Comparisons of Genetic Diversity in the EndangeredAdenophora lobophyllaand Its Widespread Congener,A. potaninii

Abstract

Abstract:Starch‐gel electrophoresis was used to examine the levels and distribution of genetic diversity in twoAdenophoraspecies: the narrow endangeredAdenophora lobophyllaand its widespread congener,A. potaninii. Based on allozyme variation at 18 putative loci, we measured high levels of genetic variability both in the endangered and the widespread species, with 83.3% of the loci being polymorphic. The mean expected heterozygosity within populations ( Hep ) and within species ( Hes ) were 0.234 and 0.244 forA. potaniniiand were as high as 0.210 and 0.211 forA. lobophylla. There was higher differentiation among populations inA. potaninii( FST= 0.155) than inA. lobophylla( FST= 0.071). The high levels of genetic diversity in the present allozyme survey are consistent with the morphological variation observed in these species and may be attributed to high outcrossing rates in theAdenophoraspecies. In addition,A. lobophyllawas identified as a distinct species on the basis of Nei’s genetic distances and thus should be given a high priority for protection. It is noteworthy that the endangeredA. lobophyllamaintains much higher genetic diversity than most endemic or narrowly distributed plant species in spite of its restricted distribution. We hypothesize thatA. lobophyllahas become endangered for ecological and stochastic reasons, including habitat destruction or environmental changes, mud slides, and human disturbance such as grazing and mowing. Consequently, habitat protection is of particular importance for conserving this endangered species.