Origin of gynodioecy in Limnanthes: evidence from ecogeographic patterns of variation.

Evidence for hybrid origin of gene-cytoplasmic gynodioecy in Limnanthes douglasii is presented in terms of the parapatric distributions of putative parental taxa and the increased levels of genetic variation in gynodioecious populations. Attempts to produce gynodioecy through artificial hybridization between different accessions apparently failed due to the limited number of parental combinations used in making hybrids. Further studies are proposed on the hybrid origin model and on selective forces determining the fate of gynodioecy with its contributions to higher levels of hybridity and genetic variation.