Spatial and temporal variation in biodiversity: patterns, mechanisms and applications

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One of the oldest observations in ecology is that biodiversity (e.g., the number of different species) varies enormously from place to place.  Human activities very frequently affect diversity.  Consequently it would be very useful to identify the processes that control diversity, and to show how human activities influence these.          Many hypotheses have been proposed to explain patterns of diversity.  These include the possibility of historical legacies of evolution and dispersal, contemporary caps on diversity, and dynamic processes that increase or decrease diversity.  The purpose of this work is to derive testable predictions from these hypotheses, to test the hypotheses, and to develop improved models that predict the variation of diversity through space and through time, as functions of observable habitat characteristics.  We do this at scales ranging from the entire globe to regions such as southern Ontario.          We will also address applied questions such as: can species decline be predicted?  Can we determine what factors are related to successful recovery of endangered species protected under the Species at Risk Act?        The approach I adopt is macroecological: that is, searching for patterns in large data sets that cover many different areas and many groups of species.  In studies at the global scale, experimental approach is rarely practical.  However, hypotheses about global phenomena often predict patterns that should be observed in nature, as well as how systems should respond to natural perturbations such as climate change.  I use these predicted broad-scale patterns to test global hypotheses.        The main impact of the proposed work is to resolve a very long-standing fundamental problem in our understanding of natural ecosystems: why are there more species in some places than others?  However, this work has applied impacts as well.  If we can identify the factors that control biodiversity, then we can assess how human activities affect those factors, and thus biodiversity.  Ultimately, the goal of my work is to be able to predict how human activities will affect the distribution of diversity on Earth.