The Relationships of Two Ecologically Marginal, Sympatric Clarkia Populations

Abstract

A marginal population of C. unguiculata and a sympatric population called "Caliente" were compared by growing plants of the 2 types in the same pots. The 2 differ significantly in 1 qualitative tract and in 18 of the 22 quantitative morphological traits considered. They also differ significantly in 6 developmental traits relating to time of flowering, rate of flower opening, stigma receptivity, and ability of effect self-pollination. The 2 populations differ with respect to degree of chromosome re-patterning and are isolated by an apparently complete barrier to hybridization. "Caliente" is apparently adapted to the relatively hot, dry habitat by its more rapld development but C. unguiculata is more abundant. The differences between C. unguiculata and "Caliente" are remarkably parallel to differences between the former and 3 other species that have been derived from C. unguiculata, suggesting that "Caliente" may also have been derived from C. unguiculata.