Quantitative genetic variation and genotype by environment interaction of embryo development rate in pink salmon (Oncorhynchus gorbuscha)

Abstract

Quantitative genetic variation of development rate was evident among 20 half-sib and 40 full-sib families within each of two seasonally separate components of a population of pink salmon (Oncorhynchus gorbuscha) (H o : no sire effect on temperature units at hatch, P < 0.02). Differences between averages of families spawned 3 weeks apart may have had genetic or environmental sources (e.g., in constant 8°C, early embryos hatched at 606 temperature units, and late embryos, at 625). Statistical interactions between paternal effects and environment (embryos were cultured in four temperature regimes, two simulated natural regimes and two constant temperatures; H o : no sire by regime interaction effect on temperature units at hatch, P < 0.09) were weak evidence that genotype by environment interactions contributed to variation. Paternal effects in analysis of variance (evidence of additive genetic variation) were detected only at later stages. Evidences of genetic variation and of interactions between genotypes and environments are pertinent to resource conservation because they suggest that harvest management or hatchery practice have the potential to reduce genetic variation in salmon populations.Résumé : Une variation génétique quantitative du taux de développement était apparente chez 20 familles de demifrères et 40 familles de plein-frères au sein de deux composantes saisonnières distinctes d'une population de saumon rose, Oncorhynchus gorbuscha. (H o : aucun effet du père sur le nombre d'unités de température au moment de l'éclosion, P < 0,02). Les écarts notés entre les moyennes des familles dont la fécondation présentait trois semaines d'intervalle peuvent s'expliquer par des facteurs génétiques ou environnementaux (p. ex. : à une température constante de 8°C l'éclosion des embryons se produisait à 606 unités de température pour les plus hâtifs et à 625 pour les plus tardifs). Les interactions statistiques entre les effets paternels et l'environnement (embryons élevés sous quatre régimes de température, deux régimes naturels simulés et deux à température constante; H o : aucune interaction père-régime sur les unités de température à l'éclosion, P < 0,09) constituaient un indice faible du faible apport à la variation des effets de l'environnement sur le génotype. Une analyse de variance des effets paternels (évidence d'une variation génétique additive) n'a permis de mettre ces derniers en évidence qu'aux stades ultérieurs. L'existence de signes de variation génétique et d'interactions entre les génotypes et les environnements s'avère pertinente pour la conservation des ressources car elle indique que la gestion de la récolte ou les pratiques des piscicultures pourraient influer sur la variation génétique des populations de saumon.[Traduit par la Rédaction]

Genetic change for earlier migration timing in a pink salmon population

“…Adaptations-by-time [55] for different thermal regimes and biotic interactions are well documented for this population, and there is evidence that early-migrating adult fish are adapted to warmer conditions at multiple life stages and life-history events (e.g. juvenile developmental rates and migration timing, and adult migration timing, lifespan and breeding date) [37,41,56,57]. These patterns of local adaptation result in a strong temporal structuring of the population [37].…”

The Transcriptional Landscape of Cross-Specific Hybrids and Its Possible Link With Growth in Brook Charr (Salvelinus fontinalis Mitchill)

“…Thus, gene dominance from the biggest parental population may explain the performance of these hybrids. At early life stages, the maternal genome may influence size through gene products contained in the egg (Hebert et al 1998;Nakajima and Taniguchi 2002). Indeed, previous studies on the L population have revealed that maternal effects are acting until yolk sac resorption and are correlated with the size of the mother (Perry et al 2005).…”

Quantitative Trait Loci × Maternal Cytoplasmic Environment Interaction for Development Rate in Oncorhynchus mykiss

“…Salmonid fishes suffer severe mortality when they emerge from the gravel nests in which they are fertilized (Elliot 1989). Emergence timing is also influenced by spawning date in salmonids, but embryonic 1 development rate, thought to be adapted to local thermal environments (Tallman 1986;Beacham 1988;Hebert et al 1998), also has significant effects on emergence size and timing. Fish that hatch earlier have a size advantage over fish that hatch later (Mason and Chapman 1965), but timing of emergence must be carefully balanced with conditions for food availability (Sundstrom et al 2004(Sundstrom et al , 2005.…”

“…Considerable additive genetic variance for development rate has been revealed through quantitative genetic studies (Smoker 1986;Beacham 1988;Hebert et al 1998), and heritability has been reported as high as 0.23 in steelhead trout, O. mykiss (McIntyre and Blanc 1972). Many studies have shown that variation in development rate and survival prior to hatch is also significantly influenced by maternal effects (McIntyre and Blanc 1972;Blanc and Poisson 1983;Smoker 1986;Brown et al 2006).…”