Loren Rieseberg is a University Killam Professor at the University of British Columbia, Vancouver. Professor Rieseberg was born and raised in western Canada, but moved to the USA for his graduate education, receiving a PhD in Botany from Washington State University in 1987. He worked in the USA until 2006, first at the Rancho Santa Ana Botanic Garden in Southern California (1987-1993) and then at Indiana University (1993-2006), before returning to Canada.
Rieseberg’s lab employs population genomic approaches and field and greenhouse experiments to study the origin and evolution of plant species, exploit the genetic diversity of wild extremophile species for crop improvement, and combat invasive weeds, focusing on members of the sunflower family.
Rieseberg is a Clarivate Analytics Highly Cited Researcher, and his work has been recognized by MacArthur and Guggenheim Fellowships and the Darwin-Wallace Medal in evolutionary biology. He is an elected member of the Royal Societies of London and Canada, the Norwegian Academy of Arts and Letters, and the U.S. National Academy of Sciences. He is Past-President of the American Genetics Association and the Botanical Society of America, and has served as Chief Editor of Molecular Ecology since 1999.
Recombination and Speciation in the Annual Sunflowers
In sexual species, recombination is considered to be the greatest impediment to speciation. The main problem with recombination is that although divergent selection favors the buildup of associations between alleles favored in local environments and those causing reproductive isolation, gene flow and recombination break the associations apart. However, examples of speciation in the face of gene flow began accumulating in the late 20th century, with accelerating evidence over the past two decades. How can this happen?
In my talk, I will attempt to answer this question, drawing on a series of investigations of wild sunflower species, ranging from genome-wide association studies of phenotypic variation to field-based analyses of reproductive barrier strength, to functional characterization of candidate genes underlying reproductive isolation. I will show that most of the traits and genes that contribute to local adaptation and reproduction isolation in wild sunflowers are associated with chromosomal inversions or other recombination suppressors, thereby resolving the antagonism between selection and recombination. This genetic architecture appears to be common in other organisms, and thus offers a general solution for how speciation can occur in the presence of gene flow.