Abstract:Oncorhynchus mykiss form partially migratory populations with anadromous fish that undergo marine migrations and residents that complete their life cycle in fresh water. Many populations' anadromous components are threatened or endangered, prompting interest in understanding ecological and evolutionary processes underlying anadromy and residency. In this paper, we synthesize information to better understand genetic and environmental influences on O. mykiss life histories, identify critical knowledge gaps, and suggest next steps. Anadromy and residency appear to reflect interactions among genetics, individual condition, and environmental influences. First, an increasing body of literature suggests that anadromous and resident individuals differ in the expression of genes related to growth, smoltification, and metabolism. Second, the literature supports the conditional strategy theory, where individuals adopt a life history pattern based on their conditional status relative to genetic thresholds along with ultimate effects of size and age at maturation and iteroparity. However, except for a generally positive association between residency and high lipid content plus a large attainable size in fresh water, the effects of body size and growth are inconsistent. Thus, individuals can exhibit plasticity in variable environments. Finally, patterns in anadromy and residency among and within populations suggested a wide range of possible environmental influences at different life stages, from freshwater temperature to marine survival. Although we document a number of interesting correlations, direct tests of mechanisms are scarce and little data exist on the extent of residency and anadromy. Consequently, we identified as many data gaps as conclusions, leaving ample room for future research.Résumé : Les truites arc-en-ciel (Oncorhynchus mykiss) forment des populations partiellement migratrices incluant des individus anadromes qui effectuent des migrations marines et des individus résidents dont le cycle biologique se déroule entièrement en eau douce. Les éléments anadromes de nombreuses populations sont menacés ou en voie de disparition, ce qui suscite un intérêt envers la compréhension des processus écologiques et évolutionnaires qui sous-tendent l'anadromie et la résidence. Nous présentons une synthèse de l'information disponible dans le but de mieux comprendre les influences génétiques et environnementales sur les cycles biologiques d'O. mykiss, de cerner les lacunes critiques en matière de connaissances et de proposer des avenues de recherche future. L'anadromie et la résidence semblent témoigner d'interactions entre la génétique, l'état des individus et des influences environnementales. D'abord, de plus en plus d'études donnent à penser que les individus anadromes et résidents diffèrent sur le plan de l'expression des gènes associés à la croissance, à la smoltification et au métabolisme. Deuxièmement, la documentation appuie la théorie de la stratégie conditionnelle selon laquelle les individus adoptent un m...
Background Patient or person centred care is widely accepted as the philosophy and practice that underpins quality care. An examination of the Australian National Chronic Disease Strategy and literature in the field highlights assumptions about the self-manager as patient and a focus on clinical settings.
Alternative male phenotypes in salmonine fishes arise from individuals that mature as larger and older anadromous marine-migrants or as smaller and younger freshwater residents. To better understand the processes influencing the expression of these phenotypes we examined the influences of growth in length (fork length) and whole body lipid content in rainbow trout (Oncorhynchus mykiss). Fish were sampled from the John Day River basin in northeast Oregon where both anadromous ("steelhead") and freshwater resident rainbow trout coexist. Larger males with higher lipid levels had a greater probability of maturing as a resident at age-1+. Among males, 38% were maturing overall, and the odds ratios of the logistic model indicated that the probability of a male maturing early as a resident at age-1+ increased 49% (95% confidence interval (CI)=23-81%) for every 5 mm increase in length and 33% (95% CI=10-61%) for every 0.5% increase in whole body lipid content. There was an inverse association between individual condition and water temperature as growth was greater in warmer streams while whole body lipid content was higher in cooler streams. Our results support predictions from life history theory and further suggest that relationships between individual condition, maturation, and environmental variables (e.g., water temperature) are shaped by complex developmental and evolutionary influences.
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