Advances in population and landscape genetics now allow us to answer previously intractable ecological questions.
Landscape genetics is a relatively new area of emphasis in the Biogeography Lab. The lab is interested in questions related to ecological biogeography that can be addressed using advances in genetics and genomics techniques. We are particularly interested in answering questions within a landscape genetics framework that are linked to climate change and that build on our lab’s expertise in landscape ecology and vegetation response to climate change. We have a long history of investigating processes of range expansion of species through the study of ecotones and are placing an emphasis on using genetics to investigate how ecotones may shift during changing climates. We are interested in questions about plant dispersal at short and long time scales and how this can be incorporated better into simulation and statistical models. Two specific projects are described below.
Dispersal at treeline
As future climates are expected to change much more rapidly than in the past, it is important to understand the migration potential of species to predict what future ecosystems may look like. The extent to which seedling establishment at treeline is occurring as a function of local seed production is unknown. Our lab is addressing these questions by quantifying long distance dispersal using landscape genetics techniques. A genetic analysis, using both established microsatellite markers and next generation sequencing, is investigating local and regional genetic variability in mountain hemlock (Tsuga mertensiana) treelines on the Kenai Peninsula, Alaska. Population genetic structure is being analyzed using probabilistic assignment methods, and dispersal distance is being quantified at a local site through parentage analysis. This research will allow us to have a better understanding of treeline migration potential and will provide a mechanism for parameterizing fat-tailed dispersal kernels, which can be used in dynamic vegetation models.
Coastal Douglas fir populationsArguably climate change and landscape fragmentation are two of the biggest ecological challenges of our generation. The ability of plant populations to respond rapidly to changing landscapes will depend on the complex interactions between landform, climate and biota. Landscape genetics is a framework that integrates the spatial and temporal components of geography and landscape ecology with the theoretical and evolutionary approaches of molecular ecology and population genetics. This approach allows us to assess how matrix quality, landscape configuration and composition influence genetic variation. Our lab is currently addressing how landscape heterogeneity has influenced dispersal and gene flow in Coastal Douglas-Fir (Pseudotsuga menziesii). In brief, we have found little isolation by distance in Douglas-Fir populations and that geographically close sub-populations show a greater degree of genetic differentiation than more distant sub-populations suggesting isolation by resistance or isolation by adaptation. Future research will focus on developing resistance models that will more accurately identify which landscape features or climate variables specifically contribute to this genetic divergence. We will better understand how this commercially and economically important tree species will respond to changing landscapes.