The geographic, genetic, and ecological factors driving the evolution of species found in sympatry have been of longstanding interest to evolutionary biologists. In addition, understanding how these factors generate and sustain biodiversity is increasingly important for the design of effective conservation programmes. Comparative analysis of contact zones between pairs of species can provide insights into the relative roles of factors driving speciation.
I review our recent research on contact zones in three such pairs, Dolly Varden and bull trout (Salvelinus malma and S. confluentus), Dolly Varden and Arctic char (S. alpinus) and lake-stream pairs of threespine sticklebacks (Gasterosteus aculeatus). Using a mixture of bio/phylogeographic, population genetic, and ecological approaches, our work on these systems suggests that a diversity of geographic and ecological processes, working across diverse time scales, operate and maintain genetic distinction despite some gene flow between species. Comparative study of contact zones in char and sticklebacks illustrate the importance of understanding both the historical and contemporary factors that bring populations into contact and that influence their potential interactions post-contact. Further, even within the same general geographic arena, a diversity of spatial and temporal processes appear to operate to promote the origin and persistence of biodiversity at different evolutionary scales – from well diverged taxa to nascent species.
E.B. Taylor
Department of Zoology and Biodiversity Research Centre,
University of British Columbia, Vancouver, Canada