la Redaction] Mots-cles : eleve en ecloserie, rythme de vie, personnalite, Salmo salar, TMS, performance en situation de stress, Introduction The study of life history emerged from observations regarding age-specific patterns of survival and reproduction that exhibit a distribution of 'fast' and 'slow' traits when plotted along a single [...]

Exotic prey fishes that have high thiaminase levels are associated with a thiamine deficiency and reduced fitness in many salmonids. If sensitivity to low thiamine availability differs among the three Atlantic salmon (Salmo salar) populations targeted for reintroduction into Lake Ontario, this could substantially influence their performance. We quantified the effects of a low-thiamine diet and a control diet on tissue thiamine concentrations, survival, growth rate, and reproductive traits (sperm and egg quality) in Atlantic salmon from the three candidate source populations. Fish that consumed the low-thiamine diet had comparable growth rates but lower survival and lower muscle thiamine concentrations (26 nmol * [g.sup.-1]) than control fish (34 nmol * [g.sup.-1]). Sperm count, velocity, motility, and longevity did not differ based on diet. Embryo survival was lower for females fed the low-thiamine diet, and the low-thiamine diet was associated with significantly lower egg thiamine concentrations (11 versus 17 nmol * [g.sup.-1]). The effects of the low-thiamine diet did not differ among the tested populations, which suggests that source population selection is unlikely to fully overcome this potential challenge for re-establishing wild populations. Des poissons proies exotiques qui presentent de fortes concentrations de thiaminase sont associes a une deficience en thiamine et une reduction de l'aptitude chez de nombreux salmonides. Si la sensibilite a une faible disponibilite de thiamine varie entre les trois populations de saumons atlantiques (Salmo salar) ciblees pour des efforts de reintroduction dans le lac Ontario, cela pourrait avoir une incidence significative sur leur performance. Nous avons quantifie les effets d'un regime alimentaire faible en thiamine et d'un regime alimentaire temoin sur les concentrations de thiamine dans les tissus, la survie, le taux de croissance et des caracteres associes a la reproduction (qualite du sperme et des reufs) chez des saumons atlantiques des trois populations sources candidates. Les poissons au regime alimentaire faible en thiamine presentaient des taux de croissance semblables, mais des taux de survie et des concentrations de thiamine dans les muscles (26 nmol * [g.sup.-1]) plus faibles que les poissons temoins (34 nmol * [g.sup.-1]). Le nombre, la vitesse, la motilite et la longevite des spermatozoides ne variaient pas en fonction de l'alimentation. La survie des embryons etait plus faible pour les femelles au regime alimentaire faible en thiamine, et ce dernier etait associe a des concentrations de thiamine dans les reufs significativement plus faibles (11 contre 17 nmol * [g.sup.-1]). Les effets du regime alimentaire faible en thiamine ne variaient pas entre les populations etudiees, ce qui porte a croire qu'il est peu probable que le choix des populations soit suffisant pour surmonter completement cette difficulte potentielle du retablissement de populations sauvages. [Traduit par la Redaction], Introduction Atlantic salmon (Salmo salar) were once abundant in Lake Ontario, but were extirpated by 1898 due to habitat degradation and over-exploitation (Crawford 2001). The current efforts to reintroduce Atlantic [...]

Although studies addressing natural selection have primarily focused on additive genetic effects because of their direct relationship with responses to selection, nonadditive genetic and maternal effects can also significantly influence phenotypes. We partitioned the phenotypic variance of survival and fitness-related traits in juvenile Atlantic salmon (Salmo salar) from three allopatric populations (LaHave, Sebago, and Saint-Jean) into additive genetic, nonadditive genetic, and maternal environmental effects using a full-factorial breeding design. We also modelled the potential increase in offspring performance if nonrandom mating (e.g., mate choice) is considered instead of random mating. The three populations exhibited significant differences in trait values as well as the genetic architecture of the traits. Nevertheless, nonadditive genetic and maternal environmental effects tended to be larger than the additive genetic effects. There was also a shift from maternal environmental to genetic effects during development in two of the populations. That is, maternal environmental effects were larger at early (egg and alevin) life stages, whereas nonadditive effects were larger at the later (fry) life stage. The amount of additive genetic effects was small, suggesting the traits will respond slowly to selection. We discuss how different maternal environmental effects across years may influence the genetic architecture of offspring traits. Si les etudes sur la selection naturelle se sont principalement interessees aux effets genetiques additifs en raison de leur lien direct avec les reactions a la selection, les effets genetiques non additifs et les effets maternels peuvent egalement exercer une influence significative sur les phenotypes. Nous avons subdivise la variance phenotypique de caracteres associes a la survie et a l'aptitude chez des saumons atlantiques (Salmo salar) juveniles de trois populations allopatriques (LaHave, Sebago et Saint-Jean) en des effets genetiques additifs, genetiques non additifs et relies a l'environnement maternel, en utilisant un plan factoriel complet de l'accouplement. Nous avons egalement modelise l'augmentation potentielle de la performance de la progeniture pour un scenario d'accouplement non aleatoire (p. ex. choix du partenaire) plutot que d'accouplement aleatoire. Les trois populations presentaient des differences significatives en ce qui concerne la valeur et l'architecture genetique des caracteres. Cela dit, les effets genetiques non additifs et les effets de l'environnement maternel avaient tendance a etre plus grands que les effets genetiques additifs. En outre, dans deux des populations, les effets initiaux de l'environnement maternel cedaient le pas a des effets genetiques au cours du developpement. Autrement dit, les effets de l'environnement maternel etaient plus forts aux premieres etapes du cycle de vie (reufs et alevins vesicules), alors que les effets non additifs etaient plus importants a l'etape plus tardive (fretin). La quantite des effets genetiques additifs etait faible, donnant a penser que les caracteres reagissent lentement a la selection. Nous discutons de l'influence possible de differents effets de l'environnement maternel sur l'architecture genetique des caracteres de la progeniture. [Traduit par la Redaction], Introduction Quantitative genetic studies addressing responses to selection have primarily focused on additive genetic effects (Falconer and Mackay 1996). By contrast, the importance of nonadditive genetic effects on phenotypic variation [...]

Reproductive efforts are energetically costly and often result in significant trade-offs with other metabolic processes. In many animals, androgens influence how this energy is allocated during the breeding period. In this study, androgen levels of parental bluegill sunfish (Lepomis macrochirus Rafinesque, 1819) were manipulated by implanting males with either 11ketotestosterone (11-KT) or flutamide (an androgen receptor antagonist) shortly after spawning. Parental behaviours were assessed for 3 days after implantation. Differential brain gene expression between the two groups was examined using a 44 000 microarray gene chip. We found that 11-KT-implanted males exhibited lower levels of expression of genes related to immune function compared with flutamide-implanted males, suggesting that high androgen levels negatively affect the male immune system. These data thus indicate that a significant trade-off may exist between maintaining high levels of androgens and decreased immune function in parental male bluegill. Key words: immune function, androgens, parental care, gene expression, bluegill sunfish, Lepomis macrochirus. Les efforts de reproduction sont couteux sur le plan energetique et se traduisent souvent par d'importants compromis en ce qui concerne d'autres processus metaboliques. Chez de nombreux animaux, les androgenes influencent l'affectation de cette energie durant la saison de reproduction. Dans cette etude, les teneurs d'androgenes de crapets arlequins (Lepomis macrochirus Rafinesque, 1819) parentaux ont ete manipulees en implantant dans des males soit de la 11-cetotestosterone (11-KT) ou de la flutamide (un antagoniste des recepteurs d'androgenes) peu apres le frai. Les comportements parentaux ont ete evalues pendant 3 jours apres l'implantation. Les differences d'expression des genes du cerveau entre les deux groupes ont ete examinees a l'aide d'une puce a genes 44 000. Nous avons constate que les males dans lesquels avait ete implantee de la 11-KT presentaient des niveaux plus faibles d'expression de genes associes a la fonction immunitaire que les males ayant fait l'objet d'une implantation de flutamide, ce qui donne a penser que de fortes teneurs d'androgenes ont un effet negatif sur le systeme immunitaire des males. Ces donnees indiquent donc qu'il pourrait y avoir un important compromis entre le maintien de fortes teneurs d'androgenes et la reduction de la fonction immunitaire chez les crapets arlequins males parentaux. [Traduit par la Redaction] Mots-cles: fonction immunitaire, androgenes, soins parentaux, expression genique, crapet arlequin, Lepomis macrochirus., Introduction Reproduction is one of the most important times in the life of an individual because reproductive success is a main component of fitness. Reproduction is energetically costly, which leads [...]

Prolactin and 11‐ketotestosterone (11‐KT) are important reproductive hormones in fishes, which may also influence immunocompetence. The immunocompetence handicap hypothesis states that higher androgen concentrations that support secondary sex traits are traded off against a decrease in immune system function. To test the relationships between these hormones and immunocompetence, we experimentally manipulated 11‐ketotestosterone and prolactin in the freshwater fish, bluegill (Lepomis macrochirus) during parental care using implants that contained either 11‐KT, prolactin, or an inert control. We vaccinated individuals to stimulate the acquired immune response, then measured immunocompetence as the number of granulocytes, lymphocytes and monocytes, and the expression of interleukin 8 in each sample. We did not observe any significant differences in the immune measures among the hormone treatments. Our results indicate that in bluegill, there is no trade‐off between androgens or prolactin and immunocompetence. Research Highlights: Prolactin or androgen (11‐KT) treatment did not affect immune responses in bluegill sunfish.We find no support the immunocompetence handicap hypothesis in fish.Increased 11‐KT affected behavior, but not the immune response to a vaccine. [ABSTRACT FROM AUTHOR]

Sexual selection is recognized as an important evolutionary force in salmon. However, relatively little is known about variation in sexual selection pressures across salmon populations or the potential role of natural selection as a driver of adaptive mating patterns. Here, we examine mating behaviour and correlates of reproductive success in Chinook salmon (Oncorhynchus tshawytscha) from the Quinsam and Little Qualicum rivers in British Columbia, Canada--two populations for which we have previously found evidence of natural selection operating on major histocompatibility complex (MHC) genes. In both populations, males courted females and exhibited dominance behaviour towards other males, and the frequency of each behaviour was positively associated with reproductive success. Males were more aggressive towards females with whom they would produce offspring of low or high MHC class II diversity, and the offspring of males from the Quinsam River exhibited higher diversity at the MHC class I than expected. We discuss our results in relation to local natural selection pressures on the MHC and the potential for MHC-dependent mate choice. La selection sexuelle est reconnue comme etant un important moteur devolution chez le saumon. On en sait cependant assez peu sur la variation des pressions de selection sexuelle d'une population de saumons a l'autre ou sur le role eventuel de la selection naturelle comme determinant des modes d'accouplement adaptatifs. Nous examinons le comportement d'accouplement et les correlats du succes de reproduction chez le saumon quinnat (Oncorhynchus tshawytscha) des rivieres Quinsam et Little Qualicum, en Colombie-Britannique (Canada), deux populations pour lesquelles nous avons deja demontre la presence d'une selection naturelle s'operant sur des genes du complexe majeur d'histocompatibilite (MHC). Dans les deux populations, les males courtisent les femelles et presentent un comportement de dominance envers les autres males, et la frequence de ces comportements est positivement associee au succes de reproduction. Les males sont plus agressifs envers les femelles avec lesquelles ils vont produire une descendance de diversite faible ou forte au niveau de la classe II du MHC et la descendance des males de la riviere Quinsam presente une plus grande diversite que prevu au niveau de la classe I du MHC. Nous discutons de nos resultats en ce qui concerne les pressions de selection naturelle locales sur le MHC et la possibilite d'une selection de partenaire dependant du MHC. [Traduit par la Redaction], Introduction In salmonid fishes, sexual selection has led to much of the diversity we see in mating behaviour and secondary sexual characteristics (de Gaudemar 1998). Salmonids have also evolved in [...]