The nature of genetic diversity, population size and adaptation: applications to conservation biology

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Human impacts on the environment have reduced the number of individuals within many wild species to very low levels. This is a concern to conservation biologists because species with small numbers may have an increased chance of going extinct. For example, small populations often exhibit low levels of genetic diversity, which is thought to reduce the likelihood that at least some individuals in such populations will survive and reproduce if the environment changes, what scientists refer to as reduced adaptability. Is there much evidence in nature of reduced adaptability in small populations? To date, it turns out that this has not been sufficiently studied to generalize, but it is important for society to know because it influences how we approach several conservation efforts to protect the environment and different species in the face of further human development. My proposed research program will examine relationships between population size, genetic diversity and adaptability in a salmonid fish species (brook charr) that is important to many commercial, recreational and aboriginal subsistence fisheries. Specifically, across multiple watersheds, I will determine whether small populations of brook charr do in fact exhibit reduced genetic diversity and adaptability relative to large populations. Field and laboratory studies will be carried out to understand (i) what environmental factors influence adaptability in natural populations of varying size, and (ii) how well small populations respond to environmental changes relative to large populations under conditions that will likely arise with future climate warming. For management agencies of several socio-economically important fish species across Canada, and for the international conservation community, my research will contribute significant new knowledge towards addressing several key environmental issues: (i) how large nature reserves should be to maintain viable populations of different species; (ii) whether small, isolated populations should receive a high priority for conservation; and (iii) how specific populations might respond to future environmental change (e.g. climate warming).