摘要:气候变化直接影响着物种的分布范围。了解气候变化对濒危物种分布区的影响，是开展保护生物学研究的基础。双花木属（Disanthus Maxim.） 1种1变种，隶属金缕梅科（Hamamelidaceae），为东亚特有濒危物种和典型的中-日间断分布成分，在研究东亚植物区系地理演化方面具有重要的科学价值。本研究基于双花木属植物19个当前居群分布点的气候变量，运用 MaxEnt模型预测双花木属植物在末次盛冰期（约22000年前）、当前（1950-2000年）和未来（2060-2080年）气候情景下的潜在分布区的结果显示，受试者工作特征曲线下的面积（AUC=0.9999±0.0001）接近于1，表明MaxEnt模型的预测准确度极高；气候变量贡献率和Jackknife检验评估的结果显示，制约双花木属植物分布的主导气候变量是最湿月降水量和最干月降水量。采用ArcGIS 10.0中的ArcToolbox空间分析工具定量分析比较双花木属的分布动态，基于生境稳定性（N_stab）、当前与其他时期分布区面积比（N_a）和扩张/收缩程度（N_e）的分析结果揭示，在双花木属植物进化过程中，分布范围经历了收缩过程；未来的温室气体排放量升高程度不同，其适生区呈现不同程度（30%-65%）收缩，特别是RCP 8.5气候情景下，我国武夷山山脉的潜在分布区有可能会丧失。探讨双花木属植物对不同时期气候变化的响应，重建冰期以来该属植物地理分布的变迁历史，分析限制其潜在地理分布的主导气候变量，可为双花木属植物保育措施的制定和东亚地区植物区系物种形成演化的研究提供理论参考。



Abstract:Rapid climate change has greatly contributed to the species distribution of Disanthus. Understanding the influence of climate change on the distribution of endangered species is essential for conservation biology. Disanthus Maxim., a genus that includes one species and one variety, is endemic to East Asia. It is the most basal and the oldest genus in Hamamelidaceae, and has a discontinuous distribution across China and Japan. This genus is significant for the study of the phylogeny and the biogeography of East Asia. In this paper, nineteen populations of Disanthus Maxim. were selected to study the potential distribution of this genus during current, Last Glacial Maximum, and future periods, for which the representative concentration pathways of greenhouse gases were 2.6, 4.5, 6.0, and 8.5, respectively. A high area under the receiver operating characteristic curve (AUC=0.9999±0.0001) indicated that the prediction accuracy of the MaxEnt model was very high. The precipitation of the wettest month and precipitation of the driest month were the dominant factors affecting the distribution of this genus. Quantitative analysis performed in ArcToolbox were used to compare the distribution dynamic of the genus. An analysis based on the habitat stability of the population (N_stab), the area ratio of the distribution area between Current and other periods (N_a), and the degree of expansion or contraction (N_e) showed that Disanthus Maxim. underwent contraction coupled with evolution. The suitable distribution area of Disanthus Maxim. will likely alter depending on increases in greenhouse gas emissions in the future. The potential contractions in the distribution of Disanthus Maxim. range from thirty to sixty five percent. It is likely that the Disanthus Maxim. population found in the Wuyishan Mountains would be lost under RCP 8.5, in particular. Predicting the potential distribution areas of this genus in different periods would be helpful to improve our understanding of how the genus responds to climate change and the restriction mechanisms of environmental variables on the potential distribution of the species. This study could provide a theoretical reference point for the establishment of conservation measures for Disanthus Maxim. and help the study of the formation and evolution of the flora of East Asia.





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