Onagraceae as a model experimental system
Johnson, Marc .
From micro- to macroevolution: the contribution of Onagraceae to a modern synthesis of evolutionary ecology.
Species in the genus Oenothera (Ongaraceae), or evening primroses, were among the earliest models for the study of genetics, evolution biology and systematics. Here I describe how the resources provided by a century of research on this system have allowed us to address modern questions in evolutionary ecology. At the microevolutionary scale, we are examining whether there is a dynamic feedback between the ecology and evolution of plant-herbivore interactions. Our field experiments show that the native plant, common evening primrose (Oenothera biennis), contains heritable genetic variation for most traits, and that herbivores impose natural selection on many of these traits. Using theory and an experimental evolution approach in the field, we find that natural selection on life-history traits causes rapid genetic and phenotypic evolution within plant populations over just three generations. In turn, this evolution feeds back to influence the abundance and diversity of herbivore populations that specialize on O.biennis. We have also scaled up to the macroevolutionary scale to understand how repeated losses of meiotic recombination and segregation (i.e.functional asexuality) across the Onagreae clade have influenced the evolution and ecology of evening primroses and their interactions with mutualists(pollinators) and parasites (herbivores and pathogens). We find that there have been numerous transitions between sexual and functionally asexual reproduction,and the repeated loss of recombination and segregation is associated within creased speciation rates, and surprisingly, recombination and segregation can be regained once lost. Transitions to functional asexuality are also associated with numerous ecological and evolutionary consequences, compared to sexual lineages. For example, functionally asexual lineages occur at higher latitudes,invest less resources in flowers to attract pollinators, exhibit decreased resistance to generalist herbivores and exhibit slower rates of adaptive molecular evolution in genes critical in defenses against pathogens. These results illustrate how Oenothera can serve as a model to answering biological problems at the nexus of ecology and evolution.
Log in to add this item to your schedule
1 - University of Toronto, Mississauga, Biology, Mississauga ON, ON, L5L 1C6, CANADA
Presentation Type: Symposium or Colloquium Presentation
Location: Lenox Room/Chase Park Plaza
Date: Wednesday, July 13th, 2011
Time: 4:15 PM