We analyzed the population genetic structure of Euryale ferox Salisb. (Nymphaeaceae), an annual aquatic herb, to obtain information useful for conservation of this species. A total of 391 plants from 58 populations throughout Japan and four plants from a population in China were sampled and genotyped using eight microsatellite markers. Within- and among-population genetic diversity of E. ferox in Japan was basically low, with all eight microsatellite loci fixed to single alleles in many populations. However, multilocus genotypes including heterozygous loci were detected from three populations; these populations had inbreeding coefficients (F_<IS>) not equal to 1.0 and it is assumed that these multilocus genotypes are produced by outbreeding of genetically different individuals. Principal coordinate analysis (PCO) and population genetic structure analysis using INSTRUCT software uncovered at least two genetically distinct groups within Japanese E. ferox populations, neither of which had a simple geographical distribution pattern. This complex genetic structure may be the result of a random fixation of MLGs through genetic drift after habitat loss and by spatial and temporal admixture among populations through seed dispersal and seed banks.
Southern rear edge populations of cold-adapted plants at low latitudinal margins will probably be critical for determining species' responses to climate change. We focused on southern rear edge populations of an arctic-alpine plant, Dryas octopetala, in the high mountains of the Far East to assess genetic diversity and genetic structure by using allozyme variation and chloroplast DNA sequences. Allozyme data revealed low genetic diversity within populations (H_e = 0.003-0.144), but high genetic differentiation among populations (G_<ST> = 0.403), indicating characteristics of small and isolated populations that have persisted on mountain sky islands. The loss of genetic diversity was particularly pronounced in central Japan. On the basis of the cpDNA-haplotype distribution, the distinctive relationship between central Japan and not only northern Japan but also parts of Eurasia suggests that southernmost populations in the high mountains of central Japan are long-standing relicts of the Quaternary climate oscillations. Their refugial history therefore shaped the genetic diversity and genetic structure of the southern rear edge populations in Far East Asia.
Two strains previously identified as Chloromonas insignis, NIES-447 and ACOI-3241, and two new strains related to NIES-447 were examined using light microscopy. The molecular phylogeny of their 18S rRNA gene sequences were also examined, and their identifications are reassessed. The strains represent two independent species, both of which can be distinguished from Chloromonas insignis. Strain NIES-447 and the two new strains each have large, irregular atypical pyrenoids without associated starch granules. They are described here as Gloeomonas anomalipyrenoides Nakada et al. sp. nov. Strain ACOI-3241, which has small atypical pyrenoids on the tips of the chloroplast lobes, was identified as C. vernalis (Skuja) Nakada comb. nov. The identity of the three strains of G. anomalipyrenoides was verified by their identical ITS-2 rDNA sequences. Both G. anomalipyrenoides and C. vernalis of the clade Chloromonadinia in the Volvocales (Chlorophyceae) are closely related to other species of Gloeomonas and to C. kasaiae Matsuzaki, Nakada, Y. Hara & Nozaki, respectively.
Only triploid and tetraploid apogamous cytotypes have previously been reported for the fern Dryopteris chinensis (Dryopteridaceae). In this paper we report the discovery of a diploid sexual cytotype of D. chinensis. The geographical distribution of the sexual and apogamous types of the species in Japan and adjacent region was determined by counting the number of spores per sporangium in a large number of herbarium specimens from MAK and TNS. Apogamous plants were found to be the predominant type in Japan; the sexual type was restricted to Miyazaki, Oita, and Kumamoto prefectures in Kyushu, and Kochi Prefecture in Shikoku, Japan.
The Dryopteris varia complex (subg. Erythrovariae, sect. Variae Fraser-Jenk.) is an apogamous fern complex. Most species of the complex are apogamous triploids; Dryopteris saxifraga and D. varia, the only known diploid sexual cytotypes in the complex, are insufficient to account for the morphological and genetic variation within the complex. In this study, we describe a new diploid sexual species, Dryopteris protobissetiana K. Hori et N. Murak., from southern Yakushima, and discuss its morphological characteristics, reproductive mode, and chromosome number. Dryopteris protobissetiana is similar to D. bissetiana in having slightly bullate scales and a dark green lamina surface, but it differs in having flat, serrate margins at the apex of the upper pinnae. Dryopteris protobissetiana is a sexual diploid with 2n=82, and may be a source of the genetic variation in the apogamous complex.
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