Evolutionary ecology and conservation biology of fishes

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My research focuses on the tremendous variability in reproductive strategies within and among natural populations. Such life-history variation is reflected by individual differences in fitness-related characters, such as age & size at maturity, number of eggs per female, and offspring size. To what extent is the source of this variability genetic, environmental, or some combination thereof? This is a fundamental question to evolutionary ecology and conservation biology. Firstly, the source of this variation determines whether life-history responses to environmental perturbations, such as habitat alteration and harvesting, will be rapid, slow, or indeed whether they will occur at all. Secondly, the nature of the life-history response can affect a population's ability to recover from collapse, persist through time, and sustain exploitation. Using several species of fish as study organisms, my general objectives are: 1) to determine how alternative reproductive tactics are maintained in variable environments; 2) to assess the adaptive significance of sex-biased dispersal and mobility; 3) to study factors that affect the ability of populations to recover following collapse to historically unprecedented levels of abundance; and 4) to evaluate the influence of fisheries-induced evolution on phenotypic plasticity. Specifically, my first study asks how different male reproductive tactics persist within populations of Atlantic salmon. The second, building upon a 20-year data set, seeks to understand why males disperse further, and have greater mobility, than females within a stream population of brook trout. The third study explores factors related to mating and reproduction that may hinder the recovery of marine fish, such as the Atlantic cod which has declined 99% off Newfoundland since 1992. Using zebrafish, the fourth project examines whether size-differential mortality can generate a selection response in life-history reaction norms over several generations, potentially leading to a reduced individual capacity to respond to environmental change. The significance of the proposed research to evolutionary ecology and conservation biology lies in its potential to predict life-history responses to short- and long-term environmental change.