作者: Morgan H. Bond , Jessica A. Miller , Thomas P. Quinn
DOI: 10.1890/14-1551.1
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摘要: Across animal taxa, migration allows individuals to exploit habitats and resources that predictably vary seasonally in suitability. Theory predicts the "decision" migrate or not is shaped by relative fitness costs benefits of exhibiting a given life history. Adoption migratory strategy widely thought reflect dichotomous outcome; are either resident migratory, continue exhibit this history until death. In fishes, anadromy freshwater residency represents well-studied dichotomy. Resident may adopt later life, but known abandon pattern. Here, we investigated benefits, as measured body size, salmonid fish, Dolly Varden, Salvelinus malma, Alaska, reveal novel history: cessation older, larger individuals. Otolith microchemical analysis Varden showed while most fish migrated sea at least once their lives, lifelong exist streams with close proximity ocean. Moreover, probability seaward any year decreased annually after an individual's fourth year, no eighth oldest were captured 11th year. Migration conferred size advantage young marine foraging declined older which time increasingly "retired from anadromy." Additionally, measurement both natal otolith chemistry gonadosomatic index indicated continued contribution lifetime fitness, rather than senescence, retired We suggest reversion viable because opportunities subsidized predictable annual supply energy-rich eggs carcasses spawning Pacific salmon.