Flavone Variation and Subspecific Divergence in Phlox pilosa (Polemoniaceae)

Abstract

Flavone profile variation among 210 populations of Phlox pilosa substantially clarifies the history of subspecific divergence and range establishment in the species. Diagnostic profiles distinguish: 1) four of the five recognized subspecies, 2) two primary flavonoid lineages, one characterized by subsp. ozarkana and the other by subsp. detonsa, 3) a broad zone of detonsaozarkana intergradation but none between subsp. pilosa and subsp. detonsa, in the latter case contrary to expectations from morphology, and 4) two extremes of geographic variability within subspecies, either overall uniformity or a complex patchwork of sometimes regionalized profiles. Phenomenologically, the patterns of infraspecific flavone variation highlight a number of expected stages in the differentiation process leading to the interspecific flavonoid divergence generally observed in Phlox.