Cytological studies on the genus Holcoglossum (Orchidaceae) |
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| Authors: | XIAO-HUA JIN TING ZHANG ZHI-JIAN GU DE-ZHU LI |
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| Affiliation: | Herbarium (PE), Institute of Botany, Chinese Academy of Sciences, Nanxinchun 20, Beijing 100093, China;
Key Laboratory of Biodiversity and Biogeography, Kunming Institute of Botany, Chinese Academy of Sciences, Kunming 650204, China |
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| Abstract: | The karyotypes of ten species of Holcoglossum (Orchidaceae), a highly endangered and diversified genus from China, were investigated to study the infrageneric relationships, biogeography, and speciation patterns in the Hengduan Mountains. The karyotype formulae of the studied species are as follows: 2 n = 38 = 20m + 18sm in H. subulifolium , 2 n = 38 = 22m + 16sm in H. amesianum , 2 n = 38 = 26m + 12sm (6 SAT) in H. lingulatum , 2 n = 38 = 26m + 12sm in H. wangii , 2 n = 38 = 10m + 28sm in H. kimballianum , 2 n = 38 = 14m + 22sm + 2st in H. flavescens , 2 n = 38 = 24m + 12sm + 2st in H. rupestre , 2 n = 38 = 14m + 20sm + 4st in H. sinicum , 2 n = 38 = 16m + 14sm + 8st in H. weixiense , and 2 n = 76 in H. tsii . The karyotypes of two tropical species, H. amesianum and H. subulifolium , are the most primitive in the genus, whereas those of four temperate alpine species, H. sinicum , H. rupestre , H. weixiense , and H. flavescens , are more advanced. H. tsii is a tetraploid and H. rupestr e may be one of its ancestors. The low frequency of polyploidy in Holcoglossum in the Hengduan Mountains region supports the conclusion that chromosome stasis during rapid speciation is common there. © 2007 The Linnean Society of London. Botanical Journal of the Linnean Society , 2007, 154 , 283–288. |
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| Keywords: | biogeography chromosome stasis Hengduan Mountains karyotypes tetraploid |
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