Plant & Animal Genomes XIV Conference

January 14-18, 2006
Town & Country Convention Center
San Diego, CA

Genetic Divergence Of The Widespread Species Echinacea angustifolia Along A Climatic Gradient

David W. Still

  Department of Plant Science Cal Poly Pomona 3801 W Temple Avenue Pomona, CA 91768

Echinacea species, known collectively as purple coneflowers, are native to North America and have had a long history of use as a medicinal plant. Confusion has long existed in delimiting taxa within this species and we have provided a molecular assessment of genetic divergence within this genus. One species, Echinacea angustifolia, is particularly interesting because of its widespread geographic distribution and it is reported to have been the most used medicinal plant of the Plains Indians. We collected from populations along a 1500 km N-S climatic gradient to study patterns of genetic differentiation and the possible causes of microevolution within this species. Using AFLP we measured the patterns of divergence among populations and F_ST estimates indicated populations in Oklahoma and Kansas were the most divergent. About 60% of the genetic variation was found within populations, 20% among populations and the remaining 20% was partitioned among groups. Using partial Mantels tests to control for spatial autocorrelation, we determined genetic divergence fit a model of isolation-by-distance independent of the effects of annual mean ppt, but not from annual mean temperature and freeze-free days.