Study On Conservation Biology Of Endangered Changium Smyrnioides Endemic To China

Changium smyrnioides Wolff, a species of monotypic genus in the family Apiaceae, is an endangered herbaceous perennial plant. It is endemic to China, and is distributed only in fragments in Zhejiang, Anhui, Jiangsu, Jiangxi, and Hubei Provinces. Seven populations throughout the entire distribution of the species were chosen to measure the genetic diversity and genetic structure by morphological and karyotypic and allozyme and RAPD and ISSR analysis. The pollination biology, plant anatomy and seed biology were investigated. The phylogenetic relationship of Changium smyrnioides and Chuanminshen was reconstructed by ITS and morphological analysis. Based on these results , the endangered mechanism and protection strategies were discussed. The results could be summarized as follows.1. Changium smyrnioides is inclined to grow in a range of habitats, for example along rocky hillside in subtropical broadleaf forest where soil is deeper and moister than in the other habitats. The content of N, P and K is high and the pH was about 6.5 in soil. The study of population biology indicated the species in spatial pattern was of clump distribution. We think that the deforestation and habitat fragmentation are the important endangered reasons of Changium smyrnioides.2, It is found that in the natural populations of Changium smyrnioide the recruitment of young seedlings is rare, although seed set is high. The anatomy experiment indicated that the embryo within mature seeds were at a primary stage. Seed germination experiment showed that the afterripening process of seeds ended after 4~6 months and seeds could successfully germinate in appropriate condition. In nature environment, the seeds of Changium smyrnioide can't retain the physiological activity over a year.The seed banks of Changium smyrnioide are non-persistent. The study also revealed the incoordination between the afterripening of seed and the raining season of East China resulted in low ratio of seed germination.Thus, water and temperature are the important factors to restrict the afterripening and germination of seeds and seedling growth. The study of pollination biology indicated that the average ratio of seed set was about 72.5% in natural populations and only 28.5% by sheathing inflorescence test, and 13. 7% in the close greenhouse. So we can draw the conclusion that self-pollination maybe exisisted in the breeding system of Changium smyrnioides in stress. Insects played an important role in sexual reproduction. Although the breeding system of Changium smyrnioides was dominantly xenogamous. However,some species of beetles often visitedflowers of the same individual and frequent occurrence of pollination within a short distance would result in high inbreeding coefficient.3. Nested analysis of variance indicated that about 83% of the morphological variability of carpadelium was attributed to the differentiation among the populations and the remaining 17% resided within the populations. The shape of fruit tended to become longer, thicker and rounder from southwestern area to eastern area in the distribution. The number of vjttae was 3 in each groove and 4 ~5 in commissura. The type of cotyledon varied among populations. The seedlings of populations in the south of the Yangtze River were monocotyledonous, but the seedlings of populations in the north of the Yangtze River were dicotyledonous. The selection forces are. strong on the morphological characters.4. The karyotypic analysis of Changium smyrnioides indicated that the chromosomal number was stable (2n=20) in all populations. Karyotypes of the populations were all "2A" type. Karyotypical polymorphism was showed as the chromosomal heterozygosity, and position shift of the satellite.5. Genetic diversity of 4 populations was analysed with starch gel electrophoresis. The proportion of polymorphic loci (PPB) is 73.68% at species level. Genetic diversity within 4 populations was relatively low with the proportion of polymorphic loci (PPB) ranging from 19% to 42.9%, average number of alleles per locus (...