The effect of geographic range and dichogamy on genetic variability and population genetic structure in Tricyrtis section Flavae (Liliaceae)

Populations of each of the four species of Tricyrtis sect. Flavae were samp led using enzyme electrophoresis to examine the effect of geographic range and dichogamy on the genetic diversity of the species. The most widespread species, T. nana, had the lowest level of genetic diversity at both the pop ulation and the species level. The depauperate genetic diversity at the pop ulation level of T. nana appears to result from the high self-fertilization of the species. The low genetic diversity at the species level of T. nana probably resulted from the bottleneck effect during the speciation process in which this species diverged from the progenitor species, T. flava. Genet ic differentiation among populations was high in both adichogamous T. nana and protandrous T. flava. High self-fertilization in T. nana and the coloni zing nature of T. flava are likely the main factors causing the differentia ted population genetic structure. In contrast to a previous study on chloro plast DNA (cpDNA) variation in Tricyrtis sect. Flavae, T. nana was most clo sely related to T. flava, which corresponds to the morphological resemblanc e of both species.