|其他摘要||The genus Craspedolobium (Tephrosieae, Fabaceae), with one species C. schochii Harms, is widely distributed in Yunnan, China. It was ever thought to be a Chinese endemic genus in the past decades, and played an important role in indicating the characteristics of Yunnan Plateau. However, according to the latest distribution data, Craspedolobium can not be considered a genus endemic to China any longer. After analyzing the relationship between the distribution of C. schochii and that of ancient planation surface in Yunnan, we found out that there is a correlation between them. In order to test its genetic diversity, genetic structure, and geographical differentiation, phylogeographical analysis based on DNA sequences was carried. The main results are as follows:
1. Biological habits and preliminary observation of pollination
C. schochii is a sun-adapted shrubby liana or small woody liana with altitudes ranging from 700 to 2500 m, and usually grows in the edge of forest and on roadsides. Sometimes it is noticeable to be a large woody liana in the forest. Flowers are purple or violet and glomerulate in mostly elongated racemes which are terminal and axillary near the tip of branches. Pod is dehiscent with a narrow wing on the ventral suture. Seeds are kidney-shaped and flat. The anthesis of one flower is 1.5─2.5 d. Four insects observed as flower-visitors are all in the Order Hymenoptera.
2. Unacceptability of its endemism to China
According to the latest literatures and our field investigations, Craspedolobium can not be accepted as a genus endemic to China any more. Its distribution has reached southwards to Burma, Thailand and Laos. The circumscription of plant genera endemic to China from the upcountry of China is rather stable .But as for the taxa distributed in Yunnan, especially those reached the national boundary, their endemism to China is questionable and needs to be carefully recognized. Some genera in such cases were temporarily recognized as endemic to China because of no distribution data available from neighbouring countries. The endemism of such Chinese plants is not unchangeable when new distribution data are available. Therefore, it is of great necessity to strengthen the cooperation with the neighboring countries for further investigations on the vegetation and flora in these regions.
C. schochii was found as a kind of large woody liana in some semi-humid evergreen broad-leaved forests in Yunnan, which is not consistent with the viewpoint in the past. Undoubtedly, Yunnan plateau is “Ecological Center” of C. schochii, and might be its “Diversity Center” as well.
3. Correlation between the distribution of C. schochii and Yunnan Ancient Planation Surface
It is well known that with the increase of latitude at which one species is distributed, the altitude will decrease. However, for C. schochii, the fact is inconsistent with this. There was a positive correlation between the latitude and altitude at which C. schochii is located, just like the distribution of Yunnan Ancient Planation Surface. So we considered that there is a correlation between the distribution of C. schochii and that of Yunnan Ancient Planation Surface. The difference between them is that the elevation of the Yunnan Ancient Planation Surface’s distribution trendline is larger than that of C. schochii. Our explanation for this phenomenon is that the distribution of species is determined by its ability and the way of adaption to the environment, moreover the adaption of plant always lags the geological change. Since the distribution pattern and the relationship with latitude and altitude of them are similar, we concluded that the distribution of C. schochii and the uplift of Yunnan Ancient Planation Surface are synchronous. On the other hand, the disintegration of Planation Surface has led to the altitude range at which C. schochii is distributed in any region where it appears. For example, the altitude at which it is distributed could be from 1950 m to 2330 m in Fangshan of Yongren, Yunnan.
4. Preliminary phylogeography
Based on atpB-rbcL sequence data of 123 individuals from 24 populations of C. schochii, the phylogeographical analysis was carried out, and the results are as follows: 1) C. schochii has high genetic differentiation (GST＝0.832, NST＝0.871) and moderate genetic diversity (HT＝0.663). 7 haplotypes were found in 24 populations, and there are 4 haplotypes in Central Yunnan, so the region may be “Diversity Center” of C. schochii. 2) When considering “Tanaka Line” as a boundary, there is a discrepancy of genetic structure on the two sides of the line. The Northeast populations have all the haplotypes, whereas the Southwest popultions have only 3 haplotypes. The factors which caused this discrepancy are: First, the uplifting of Planation Surface was greater in the North than in the South; second, the populations in Anninghe River valleys were affected by the Quaternary Glaciation; third, Dian-Qian-Gui region is noted for species richness and high speciation. 3) Based on the distribution of haplotype, the differentiation within C. schochii has no strict correlation with “Tanaka Line”.|