Tadashi Yamashiro, Yoshinori Kaneshiro, Asuka Yamashiro and Masayuki Maki : The Genetic Diversity and Structure of the Feral Raccoon (Procyon lotor) Population in Shikoku Island, Japan, Mammal Study, Vol.47, No.3, 189-196, 2022.
Tadashi Yamashiro, Asuka Yamashiro, Michiyuki Maruoka, Tomiki Kobayashi and Masayuki Maki : Genetic Structure of a Rare Interspecific Hybrid of Vincetoxicum atratum and V. pycnostelma (Apocynaceae-Asclepiadoideae), Acta Phytotaxonomica et Geobotanica (APG), Vol.72, No.3, 227-239, 2021.
Shinji Fujii, Tadashi Yamashiro, Sachiko Horie and Masayuki Maki : Crassula peduncularis and C. saginoides (Crassulaceae), Newly Naturalized in Japan, and their Genetic Differences from C. aquatica, Acta Phytotaxonomica et Geobotanica (APG), Vol.70, No.2, 119-127, 2019.
(要約)
Recently, we found two species of <i>Crassula </i>newly introduced into central Japan. Based on their morphology, we identified them as <i>Crassula peduncularis </i>and <i>C. saginoides</i>, native to the New World. They closely resemble <i>C. aquatica</i>, which is indigenous to Japan. Here, we describe the morphological distinctions among the three species in detail. In addition, we examined genetic differences among the three species based on sequence variations in the nuclear ribosomal ITS region and three chloroplast intergenic regions. Although <i>C. saginoides </i>was considered to be an inland form of <i>C. aquatica </i>and had been treated as a synonym of <i>C. aquatica</i>, the degree of genetic differentiation was relatively large, suggesting that these two taxa should be considered to be independent species.
Tadashi Yamashiro, Ogawa Makoto, Asuka Yamashiro and Maki Masayuki : Natural hybridization between the endangered herb Artemisia gilvescens (Asteraceae) and the common congener, Artemisia indica var. maximowiczii in Japan, Acta Phytotaxonomica et Geobotanica (APG), Vol.69, No.2, 109-117, 2018.
Oike Akira, Watanabe Koichiro, Min Mi-Sook, Tojo Kaji, Kumagai Masahide, Kimono Yuya, Tadashi Yamashiro, Matsuo Takanori, Kodama Maho, Nakamura Yoriko, Notsu Maseru, Tochimoto Takeyoshi, Fujita Hiroyuki, Ota Maki, Ito Etsuro, Yasumasu Shigeki and Nakamura Masahisa : Origin of sex chromosomes in six groups of Rana rugosa frogs inferred from a sexlinked DNA marker, Journal of Experimental Zoology. Part A, Ecological and Integrative Physiology, Vol.327, No.7, 444-452, 2017.
(要約)
Each vertebrate species, as a general rule, has either the XX/XY or ZZ/ZW chromosomes by which sex is determined. However, the Japanese Rana (R.) rugosa frog is an exception, possessing both sex-determining combinations within one species, varying with region of origin. We collected R. rugosa frogs from 104 sites around Japan and South Korea and determined the nucleotide sequences of the mitochondrial 12S ribosomal RNA gene. Based on the sequences, R. rugosa frogs were divided into four groups from Japan and one from South Korea. The ZZ/ZW type is reportedly derived from the XX/XY type, although recently a new ZZ/ZW type of R. rugosa was reported. However, it still remains unclear from where the sex chromosomes in the five groups of this species were derived. In this study, we successfully isolated a sex-linked DNA maker and used it to classify R. rugosa frogs into several groupings. From the DNA marker as well as from nucleotide analysis of the promoter region of the androgen receptor (AR) gene, we identified another female heterogametic group, designated, West-Central. The sex chromosomes in the West-Central originated from the West and Central groups. The results indicate that a sex-linked DNA marker is a verifiable tool to determine the origin of the sex chromosomes in R. rugosa frogs in which the sex-determining system has changed, during two independent events, from the male to female heterogamety.
Asuka Yamashiro, Kanashiro Yoshinori, Yoichi Kawaguchi and Tadashi Yamashiro : Species, sex, and individual identification of Japanese serow (Capricornis crispus) and sika deer (Cervus nippon) in sympatric region based on the fecal DNA samples, Conservation Genetics Resources, Vol.9, No.2, 333-338, 2017.
Tadashi Yamashiro, Asuka Yamashiro, Masahito Inoue and Masayuki Maki : Genetic Diversity and Divergence in Populations of the Threatened Grassland Perennial Vincetoxicum atratum (Apocynaceae-Asclepiadoideae) in Japan., The Journal of Heredity, Vol.107, No.5, 455-462, 2016.
(要約)
We examined the genetic diversity and structure in populations of the endangered grassland herb Vincetoxicum atratum using 11 polymorphic microsatellite loci. Although the populations were small and disconnected, our molecular data indicated that the species maintains relatively high levels of genetic diversity and connectivity among populations. Population clustering analyses detected 2 to 3 clusters and most of the populations of V. atratum comprised admixture of these genetic clusters. These admixtures likely formed during the process of colonizing habitats that had been disturbed by human activities. However, STRUCTURE clustering detected low-admixtures in populations occurring in rocky maritime sites, which may not be suitable for agriculture/rangeland activities. High genetic diversity and population connectivity suggested that loss of the remaining populations by grassland reduction might be an immediate threat for this species. Small grasslands populations managed by local farmers need appropriate conservation practices. Although our results showed genetic diversity and gene flow among populations of V. atratum were high, it is possible that this resulted from the historical continuous distribution of the species. To examine this hypothesis, further periodical monitoring of the genetic diversity and the genetic differentiation for the species is needed for a conservation action of the species.
Yue Li, Fumito Tada, Tadashi Yamashiro and Masayuki Maki : Long-term persisting hybrid swarm and geographic difference in hybridization pattern: genetic consequences of secondary contact between two Vincetoxicum species (ApocynaceaeAsclepiadoideae), BMC Evolutionary Biology, Vol.16, 20, 2016.
(要約)
During glacial periods, glacial advances caused temperate plant extirpation or retreat into localized warmer areas, and subsequent postglacial glacial retreats resulted in range expansions, which facilitated secondary contact of previously allopatric isolated lineages. The evolutionary outcomes of secondary contact, including hybrid zones, dynamic hybrid swarm, and resultant hybrid speciation, depends on the strengths of reproductive barriers that have arisen through epistatic and pleiotropic effects during allopatric isolation. The aim of this study was to demonstrate refugia isolation and subsequent secondary contact between two perennial Asclepioid species and to assess the genetic consequences of the secondary contact. We modeled the range shift of two ecologically distinct Vincetoxicum species using the species distribution model (SDM) and assessed the genetic consequences of secondary contact by combining morphological and genetic approaches. We performed morphometric analysis (592 individuals) and examined 10 nuclear microsatellites (671 individuals) in V. atratum, V. japonicum, and putative hybrid populations. Multivariate analysis, model-based Bayesian analysis, and non-model-based discriminant analysis of principal components confirmed the hybridization between V. atratum and V. japonicum. High pollen fertility and a lack of linkage disequilibrium suggested that the hybrid populations may be self-sustaining and have persisted since V. atratum and V. japonicum came into contact during the post-glacial period. Moreover, our findings show that the pattern of hybridization between V. atratum and V. japonicum is unidirectional and differs among populations. Geographically-isolated hybrid populations exist as genetically distinct hybrid swarms that consist of V. atratum-like genotypes, V. japonicum-like genotypes, or admixed genotypes. In addition, Bayesian-based clustering analysis and coalescent-based estimates of long-term gene flow showed patterns of introgressive hybridization in three morphologically 'pure' V. japonicum populations. In this study, we demonstrated that climatic oscillations during the Quaternary period likely led to species range shift and subsequently secondary contact. Hybrid populations may be self-sustaining and have persisted since V. atratum and V. japonicum came into contact during the post-glacial period. Pattern of hybridization between V. atratum and V. japonicum is unidirectional and differs among populations. We concluded that these differences in the genetic consequences of secondary contact are caused by historical colonization processes and/or natural selection.
Yuki Matsumoto, Yu-ten Ju, Tadashi Yamashiro and Asuka Yamashiro : Evidence of pre-introduction hybridization of Formosan sika deer (Cervus nippon taiouanus ) on Okinoshima, Wakayama Prefecture, Japan, based on mitochondrial and nuclear DNA sequences, Conservation Genetics, Vol.16, No.2, 497-502, 2015.
Chung Yoon Mi, Nason D. John, López-Pujol Jordi, Tadashi Yamashiro, Yang Bo-Yun, Luo Yi-Bo and Chung Gi Myong : Genetic consequences of fragmentation on populations of the terrestrial orchid Cymbidium goeringii, Biological Conservation, Vol.170, 222-231, 2014.
Chung Yoon Mi, Moon Myung-Ok, López-Pujol Jordi, Maki Masayuki, Tadashi Yamashiro, Yukawa Tomohisa, Sugiura Naoto, Lee Yung-I and Chung Gi Myong : Was Jeju Island a glacial refugium for East Asian warm-temperate plants? Insights from the homosporous fern Selliguea hastata (Polypodiaceae), American Journal of Botany, Vol.100, No.11, 2240-2249, 2013.
(要約)
We posed two hypotheses for broad scenarios of postglacial recolonization of Korea by the warm-temperate vegetation: (1) that extant Korean populations are derived from a single refugium, or (2) that they are derived from multiple refugia. We chose a homosporous fern typical of East Asian warm-temperate vegetation, Selliguea hastata, to test which of the two scenarios is more likely and to check whether Japan contained putative glacial refugia. Using 16 allozyme loci, we obtained genotypes of 756 individuals from 20 populations, representative of the whole distribution area in Korea (including Jeju Island), Japan, and Taiwan. We assessed genetic variability within and among populations, Wright's F-statistics, and conducted analysis of molecular variance, model-based Bayesian clustering, and bottleneck tests. We found no allozyme variation within populations of S. hastata in mainland Korea, whereas genetic polymorphism was detected for populations from Jeju Island, Japan (in particular a population from southeastern Shikoku), and Taiwan. The levels of inbreeding within populations were high, consistent with the potential of S. hastata for intragametophytic selfing. Data on allelic richness together with Bayesian clustering methods suggest a pattern of postglacial recolonization of mainland Korea from a single refugium, probably located either on Jeju Island or in Japan. Jeju Island should merit the highest priority for conservation biogeography, as it played a role as a Quaternary refugium for arctic-alpine, boreal, temperate as well as warm-temperate plants, as suggested here.
(キーワード)
Bayes Theorem / Conservation of Natural Resources / Electrophoresis / Genetic Variation / Inbreeding / Islands / Isoenzymes / Japan / Molecular Sequence Data / Phylogeny / Plant Proteins / Polypodiaceae / Republic of Korea / Sequence Analysis, DNA / Taiwan
Tadashi Yamashiro, Asuka Yamashiro, Ikumi Dohzono and Masayuki Maki : Development of Microsatellite Markers for Isodon longitubus (Lamiaceae), Applications in Plant Sciences, Vol.1, No.10, 1300028, 2013.
(要約)
· Microsatellite markers were developed for Isodon longitubus to study the natural hybridization of the species and its congeners. · A total of 10 primer sets were developed for I. longitubus. From the initial screening, all of 10 loci were polymorphic with five to 19 alleles per locus in the Mt. Ishizuchi population, whereas nine loci were polymorphic with two to 12 alleles per loci in the Toon population. Although one locus was monomorphic at one population, the observed and expected heterozygosity values estimated from 34 I. longitubus samples ranged from 0.273 to 1.000 and from 0.483 to 0.918, respectively. Six primer sets could amplify all three species examined in this study (I. inflexus, I. japonicus, and I. shikokianus). · The 10 microsatellite markers developed here will be useful in analyzing the population genetic structure of I. longitubus and in studying the natural hybridization between Isodon species.
Asuka Yamashiro, Mahito Kamada and Tadashi Yamashiro : A comparative study of the fecal characters of Japanese serow (Capricornis crispus) and sika deer (Cervus nippon), Mammal Study, Vol.38, No.2, 117-122, 2013.
Asuka Yamashiro, Tadashi Yamashiro and Yoichi Tateishi : Isolation and characterization of micro satellite markers for Canavalia cathartica and C. lineata (Fabaceae), Applications in Plant Sciences, Vol.1, No.1, 1200111, 2013.
Tadashi Yamashiro, Asuka Yamashiro, Ogawa Makoto, Kurosaki Nobuhira, Kobayashi Tomiki and Maki Masayuki : High population genetic diversity and regional differentiation in the endemic Vincetoxicum katoi-yamanakae complex (Apocynaceae; Asclepiadoideae) in Japan, Acta Phytotaxonomica et Geobotanica (APG), Vol.63, No.1, 29-40, 2012.
(要約)
We examined morphological differentiation and allozyme diversity in nine populations of Vincetoxicum katoi and its close relative V. yamanakae. Although, V. yamanakae has been distinguished from V. katoi in having a larger corolla and gynostegium, the principal component analysis based on 12 floral and three leaf characters did not support the distinction of the two taxa. The six allozyme loci examined revealed that population of V. katoi and V. yamanakae maintained high genetic diversity (P=72.1, A=2.40, h=0.313). The nine populations were clustered into three regions (Kanto-Tokai; middle Kiniki; and Kii-Shikoku) based on genetic differences, contradicting the current taxonomic treatment. Considering the evidence, it is appropriate to treat V. yamanakae as a synonym of V. katoi. The high genetic differentiation among regions suggested that disjunct distribution of the V. katoi-V. yamanakae complex might reflect the persistence of refugia since the last glacial period. In particular, the middle Kinki (Hyogo) population is located outside of known evergreen forest refugia, suggesting that it might have survived during the glacial period within cooler vegetative zones, such as in temperate forests, whereas the populations on the Pacific-side retreated to warm-temperature coastal refugia.
Tadashi Yamashiro and Kobayashi Tomiki : Genetic diversity in the threatened local endemic plant Arisaema minus (Araceae), Acta Phytotaxonomica et Geobotanica (APG), Vol.61, No.3, 117-122, 2011.
(要約)
The genetic diversity and genetic structure of the locally endemic Arisaema minus was examined using allozyme polymorphisms. Arisaema minus is restricted to Hyogo Prefecture in western Honshu, Japan. The Red List of Japan treats it as "vulnerable". To determine the genetic diversity of the species, 274 individuals from six populations were sampled. Genetic diversity at 10 allozyme loci was relatively high at both the population and species level, and comparable to previously reported species of Japanese Arisaema species having wider distribution ranges. Although the western and eastern Hyogo populations are disjunct, very low genetic differentiation was observed among the six populations (Gst=0.06). The genetic data suggest that the risk of rapid extinction of A. minus is quite low. The eastern Hyogo populations, however, have lower genetic diversity than those in western Hyogo and are threatened by habitat destruction caused by human activities, therefore placing them at greater risk of extinction. Periodic monitoring of both the demography and genetic variation in the eastern populations is needed.
(キーワード)
Arisaema minus / genetic diversity / local endemic
Asuka Yamashiro, Tadashi Yamashiro, Baba Minoru, Endo Akira and Mahito Kamada : Species identification based on the faecal DNA samples of the Japanese serow (Capricornis crispus), Conservation Genetics Resources, Vol.2, No.1, 409-414, 2010.
Maki Masayuki, Kokubugata Goro and Tadashi Yamashiro : Lack of allozyme diversity in populations of the endangered perennial Senecio scandens (Asteraceae) in Japan: comparison with a population in Taiwan, Vol.58, No.1, 39-42, 2010.
24.
Masayuki Maki, Tadashi Yamashiro, Ikumi Dohzono and Kazuo Suzuki : Molecular phylogeny of Isodon (Lamiaceae) in Japan using chloroplast DNA sequences: recent rapid radiations or ancient introgressive hybridization?, Plant Species Biology, Vol.25, No.3, 240-248, 2010.
Maki Masayuki, Matsumura Shun'ichi and Tadashi Yamashiro : Allozyme diversity and history of distribution expansion in the martime perennial plant Hedyotis strigulosa (Rubiaceae), distributed over the wide latitudes in the Japanese Archipelago, Biological Journal of the Linnean Society, Vol.93, No.4, 679-688, 2008.
Asuka Yamashiro and Tadashi Yamashiro : Utilization on extrafloral nectaries and fruit domatia of Canavalia lineata and C. cathartica (leguminosae) by ants, Arthropod-Plant Interactions, Vol.2, No.1, 1-8, 2008.
Tadashi Yamashiro, Asuka Yamashiro, Jun Yokoyama and Masayuki Maki : Morphological aspects and phylogenetic analyses of pollination systems in the Tylophora-Vincetoxicum complex (Apocynaceae-Asclepiadoideae) in Japan, Biological Journal of the Linnean Society, Vol.93, No.2, 325-341, 2008.
Kamada Takuro, Tadashi Yamashiro and Maki Masayuki : Intraspecific morphological and genetic differentiation in Scrophularia grayana (Scrophulariaceae), Journal of Plant Research, Vol.120, No.3, 437-443, 2007.
(要約)
Scrophularia grayana, which is distributed throughout northern Japan and Sakhalin, and its locally endemic variety var. grayanoides, have been examined morphometrically and genetically. Principal-component analysis using a total of 26 morphological characteristics revealed that these taxa are morphologically differentiated, but that the difference is not distinct. These two taxa have the same number of chromosomes in the somatic cells, 2n = 94, suggesting that ploidal level difference is not relevant to their divergence. The distributions of the taxa are adjoining in the north of Japanese mainland Honshu. Nevertheless, principal-coordinate analysis using putative 112 ISSR loci indicated they are genetically very distinct. Many taxon-specific alleles were found, and many of the alleles were fixed in each taxon. This genetic information suggests that a relatively long time has passed since the taxa became differentiated and that gene flow has rarely occurred between them, although morphological similarity has been maintained, probably because of natural selective forces.
(キーワード)
Flowers / Genetic Variation / Geography / Japan / Plant Leaves / Scrophularia / Species Specificity
Tadashi Yamashiro, Kazuo Suzuki and Maki Masayuki : Chromosome Numbers of Isodon (Lamiaceae) in Japan, Acta Phytotaxonomica et Geobotanica (APG), Vol.56, No.3, 241-246, 2005.
(要約)
Somatic chromosome numbers were counted in seven species and six varieties of Isodon occurring in Japan. All of the taxa had 2n=24 chromosomes, indicating that they are diploid. For all taxa except I. umbrosus var. hakusanensis and I. japonicus, chromosome numbers are reported here for the first time. The results suggest that diversification in Japanese taxa of Isodon has occurred at the diploid level, even though some reticulation had been suggested by a preliminary molecular study.
Tadashi Yamashiro and Masayuki Maki : A comparative study of the reproductive character and genetic diversity of an autogamous Tylophora matsumurae and its progenitor Tylophora tanakae (Apocynaceae-Asclepiadoideae), Plant Systematics and Evolution, Vol.256, No.1, 55-67, 2005.
Tadashi Yamashiro, Tatsuya Fukuda, Jun Yokoyama and Masayuki Maki : Molecular phylogeny of Vincetoxicum (Apocynaceae-Asclepiadoideae) based on the nucleotide sequences of cpDNA and nrDNA, Molecular Phylogenetics and Evolution, Vol.31, No.2, 689-700, 2004.
(要約)
Molecular phylogenetic analyses of Vincetoxicum and Tylophora (Apocynaceae-Asclepiadoideae) were conducted based on the nucleotide sequences of cpDNA (two intergenic spacers of trnL (UAA)-trnF (GAA) and psbA-trnH and three introns, i.e., atpF, trnG (UCC) and trnL (UAA)), and nrDNA (ITS and ETS regions). Our phylogenetic analysis revealed two monophyletic groups; one consisted of seven taxa of Tylophora and Vincetoxicum inamoenum, Vincetoxicum magnificum and Vincetoxicum macrophyllum (Clade I) and the other consisted of 17 accessions of Vincetoxicum (Clade II). The monophyly of the genus Vincetoxicum was not supported. Although many nucleotide substitutions were observed in Clade I, the genetic differentiation within Clade II was small. Low genetic diversification but considerable morphological divergence suggests that the species in Clade II had undergone rapid diversification. Although most species in Clade I have tiny flowers, those in Clade II have larger and more nectariferous ones. Thus, we hypothesized that the rapid morphological radiation in Clade II may have been due to the gaining of floral characters such as large flowers and large amounts of nectar corresponding to diverse pollinators.
Tadashi Yamashiro, Jun Yokoyama and Masayuki Maki : Two new species of Vincetoxicum (Apocynaceae-Asclepiadoideae) from Japan, Acta Phytotaxonomica et Geobotanica (APG), Vol.55, No.1, 1-8, 2004.
(要約)
Two new species, Vincetoxicum izuense and V. hoyoense, are described here. Vincetoxicum izuense is a twining perennial herb on rocky beaches and on the margins of thickets near the sea and is endemic to the southern Izu Peninsula. It resembles V. sublanceolatum and V. japonicum, but V. izuense is distinguished from them by the leaves, follicles and trichomes on the lower surface of the leaves. Vincetoxicum hoyoense is a large, perennial, twining herb on rocks and on the margins of thickets facing the sea and is endemic to the area around the Bungo Channel. Vincetoxicum hoyoense resembles V. japonicum f. puncticulatum and V. sublanceolatum, but V. hoyoense can be distinguished from them by the larger, elliptic or ovate leaf blades with shallowly cordate base and the longer corolla lobes. Although V. hoyoense also resembles V. izuense in flower, morphology and leaf shape, V. hoyoense is easily distinguished from it by the large ovate or elliptic leaves with shallowly cordate base and the large corollas.
(キーワード)
Bungo Channel / Izu Peninsula / new species / Vincetoxicum
Tadashi Yamashiro, Yoichi Tateishi, Tetsuo Denda, Masatsugu Yokota and Masyuki Maki : Transference of Cynanchum matsumurae T. Yamaz. to Tylophora (Asclepiadaceae), The Journal of Japanese Botany, Vol.78, No.6, 349-354, 2003.
Masayuki Maki, Tadashi Yamashiro and Shun-ichi Matsumura : High levels of genetic diversity on island populations of the island endemic Suzukia luchuensis (Labiatae), Heredity, Vol.91, No.3, 300-306, 2003.
(要約)
Genetic diversity and genetic differentiation within and among island populations was examined by allozyme electrophoresis in Suzukia luchuensis (Labiatae), which is endemic to four of the Ryukyu Islands, southern Japan, and one island near Taiwan. Intrapopulation allozyme diversity was very low in all the four Ryukyu Islands, probably due to the effects of random drift in small populations. In contrast, genetic diversity at the species level was high, possibly because of an ancient origin of populations and/or multiple colonization of the species on different islands. Genetic differentiation among the overall populations was high (G(ST)=0.863), while gene flow (Nm) as estimated from allozyme frequency data was 0.041, suggesting that its occurrence among populations is highly restricted. Hierarchical analysis of genetic differentiation indicated that a high proportion of the total allelic variance is attributed to variation among islands, corresponding to the fact that several alleles were fixed on only one island. However, intraisland genetic differentiation was small on all islands except Yonaguni Island, where S. luchuensis is relatively widely distributed. Most diversity was thus due to differences among islands.
Tadashi Yamashiro, Yoichi Tateishi and Masayuki Maki : Vincetoxicum yonakuniense, a new combination of Asclepiadaceae and its new distribution record on Senkaku Island, Ryukyu Archipelago, Acta Phytotaxonomica et Geobotanica (APG), Vol.54, No.1, 31-36, 2003.
(要約)
Cynanchum yonakuniense, a perennial twining herb, endemic to Yonaguni Island, the Ryukyu Archipelago has never been recorded since its original materials collected there. We rediscovered it on the island and moreover found a herbarium specimen of the species on Senkaku Islands in the same archipelago. In this paper we added the morphologies of root, fruit and seed to the description of this species. On the basis of morphological re-examinations, we propose a new combination Vincetoxicum yonakuniense.
(キーワード)
Asclepiadaceae / Cynanchum yonakuniense / new combination / Ryukyu Archipelago