关键词: 昆虫, 数量变化, 神农架自然保护区

Abstract

Wild Cymbidium goeringii (Orchidaceae) plants in Hubei Province have become endangered due to over-harvesting and habitat fragmentation in recent years. The genetic diversity of 325 individuals from 11 populations in Hubei Province was investigated using inter-simple sequence repeat (ISSR) markers. As a re-sult, 127 bands were amplified by 11 informative and reliable primers, of which 112 were polymorphic loci. A relatively high level of genetic diversity was revealed: PPL=88.19%, H_e = 0.2628, H_o = 0.4037 (at species level); PPL = 63.06%，H_e = 0.1945, H_o = 0.2958 (at population level). A higher level of genetic differentia-tion was detected among populations with Nei's G_ST analysis and analysis of molecular variance (AMOVA; G_ST = 0.2440，F_ST = 0.2207). Some differentiation may result from habitat fragmentation and barriers to gene flow. UPGMA cluster analysis indicated that the five populations from Enshi region (BD, FBS, XE, MB, and LF) grouped together, whereas Dawu (DW) population clustered in an isolated clade. The Mantel test showed that genetic distance was positively correlated with geographical distance. Furthermore, the results showed that a mixed mating system was possibly the main factor influencing the genetic structure of this species. These results, combined with other information about C. goeringii, may provide a valuable basis for proposing conservation strategies. In situ conservation will be suitable for Laifeng (LF), Jingshan (JS), and Dawu (DW) populations with sufficient genetic diversity, while an ex situ strategy should be taken into consideration for Maoba and Xuanen populations, where only a few individuals are left.

Key words: insect, abundance, Shennongjia Natural Reserve