Uniformity of karyotypes in Ligularia (Asteraceae: Senecioneae), a highly diversified genus of the eastern Qinghai-Tibet Plateau highlands and adjacent areas
Uniformity of karyotypes in Ligularia (Asteraceae: Senecioneae), a highly diversified genus of the eastern Qinghai-Tibet Plateau highlands and adjacent areas
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DOI：
10.1111/j.1095-8339.2003.00225.x
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发表时间：
2004-03-01
影响因子：
2.4
通讯作者：
Liu, JQ
中科院分区：
文献类型：
--
作者：
Liu, JQ
橐吾属是青藏高原东部及其邻近地区的一个高度多样化的属，被选为一个合适的主题，在染色体水平上研究这一“热点”地区的物种形成模式。本文对14种23个居群的染色体数目和核型进行了研究，其中大部分为本区特有种。所有物种的基数x = 29得到确认。黄帚橐吾具有二倍体和三倍体细胞型，2n = 58和87。其他物种只有二倍体，2n = 58。任何种内所有居群的核型，以及跨越大部分组和覆盖大部分形态范围的所有种的核型彼此非常相似，根据Stebbin分类法属于2A型。这种核型也在其近缘种中发现，例如Cremanthanus，Ligulariopsis，Parasenecio和Sinacalia。结果表明，橐吾属及其近缘种的染色体数目从2n = 60减少到58，并存在核型变异。这样的染色体模式与少数多倍体推断，在二倍体水平的核型结构的变化似乎是在这个组和同域物种形成的染色体进化的主要特征，通过杂交和多倍体化在其物种多样性中发挥了次要作用。(C)2004年伦敦林奈学会，
Ligularia, a highly diversified genus in the eastern Qinghai-Tibet Plateau and adjacent areas, was chosen as a suitable subject in which to study speciation patterns in this 'hot spot' area at the chromosomal level. Chromosome numbers and karyotypes were studied in 23 populations of 14 species, most of which are endemic to this area. The basic number x = 29 was confirmed for all species. Ligularia virgaurea was found to have diploid and triploid cytotypes, 2n = 58 and 87. Other species are only diploid, with 2n = 58. The karyotypes of all populations within any species, and all species spanning most sections and covering most of the morphological range in Ligularia, are very similar to each other, belonging to type 2A according to Stebbin's classification. This karyotype was also found in its close allies, e.g. Cremanthodium, Ligulariopsis, Parasenecio, and Sinacalia. Aneuploid reduction of chromosome number from 2n = 60 to 58 and karyotypic variation was found in Ligularia and its allies. Such a chromosomal pattern with few polyploids infers that variation of karyotype structure at the diploid level seems to be the predominant feature of chromosomal evolution in this group and sympatric speciation via hybridization and polyploidization has played a minor role in its species diversity. (C) 2004 The Linnean Society of London,