Diversification, adaptation and speciation in a temperate frog

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Despite over a half-century of incredible advances in our understanding of speciation mechanisms, there remain outstanding issues. In particular we lack comprehensive information on the geography and temporal sequence for the evolution of barriers to mating between evolutionary lineages [the hallmarks of speciation] across the entire range of single species. How has range fragmentation, precipitated by glaciations, ultimately impacted the evolution of reproductive isolating barriers? Does selection against hybridization after contact of long sundered lineages enhance differences in mating preferences, a process called reinforcement? Can differences in the mating system, particular breeding phenology (sequence of breeding activities), arise at fine scales under divergent ecological selection and restricted dispersal scenarios? We address these questions using genetic and experiment studies of a small North American frog, the spring peeper. For our first project, we identified major secondary contact zones between different pairs of lineages throughout the species' range, and will test for (1) key differences in the mate recognition system between lineages, (2) the genetic basis for male call and female preference differences for them, (3) evidence for genetic incompatibilities in hybrids, and (4) evidence for secondary reinforcement. Our second project will examine the ecological mechanisms that may cause such divergence. Specifically within an environmentally heterogeneous 2500 sq. km. area in Eastern Ontario, we will test whether selection pressures in habitats differing in vegetation structure and microclimate can produce significant differences in (1) spring emergence and calling times of males, and (2) the acoustic properties of male advertisement calls. Combined insights from these projects will advance our knowledge of the interplay among, geographical isolation, contact zone dynamics, and ecological selection in speciation. Together our results speak to how climate change has and can in the future alter evolutionary trajectories. The research provides exceptional training in evolutionary ecology for a minimum of 44 students.