A karyological study on speciation of the Ixeris dentata complex
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概要
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Somatic chromosomes of three races of the Ixeris dentata complex such as subsp. nipponica (2n=14), subsp. dentata var. dentata (2n=21, 28), and var. albiflra f. amplifolia (2n=21, 28) and an endemic species of the Yakushima Is., I. stenophylla (2n=21) were morphologically examined. The chromosome complements were commonly classified into three different groups (a, b, and c), as follows ; 2n=14=2a+10b+2c in the diploid, 2n=21=3a+15b+3c in the triploid, and 2n=28=4a+20b+4c in the tetraploid. Furthermore, the a_2- and a_3-chromosome were commonly seen in all the taxa examined. These facts suggested that the morphological differentiations into the three chromosomal groups and those among the a-group chromosomes occurred in an ancestral plant or at early stage of the speciation of the I. dentata complex. The new finding of 2n=28 clones in subsp. dentata var. dentata and var. albiflora f. amplifolia suggested that a polyploid series (2n=14, 21, and 28) existed or had existed in all races being able to find out the 2n=21 cytotype at the present. The polyploid series might have occurred independently in each race from the other races. The 11 races of the I. dentata complex were classified into two different types, Dentata-type and Nipponica-type, in external morphology. This bio-classificational system was considered to be more accordant in a cytogenetical point of view. The chromosome number of 2n=21 and the karyotype in Ixeris stenophylla were reported here for the first time.
- 財団法人染色体学会の論文
著者
関連論文
- A karyotypical study in Commelina communis L. in the Korean Peninsula
- A karyological study on speciation of the Ixeris dentata complex