Genetic diversity of widespread Ophiopogon intermedius (Liliaceae s.l.): a comparison with endangered O. xylorrhizus

Allozyme electrophoresis was used to examine the levels and distribution of genetic diversity on Ophiopogon intermedius, a widespread perennial species. Based on allozyme variation at 17 putative loci, high levels of genetic variability were detected with 82.4% of the loci being polymorphic. The mean expected heterozygosity within population (Hep) and within species (Hes) were 0.352 and 0.426, respectively. Differentiation among populations was detected with FST=0.143. The high levels of genetic diversity in O. intermedius in the present allozyme survey are consistent with the results from the study on morphological and chromosomal characteristics variation. The results from the comparison of the levels of genetic diversity between O. intermedius and O. xylorrhizus, an endangered congener, showed that the widespread O. intermedius maintained much higher levels of genetic diversity than O. xylorrhizus (P=46.2%, Hep=0.091, Hes=0.116; Ge, S., Zhang, D.M., Wang, H.Q., Rao, G.Y., 1997. Allozyme variation in Ophiopogon xylorrhizus: an extreme endemic species of Yunnan, China. Consvervation Biology 11, 562–565). The present study seemly confirmed the general opinion that the widespread species maintains higher levels of genetic diversity than its rare and endangered congener with similar life history traits, while the latter does not necessarily have absolutely low genetic variation. Genetic drift in small populations and inbreeding could have contributed to the relative low genetic variation and gene flow within and among populations of O. xylorrhizus compared with it widespread congener.