The evolutionary ecology of reproductive timing and rapid senescence in pacific salmon

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The proposed research will focus primarily on the evolutionary ecology of reproductive scheduling in salmonid fishes. In most species of Pacific salmon, individuals achieve all their reproductive success in one short breeding season and die after a period of rapid physiological decline (senescence). Stored energy is used for migration and reproduction and must be carefully allocated between reproductive traits and body maintenance to ensure survival during the spawning season. Moreover, timing of migration, reproduction, and senescence are critically important to ensure that eggs get deposited, fertilized, and survive over the winter. This area of my research has three objectives: 1) determine whether variation in energy stores (fat, protein) and energy expenditure during spawning can explain variation in reproductive lifespan (i.e., the period between arrival at breeding sites and death), 2) determine how age-specific patterns of senescence evolve in response to anadromy and environmental mortality (predation risk and high stream temperatures), and 3) develop and test hypotheses for why some early-arriving females delay spawning after their arrival at breeding areas (i.e., pre-spawning waiting). The proposed research is important to evolutionary biologists, conservation biologists, the fishing industry, and the general public. It will contribute new information about how reproductive scheduling evolves by natural selection and will allow predictions to be made about the consequences of natural environmental or anthropogenic change. Such knowledge will inform fisheries and land-use management to ensure protection of phenotypic diversity.