Phylogeographical studies of the genus Carex based on DNA sequences

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Caex L. is one of the largest genera of vascular plants and has more than 200 species in Japan. Carex has diffuse centromeric chromosomes and a remarkable aneuploid series ranging from n = 6 to n = 66. Four aneuploids (2n=18, 20, 24, 26) are reported in C. oxyandra. The phylogeographic pattern and genetic diversity of the widespread Japanese sedge were studied based on chloroplast DNA haplotypes and chromosomal variations. The geographical distribution of intraspecific aneuploids of C. oxyandra corresponded well with those of the haplotypes. The results of phylogeographical studies of C. oxyandra, C. kamagariensis, and C. laticeps suggest that the genetic diversity and chromosomal variations in these species may have originated from contractions and expansions of geographical ranges affected by Quaternary climatic oscillations.