Potential for Ongoing Adaptation of a Native Prairie Plant
Rapid global change has raised questions about the capacity of species to persist under novel conditions. A population’s persistence depends on the distribution of fitness and the genetic differences responsible for fitness variation. Mean fitness is a measure of a population’s current adaptation to an environment. Additive genetic variance is an estimate of a population’s immediate potential to adapt. Statistical issues have hindered previous assessment of the additive genetic variance for fitness, but aster models with random effects provide a more robust means of calculation. Both mean fitness and additive genetic variance for fitness are unique to a given population in a given environment. Using pedigreed populations of Rudbeckia hirta (Asteraceae, Black Eyed Susan), planted in roadside common garden experimental plots, I aim to examine the current fitness and potential to increase fitness of multiple seed source populations in roadside environments.
One season of field data from two source populations has been collected to date. Mean fitness does not differ between site of seed origin (P=0.522). Additive genetic variance for fitness has not been detected. Additive genetic variance for fitness is calculated from the sire variance component in the random effects model. The sire variance component for one source population was estimated at 0, while the other population had a 95% confidence interval ranging from -0.007 to 0.052. R. hirta is a short-lived perennial plant, and no individual has yet flowered in this study. Differences could arise or be further erased throughout the lifespan of these individuals.