PHYLOGEOGRAPHY OF THE JAPANESE COMMON SEDGE, CAREX CONICA COMPLEX (CYPERACEAE), BASED ON CHLOROPLAST DNA SEQUENCE DATA AND CHROMOSOMAL VARIATION

Premise of the study : Genetic and chromosomal variations in plants are often reflected in the geographical distribution patterns. Therefore, identifying such phylogeographical patterns on population is important for understanding the process of plant diversification and speciation, and analyzing both molecular and cytological aspects is necessary. Methods : We investigated the phylogeographic pattern and genetic diversity of the widespread Japanese sedge, Carex conica complex, based on chloroplast DNA haplotypes and chromosomal variations. Key results : Sixteen distinct haplotypes were detected from 258 individuals in the C. conica complex inferred from the cpDNA sequences of intergenic spacer (IGS) between atpB and rbcL, IGS between trnT and trnL, trnL intron, and IGS between trnL and trnF. Most haplotypes showed distinct geographical structures. Phylogenetic analyses revealed two major clades, clades I and II, among 16 haplotypes of the complex. The haplotypes of clade I were mainly found in eastern Japan, while most haplotypes of clade II were found in western Japan. Four intraspecific aneuploids of 2n = 32, 34, 36, and 38, with forming normal bivalents in meiotic divisions, were also found in the complex. The geographical distribution of these intraspecific aneuploids corresponded well with those of the haplotypes. Conclusions : Our results suggest that the genetic diversity and chromosomal variations in the C. conica complex may have originated from contractions and expansions of geographical ranges affected by Quaternary climatic oscillations.