Poster: Late and Moved Abstracts

Abs # 943: Genetic variation of Echinacea angustifolia along a climatic gradient.

Presenter:	Still, David W, dwstill@csupomona.edu
Authors	Still, David W (A)   Aoyama, Natsuyo  (A)   Kim, Du-Hyun  (B)
Affiliations:	(A): California State Polytechnic University, Pomona (B): National Horticultural Research Institute, South Korea

We investigated genetic differentiation among populations of the widespread species Echinacea angustifolia among a 1500 km N-S cline of North America. Our objectives were to determine if the population genetic differentiation could be explained by an isolation by distance model or by associations with climatic parameters known to affect plant growth and survival. Using AFLP markers, we established patterns of population genetic differentiation among ten populations collected from North Dakota to Oklahoma. A total of 1290 fragments were scored using 6 EcoRI / MseI and 3 PstI / MseI primer combinations. The PstI / MseI combinations produced significantly fewer fragments, but a larger percentage was unique compared to EcoRI / MseI markers. Using estimates of F_ST, populations in Oklahoma and southern Kansas were identified as most diverse. Both the neighbor joining tree and principal coordinate analysis clustered the populations in a N-S spatial orientation. Most (60%) of the genetic variation was found within a population, approximately 20% was found among groups, and the remaining 20% among populations. Significant support was found for the isolation by distance model and each climatic parameter. Of particular interest was the finding that annual mean precipitation and freeze free days were highly significant when the closely related outgroup E. sanguinea was included. We conclude that the Echinacea angustifolia populations have been intact for a relatively long period of time having diverged from an earlier and rapid radiation event. The suitability of AFLP for population differentiation studies and the choice of restriction enzymes used in AFLP are discussed.