Grant: Discovery Grants Program - Individual

The evolution of high latitude species is linked to both historical and contemporary environmental changes. One way to understand the historical processes influencing the species? distribution is through the use of molecular markers. These markers retain information on historical events in addition to contemporary processes. Northern North America contains several areas of secondary contact between populations from different Pleistocene refugia that were isolated for thousands of years. My current research program uses a comparative approach to investigate population genetic structure. By understanding how past climate changes and landscape features have shaped contemporary populations, we can better understand their population dynamics, and metapopulation functioning and perhaps predict how they will respond to future climate change. In addition, we can gain further insights into ecological diversification by focusing on closely related sympatric species. My long term goals focus on the role of landscape features and historical range shifts on population level processes and patterns of population connectivity. My research has revealed contrasting genetic patterns in some co-distributed species with similar life history patterns and habitat requirements. Some of the patterns correspond to known physical barriers, but others do not and warrant further study to determine the barriers to dispersal. The patterns of postglacial colonization for my study species are now better understood as a direct result of my research. The short term goals of my research program are to study: 1) micro- and macro-geographic population structure in species with mixed migration strategies, and 2) intra- and inter-specific contact zones to examine microgeographic landscape genetics. The combination of short term projects also allows us to study the speciation process. For example, what is the influence of migratory behaviour on intraspecific gene flow or more specifically do resident populations have higher levels of population structure than migratory populations of the same species? In the last few years, major advances in genetic analyses have occurred allowing researchers to answer questions that were not possible even a decade ago. GIS technologies and Bayesian analyses now allow me to create historical range maps for individual species using paleoclimate data and compare these to our genetic data. Combining the newer and more powerful analyses with traditional markers and a larger number of species will allow us to better understand evolutionary processes. Using genetic tools, I will determine if geographic variation is the result of restricted gene flow or other ecological factors. By employing a combination of mitochondrial (mtDNA) and nuclear (microsatellite and single nucleotide polymorphisms (SNPs)) loci, I will be able to obtain a more complete and accurate picture of rangewide gene flow and fine scale population genetic structure. By examining fine scale differences in western North America species, such as purple finch, and adding data on species with mixed migration strategies, we will gain a better understanding of how gene flow is occurring as a result of behavioural and ecological differences. Furthermore by comparing data from different classes of highly variable markers and the different species occupying similar geographic areas, we can assess whether or not there is a common genetic signature on the patterns of variation and population structure.