Allozyme Divergence in Coreopsis cyclocarpa (Compositae)

Abstract

Coreopsis cyclocarpa is a diploid, suffrutescent perennial occurring in the grasslands of high plateau regions of Mexico. The species consists of two allopatric varieties, var. pinnatisecta and the typical one. They are very similar morphologically and appear to differ only by a feature of the leaves. The two infraspecific taxa are highly interfertile. Electrophoresis was utilized to ascertain the amount of divergence between the varieties at 20 genetic loci coding for soluble enzymes. There is high genetic identity among populations of the same variety, with mean values of 0.98 for populations of var. cyclocarpa and 0.95 for var. pinnatisecta. When comparing mean identities for populations of the two varieties, the value is 0.75, indicating genetic divergence between the taxa. It is suggested that genetic differentiation between the two varieties is a reflection of the time they have been isolated.