Using Phylogeny Reconstruction to Test Hypotheses of Hybrid Origin in Delphinium Section Diedropetala (Ranunculaceae)

One-hundred ITS rDNA and 32 trnL-F cpDNA sequences were used to reconstruct the phylogeny of 62 (of 67) species of Delphinium section Diedropetala to test the hypothesized hybrid origins of Delphinium gypsophilum and D. luteum. Delphinium gypsophilum has been proposed to be a hybrid derivative of D. recurvatum and D. hesperium ssp. pallescens; D. luteum is of putative hybrid origin between D. decorum and D. nudicaule. The nuclear and chloroplast sequence data were analyzed separately and, because there was no conflict, in combination. TrnL-F alone did not provide much resolution. The ITS data set and the combined ITS/trnL-F data set resolved several small clades. Delphinium luteum appears in a clade with both of its putative parents, and D. gypsophilum appears in a clade with D. recurvatum. In both cases, the sequence data are consistent with hybrid origin, but are also consistent with the putative hybrids being closely related to one or both of their proposed progenitors. Population-level data (allozymes, RAPDs, and AFLPs) support the latter hypothesis. Although our goal was not to resolve all relationships throughout sect. Diedropetala, the results provide initial information on subsectional relationships.