Symposium II: Polyploidy, Heterosis, and Genomic Plasticity
S022: Genomic Footprints of Hybridization
Rieseberg, Loren Contact Presenter||Authors||Rieseberg, Loren (A) Barker, Mike (A) Dlugosch, Katrina (A) |
(A): Department of Botany, University of British Columbia|
The role of hybridization in evolution has been subject of intense discussion and speculation for more than a century. At one extreme, hybridization is considered to be a potent evolutionary force that contributes to adaptive evolution and speciation. In this view, the new gene combinations generated by hybridization promote the development and acquisition of novel adaptations. Others, in contrast, accord little evolutionary significance to hybridization, viewing it as a primarily local phenomenon with only transient effects. Unfortunately, definitive support for either viewpoint is lacking.
We will describe a new method for identifying recent and ancient hybrids from the analysis of a single genome, as well as several surprising discoveries resulting from the application of this approach to a diverse array of plant species. We will show that hybridization is more frequent than previously believed, particularly in invasive species, and that circa 85% of polyploid species are allopolyploids. We will explore the roles of recent and ancient hybridization and polyploidy on diversification rates in plants. Lastly, we will discuss recent work in our lab on the genetic basis and evolutionary significance of heterosis and transgressive segregation in wild and domesticated sunflowers.