Karyotype and cytogeography of the genus Heracleum (Apiaceae) in the Hengduan Mountains
Karyotype and cytogeography of the genus Heracleum (Apiaceae) in the Hengduan Mountains
复制标题
横断山伞形科伞形科植物的核型和细胞地理学
DOI：
10.1111/j.1759-6831.2009.00031.x
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发表时间：
2009-07-01
影响因子：
3.7
通讯作者：
Mang, Yu-Cheng
中科院分区：
文献类型：
--
作者：
Deng, Xian-Lan;He, Xing-Jin;Mang, Yu-Cheng
本文对中国横断山区独活属11种1变种34个居群的核型进行了研究。首次报道了三个种的染色体数目和核型，以及四倍体的莫伦多菲和亨瑞的染色体组型。横断山区的二倍体和四倍体植物组成了坎地兰、弗兰切蒂和金丝雀的种群。除4种独活属植物同时具有二倍体和四倍体核型外，其余种均为二倍体。所有的核型都属于Stebbins的2A型，除了甘蔗变种。Obtusifolium，属于2B；H.hemsleyanum和H.frchetii(Mt.杜鹃、稻城、四川、中国)，属于1A。核型不对称指数只有很小的差别，这表明它们与独活属物种有较近的亲缘关系，整个独活属的系统发育相对原始。形态特征较好的物种在核型结构上也较先进，核型进化顺序为1A->；2A->；2B。这一现象表明，横断山区分布的物种并没有完全分化，横断山是一个相对年轻和活跃的独角兽进化区域。多倍化可能是某些物种产生多样性的重要进化机制。该属的生物学属性、分布范围和地质历史都对多倍化或非整倍化的进化起到了促进作用。已知独活属植物的分布纬度从北到南降低，染色体数目、倍性水平和不对称结构呈增加趋势。在横断山区，这些趋势也很明显。最后，根据已有的细胞地理学数据，我们推测印度独活属中较高级的四倍体或非整倍体物种可能来源于分布在高加索地区和横断山区的早期双体物种。赫拉克朗的扩散是从欧亚大陆到印度的，因为这与喜马拉雅山脉通过构造运动而出现有关。因此，横断山不仅是独角兽物种多样性的中心，也是现代活跃物种形成的中心。
In the present study, the karyotypes of 34 populations belonging to 11 species and one variety of Heracleum from the Hengduan Mountains in China were examined. Chromosome numbers and the karyotypes of three species (H. souliei, H. kingdoni, and H. wenchuanense) are reported for the first time, as are the karyotypes of H. moellendorffii and H. henryi (tetraploid). Populations of H. candicans, H. franchetii, and H. kingdoni in the Hengduan Mountains were found to consist of a mixture of diploid and tetraplold plants. Except for four species of Heracleum, namely H. candicans, H. franchetii, H. henryi, and H. kingdoni, which have both diploid and tetraploid karyotypes, all other species of Heracleum are were found to be diploid. All karyotypes were found to belong to the 2A type of Stebbins, with the exception of H. candicans var. obtusifolium, which belongs to 2B, and H. hemsleyanum and H. franchetii (Mt. Dujuan, Daocheng, Sichuan, China), which belong to 1A. There was only a slight difference in the karyotype asymmetry index, which suggests a close kinship for species of Heracleum and that the entire phylogenetic development of Heracleum is relatively primitive. Species that exhibited advanced morphological features were also more advanced in karyotype structure, with the order of karyotype evolution being 1A -> 2A -> 2B. This phenomenon indicates that the species distributed in the Hengduan Mountains have not diverged completely and that the Hengduan Mountains are a relatively young and active area for the evolution of Heracleum. Polyploidization in Heracleum may be an important evolutionary mechanisms for some species, generating diversity. The biological attributes, distribution range, and the geological history of the genus have all played a part in accelerating the evolution through polyploidization or aneuploidization. It is known that as the distribution latitude of Heracleum decreases from north to south, the chromosome number, ploidy level, and asymmetry structure appear to increase. In the Hengduan Mountains, these tendencies are also evident. Finally, based on all the available cytogeographic data, we speculate that the more advanced tetraplont or aneuploid species of Heracleum in India may be derived from early diplont species that were distributed in the Caucasus region and Hengduan Mountains. The dispersal of Heracleum was from Eurasia to India, because this correlates with the emergence of the Himalayan Mountains through tectonic movement. Thus, the Hengduan Mountains are not only a center of diversity for Heracleum, but also a center of active speciation in modem times.