研究者詳細 - 三村　真紀子

論文 - 三村　真紀子

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Genomic Introgression in the Hybrid zones at the Margins of the Species' Range Between Ecologically Distinct Rubus Species 査読

Makiko Mimura, Zhenxing Tang, Shuji Shigenobu, Katsushi Yamaguchi, Tetsukazu Yahara

Ecology and Evolution 14 ( 11 ) e70476 2024年11月

担当区分：筆頭著者,　責任著者記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Wiley

ABSTRACT

Populations in extreme environments at the margins of a species' range are often the most vulnerable to climate change, but they may also experience novel evolutionary processes, such as secondary contact and hybridization with their relatives. The range overlap resulting from secondary contact with related species that have adapted to different climatic zones may act as corridors for adaptive introgression. To test this hypothesis, we examined the hybrid zones along the altitude of two closely related Rubus species, one temperate and the other subtropical species, at their southern and northern limits on Yakushima Island, Japan. Genomic cline analysis revealed non‐neutral introgression throughout the genome in both directions in the two species. Some of these genomic regions involve gene ontology terms related to the regulation of several biological processes. Our niche modeling suggests that, assuming niche conservatism, the temperate species are likely to lose their suitable habitat, and the backcrossed hybrids with the subtropical species are already expanding upslope on the island. Adaptive introgression through the hybrid zone may contribute to the persistence and expansion of the species in the southernmost and northernmost populations.

DOI： 10.1002/ece3.70476

Genetic diversity in the traditional cultivars and wild ancestor of near-threatened Japanese iris (Iris ensata Thunb.) 査読

Makiko Mimura, Marina Takeuchi, Takayuki Kobayashi, Shun K. Hirota, Yoshihisa Suyama, Hirofumi Yamaguchi, Toshihito Tabuchi

Conservation Genetics 25 ( 5 ) 1079 - 1086 2024年7月

担当区分：筆頭著者,　責任著者記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Springer Science and Business Media LLC

Abstract

Wild relatives of cultivars are crucial sources of genetic variation for further enhancement, yet they face potential threats due to contemporary environmental changes. Iris ensata var. spontanea, a wild progenitor of the Japanese iris cultivars (I. ensata var. ensata), is extensively cultivated in Japanese gardens, is distributed across mesic meadows and wetlands in Japan and East Asia. This species is currently threatened owing to habitat loss linked to land use alterations. We assessed genetic diversity and phylogenetic relationships in 32 wild accessions and the 14 principal Edo Group of Japanese iris cultivars, originally bred during the Edo period (1600–1868). In the phylogenetic tree, the cultivars formed a cluster with low inbreeding coefficients, suggesting a singular origin and interbreeding between the genetically distinct accessions. Conversely, wild accessions exhibited greater overall genetic diversity and higher inbreeding coefficients than cultivars, indicating frequent inbreeding within divergent natural populations. Our findings highlight the distinct genetic reservoirs of both wild accessions and Edo cultivars, although the former may face inbreeding challenges. Urgent conservation action is needed to ensure the genetic diversity of wild populations as natural resources.

DOI： 10.1007/s10592-024-01625-7

その他リンク： https://link.springer.com/article/10.1007/s10592-024-01625-7/fulltext.html

Plant characteristics drive ontogenetic changes in herbivory damage in a temperate forest 査読

Hiroko Kurokawa, Michio Oguro, Sakino Takayanagi, Masahiro Aiba, Rei Shibata, Makiko Mimura, Hiroshi Yoshimaru, Tohru Nakashizuka

Journal of Ecology 110 ( 11 ) 2772 - 2784 2022年9月

Phylogenetic inferences using nuclear ribosomal ITS and chloroplast sequences provide insights into the biogeographic origins, diversification timescales and trait evolution of Rubus in the Japanese Archipelago 査読

Satoshi Kikuchi, Makiko Mimura, Naohiro Naruhashi, Suzuki Setsuko, Wajiro Suzuki

Plant Systematics and Evolution 308 ( 3 ) 20 2022年6月

Phylogenetic signal in the topographic niche of trees: Current and historical significance of habitat structure on the species arrangement pattern within East Asian rugged forests 査読

Ryo Kitagawa, Makiko Mimura, Akira S. Mori, Akiko Sakai

Ecological Research 35 ( 4 ) 613 - 624 2020年7月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Wiley

Topography often promotes habitat heterogeneity and is a major factor in fine-grained changes in vegetation. Especially in temperate mountainous regions of East Asia, the distribution of tree species is largely explained by topographic niche differentiation. Because species niche is at least partially a historical product through the evolution of functional traits, phylogenetic signals are expected in the topographic arrangement pattern of species, although this has not been fully investigated. Thus, we examined common temperate trees in a 306 ha watershed on Mt Tanzawa, central Japan. The topographic niche position of each species was explained with two principal component analysis (PCA) axes, which aligned with the topographic structure of the watershed. High scores on PC1 reflected lower elevations, steeper slopes and nearby valleys. Higher scores on PC2 indicated thicker soil, more south-facing slopes, slighter slope inclinations and nearby valleys. The former indicated the species were aligned on a habitat gradient of land-surface instability, for which the gradient is typical under the current geological conditions. The latter indicated that a niche axis for resource availability relating to water, nutrients and light or heat existed. A phylogenetic signal, identified by Pagel's lambda and the Mantel test, was detected for PC2 scores. However, the species arrangement along PC1 was independent of phylogeny. Our results suggested that the topographic niche of tree species in this area is caused by both relatively recently derived traits regarding adaptation to unstable land surfaces and conservative traits derived through plant evolution.

DOI： 10.1111/1440-1703.12110

その他リンク： https://onlinelibrary.wiley.com/doi/full-xml/10.1111/1440-1703.12110

Ambiguous species boundaries: Hybridization and morphological variation in two closely relatedRubusspecies along altitudinal gradients 査読

Makiko Mimura, Mihoko Suga

Ecology and Evolution 10 ( 14 ) 7476 - 7486 2020年7月

担当区分：筆頭著者,　責任著者記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：WILEY

Although hybridization frequently occurs among plant species, hybrid zones of divergent lineages formed at species boundaries are less common and may not be apparent in later generations of hybrids with more parental-like phenotypes, as a consequence of backcrossing. To determine the effects of dispersal and selection on species boundaries, we compared clines in leaf traits and molecular hybrid index along two hybrid zones on Yakushima Island, Japan, in which a temperate (Rubus palmatus) and subtropical (Rubus grayanus) species of wild raspberry are found. Leaf sinus depth in the two hybrid zones had narrower clines at 600 m a.s.l. than the molecular hybrid index and common garden tests confirmed that some leaf traits, including leaf sinus depth that is a major trait used in species identification, are genetically divergent between these closely related species. The sharp transition in leaf phenotypic traits compared to molecular markers indicated divergent selection pressure on the hybrid zone structure. We suggest that species boundaries based on neutral molecular data may differ from those based on observed morphological traits.

DOI： 10.1002/ece3.6473

進化を考慮した保全生態学の確立と生態系管理に向けて査読

門脇浩明, 山道真人, 深野祐也, 石塚航, 三村真紀子, 西廣淳, 横溝裕行, 内海俊介

保全生態学研究 25 ( 2 ) 1933 - 234 2020年

Phylogeny and trait variation of Japanese Rubus subgenus Ideaobatus 査読

Okada, A, Kikuchi, S, Hoshino, Y, Kunitake, H, Mimura, M

Scientia Horticulturae 264 109150 2020年

Understanding and monitoring the consequences of human impacts on intraspecific variation 査読

Makiko Mimura, Tetsukazu Yahara, Daniel P. Faith, Ella Vazquez-Dominguez, Robert I. Colautti, Hitoshi Araki, Firouzeh Javadi, Juan Nunez-Farfan, Akira S. Mori, Shiliang Zhou, Peter M. Hollingsworth, Linda E. Neaves, Yuya Fukano, Gideon F. Smith, Yo-Ichiro Sato, Hidenori Tachida, Andrew P. Hendry

Evolutionary Applications 10 ( 2 ) 121 - 139 2017年2月

担当区分：筆頭著者,　責任著者記述言語：英語出版者・発行元：WILEY

Intraspecific variation is a major component of biodiversity, yet it has received relatively little attention from governmental and nongovernmental organizations, especially with regard to conservation plans and the management of wild species. This omission is ill-advised because phenotypic and genetic variations within and among populations can have dramatic effects on ecological and evolutionary processes, including responses to environmental change, the maintenance of species diversity, and ecological stability and resilience. At the same time, environmental changes associated with many human activities, such as land use and climate change, have dramatic and often negative impacts on intraspecific variation. We argue for the need for local, regional, and global programs to monitor intraspecific genetic variation. We suggest that such monitoring should include two main strategies: (i) intensive monitoring of multiple types of genetic variation in selected species and (ii) broad-brush modeling for representative species for predicting changes in variation as a function of changes in population size and range extent. Overall, we call for collaborative efforts to initiate the urgently needed monitoring of intraspecific variation.

DOI： 10.1111/eva.12436

Historical Relationships Among Wild Boar Populations of the Ryukyu Archipelago and Other Eurasian regions, as Inferred from Mitochondrial Cytochrome b Gene Sequences 査読

Saka Yoshikawa, Makiko Mimura, Shin Watanabe, Liang-Kong Lin, Hidetoshi Ota, Yasushi Mizoguchi

Zoological Science 33 ( 5 ) 520 - 526 2016年10月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：ZOOLOGICAL SOC JAPAN

The Ryukyu wild boar (Sus scrofa riukiuanus) is an endemic, morphologically defined subspecies of the Eurasian wild boar (S. scrofa) found on five islands of the Ryukyu Archipelago (a group of small islands stretching from mainland Japan to Taiwan). Two hypothetical scenarios have been proposed regarding the origin of the current Ryukyu wild boar populations: 1) natural dispersal and 2) transportation and subsequent release by prehistoric humans. To test these two hypotheses, we compared the mitochondrial cytochrome b gene sequence (1140 base pairs) in 352 individual wild boar samples that included representatives of all five insular populations of the Ryukyu wild boar and populations of other conspecific subspecies in insular East and Southeast Asia and the Eurasian Continent. A total of 68 haplotypes were recognized, of which 12 were unique to the Ryukyu wild boar populations. The results of Bayesian phylogenetic analyses supported monophyly of the five Ryukyu populations (posterior probability value of 92), confirming the validity of the subspecies as a natural group. Coalescent analysis estimated the divergence times between the Ryukyu wild boar and the other conspecific subspecies as 144-465 thousand years ago (Kya), with a 95% HPD (highest posterior density) range of 51-837 Kya, and with no significant migration. Taking the broadly accepted date of initial human migration to the Ryukyus (no earlier than 50 Kya) into consideration, our results strongly suggest that the ancestral form of the Ryukyu wild boar first entered the Ryukyu Archipelago by natural dispersal prior to the arrival of prehistoric humans.

DOI： 10.2108/zs160025

キイチゴたちが屋久島で出会うとき：気候変動と遺伝的交流

三村真紀子

屋久島学 2 97 - 99 2015年11月

Topographic patterns in the phylogenetic structure of temperate forests on steep mountainous terrain 査読

Ryo Kitagawa, Makiko Mimura, Akira S. Mori, Akiko Sakai

AOB PLANTS 7 2015年

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：OXFORD UNIV PRESS

In rugged terrain subject to active geomorphological processes, the species composition of forest communities changes along topographic gradients over short distances. However, the phylogenetic structure of forests on rugged terrain has rarely been examined. Understanding such structures provides insight into community assembly rules dependent on local environmental conditions. To this end, we tested the topographic trends of measurements of phylogenetic community structure [net relatedness index (NRI) and nearest taxon index] in a catchment covered by temperate forests with complex relief in Japan. We found that phylogenetic structure changed from over-dispersion to clustering with increasing slope inclination, change of slope aspect from south to north and decreasing soil depth. This result suggested that environmental filtering tended to restrict community composition at relatively stressful sites, whereas species interaction functioned more strongly at relatively stress-free sites. Relatively stressful sites were characterized by early-successional species that tended to assemble in certain phylogenetic clades, whereas highly competitive late-successional species associated with lower NRI at relatively stress-free sites. However, despite this significant topographic tendency, phylogenetic community structures were not statistically different from random assumptions in most plots. This obscuration of the phylogenetic structures at the plot level could be interpreted as species adapting to disturbances because they were abundant in this catchment. Accordingly, we suggest that a stochastic process was also important for this community at the plot level, although biotic and abiotic environmental filtering controlled the vegetation structure in the catchment, where disturbances occur frequently because of geomorphological mountain denudation processes owing to active crustal movements and abundant rainfall.

DOI： 10.1093/aobpla/plv134

Asymmetric gene flow and the distribution of genetic diversity in morphologically distinct Abies mariesii populations in contrasting eco-habitats 査読

Shenhua Qian, Waka Saito, Makiko Mimura, Shingo Kaneko, Yuji Isagi, Eri Mizumachi, Akira S. Mori

PLANT ECOLOGY 215 ( 12 ) 1385 - 1397 2014年12月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：SPRINGER

The steep and complex topography in high-elevation mountains usually generates heterogeneous habitats, where reproductive isolation in spatially discrete populations, such as unsynchronized flowering, likely occurs. Therefore, genetically differentiated populations in some cases can be expected. Patterns of genetic variation and directions of gene flow among discrete populations could hold crucial information for a better understanding of population genetic structures in heterogeneous habitats. In this study, we examined the local-scale genetic structure and gene flow patterns among Abies mariesii populations in a heterogeneously snowy subalpine ecosystem. We found that A. mariesii populations, though spatially discrete and undergoing strong habitat heterogeneity, are less likely to be genetically differentiated. Gene flow was biased toward the moorlands, and compared to the forest populations, the genetic diversity in the moorland populations was found to be significantly higher, suggesting that the moorlands could serve as sinks of genetic diversity for A. mariesii. Finally, we quantified the morphological variation of A. mariesii and discovered that being able to adjust tree morphology in contrasting eco-habitats may strengthen the competitiveness of A. mariesii. This may also make a tangible contribution to the maintenance of populations in contrasting habitats.

DOI： 10.1007/s11258-014-0395-y

Range shift and introgression of the rear and leading populations in two ecologically distinct Rubus species 査読

Makiko Mimura, Misako Mishima, Martin Lascoux, Tetsukazu Yahara

BMC EVOLUTIONARY BIOLOGY 14 209 2014年10月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：BIOMED CENTRAL LTD

Background: The margins of a species' range might be located at the margins of a species' niche, and in such cases, can be highly vulnerable to climate changes. They, however, may also undergo significant evolutionary changes due to drastic population dynamics in response to climate changes, which may increase the chances of isolation and contact among species. Such species interactions induced by climate changes could then regulate or facilitate further responses to climatic changes. We hypothesized that climate changes lead to species contacts and subsequent genetic exchanges due to differences in population dynamics at the species boundaries. We sampled two closely related Rubus species, one temperate (Rubus palmatus) and the other subtropical (R. grayanus) near their joint species boundaries in southern Japan. Coalescent analysis, based on molecular data and ecological niche modelling during the Last Glacial Maximum (LGM), were used to infer past population dynamics. At the contact zones on Yakushima (Yaku Island), where the two species are parapatrically distributed, we tested hybridization along altitudinal gradients.
Results: Coalescent analysis suggested that the southernmost populations of R. palmatus predated the LGM (similar to 20,000 ya). Conversely, populations at the current northern limit of R. grayanus diverged relatively recently and likely represent young outposts of a northbound range shift. These population dynamics were partly supported by the ensemble forecasting of six different species distribution models. Both past and ongoing hybridizations were detected near and on Yakushima. Backcrosses and advanced-generation hybrids likely generated the clinal hybrid zones along altitudinal gradients on the island where the two species are currently parapatrically distributed.
Conclusions: Climate oscillations during the Quaternary Period and the response of a species in range shifts likely led to repeated contacts with the gene pools of ecologically distinct relatives. Such species interactions, induced by climate changes, may bring new genetic material to the marginal populations where species tend to experience more extreme climatic conditions at the margins of the species distribution.

DOI： 10.1186/s12862-014-0209-9

A multi-year assessment of the environmental impact of transgenic Eucalyptus trees harboring a bacterial choline oxidase gene on biomass, precinct vegetation and the microbial community 査読

Taichi Oguchi, Yuko Kashimura, Makiko Mimura, Xiang Yu, Etsuko Matsunaga, Kazuya Nanto, Teruhisa Shimada, Akira Kikuchi, Kazuo N. Watanabe

TRANSGENIC RESEARCH 23 ( 5 ) 767 - 777 2014年10月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：SPRINGER

A 4-year field trial for the salt tolerant Eucalyptus globulus Labill. harboring the choline oxidase (codA) gene derived from the halobacterium Arthrobacter globiformis was conducted to assess the impact of transgenic versus non-transgenic trees on biomass production, the adjacent soil microbial communities and vegetation by monitoring growth parameters, seasonal changes in soil microbes and the allelopathic activity of leaves. Three independently-derived lines of transgenic E. globulus were compared with three independent non-transgenic lines including two elite clones. No significant differences in biomass production were detected between transgenic lines and non-transgenic controls derived from same seed bulk, while differences were seen compared to two elite clones. Significant differences in the number of soil microbes present were also detected at different sampling times but not between transgenic and non-transgenic lines. The allelopathic activity of leaves from both transgenic and non-transgenic lines also varied significantly with sampling time, but the allelopathic activity of leaves from transgenic lines did not differ significantly from those from non-transgenic lines. These results indicate that, for the observed variables, the impact on the environment of codA-transgenic E. globulus did not differ significantly from that of the non-transformed controls on this field trial.

DOI： 10.1007/s11248-014-9809-9

Biodiversity only makes sense in the light of evolution 査読

R. Geeta, Lucia G. Lohmann, Susana Magallon, Daniel P. Faith, Andrew Hendry, Keith Crandall, Luc de Meester, Campbell O. Webb, Anne-Helene Prieur-Richard, Makiko Mimura, Elena Conti, Joel Cracraft, Felix Forest, Carlos Jaramillo, Michael Donoghue, Tetsukazu Yahara

JOURNAL OF BIOSCIENCES 39 ( 3 ) 333 - 337 2014年6月

Standing variation boosted by multiple sources of introduction contributes to the success of the introduced species, Lotus corniculatus 査読

M. Mimura, K. Ono, K. Goka, T. Hara

BIOLOGICAL INVASIONS 15 ( 12 ) 2743 - 2754 2013年12月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：SPRINGER

Although ecological differences between native and introduced ranges have been considered to drive rapid expansion of invasive species, recent studies suggest that rapid evolutionary responses of invasive species to local environments may also be common. Such expansion across heterogeneous environments by adaptation to local habitats requires genetic variation. In this study, we investigated the source and role of standing variation in successful invasion of heterogeneous abiotic environments in a self-incompatible species, Lotus corniculatus. We compared phenotypic and genetic variation among cultivars, natives, and introduced genotypes, and found substantial genetic variation within both native and introduced populations. Introduced populations possessed genotypes derived from both cultivars and native populations, and had lower population differentiation, indicating multiple sources of introduction and population admixture among the sources in the introduced range. Both cultivars and introduced populations had similarly outperforming phenotypes on average, with increased biomass and earlier flowering compared with native populations, but those phenotypes were within the range of the variation in phenotypes of the native populations. In addition, clinal variation within introduced populations was detected along a climatic gradient. Multiple introductions from different sources, including cultivars, may have contributed to pre-adaptive standing variation in the current introduced populations. We conclude that both introduction of cultivar genotypes and natural selection in local environments contributed to current patterns of genetic and phenotypic variation observed in the introduced populations.

DOI： 10.1007/s10530-013-0488-x

Global legume diversity assessment: Concepts, key indicators, and strategies 査読

Tetsukazu Yahara, Firouzeh Javadi, Yusuke Onoda, Luciano Paganucci de Queiroz, Daniel P. Faith, Darien E. Prado, Munemitsu Akasaka, Taku Kadoya, Fumiko Ishihama, Stuart Davies, J. W. Ferry Slik, Tingshuang Yi, Keping Ma, Chen Bin, Dedy Darnaedi, R. Toby Pennington, Midori Tuda, Masakazu Shimada, Motomi Ito, Ashley N. Egan, Sven Buerki, Niels Raes, Tadashi Kajita, Mohammad Vatanparast, Makiko Mimura, Hidenori Tachida, Yoh Iwasa, Gideon F. Smith, Janine E. Victor, Tandiwe Nkonki

TAXON 62 ( 2 ) 249 - 266 2013年4月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：INT ASSOC PLANT TAXONOMY-IAPT

While many plant species are considered threatened under anthropogenic pressure, it remains uncertain how rapidly we are losing plant species diversity. To fill this gap, we propose a Global Legume Diversity Assessment (GLDA) as the first step of a global plant diversity assessment. Here we describe the concept of GLDA and its feasibility by reviewing relevant approaches and data availability. We conclude that Fabaceae is a good proxy for overall angiosperm diversity in many habitats and that much relevant data for GLDA are available. As indicators of states, we propose comparison of species richness with phylogenetic and functional diversity to obtain an integrated picture of diversity. As indicators of trends, species loss rate and extinction risks should be assessed. Specimen records and plot data provide key resources for assessing legume diversity at a global scale, and distribution modeling based on these records provide key methods for assessing states and trends of legume diversity. GLDA has started in Asia, and we call for a truly global legume diversity assessment by wider geographic collaborations among various scientists.

Colonization of vegetation-rich moraines and inference of multiple sources of colonization in the High Arctic for Salix arctica 査読

Makiko Mimura, Akira S. Mori, Masaki Uchida, Hiroshi Kanda

CONSERVATION GENETICS 14 ( 1 ) 223 - 229 2013年2月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：SPRINGER

Vegetation-rich patches in the High Arctic may serve as a significant source for vegetation reconstruction in the climate changes. Diversity and colonization, however, of such potential source populations in the High Arctic has rarely been studied. We examined chloroplast sequence variation in Salix arctica, a key species in the Canadian High Arctic, from four adjacent glacial moraines of differing ages on Ellesmere Island, Canada, as well as two other populations located at the center and southern end of the species' range. The estimated ages of the moraines varied from 35,000 to 250 years old. The older moraine populations showed higher within-population genetic variation compared with the other moraine populations, which is generally attributed to differences in establishment age associated with plant densities among moraines. The moraines with smaller plant density had lower genetic diversity and had no private haplotypes, indicating the local population size and genetic diversity may not be recovered within a few thousand years. This suggests seed dispersal at a local scale may be limited even in species with high velocity of seed dispersal, and that High Arctic vegetation-rich patches may serve as significant source populations for sustaining local genetic diversity. In addition, the three regions we observed comprised an evolutionarily distinct lineage and significant population differentiation. This implies multiple sources for the colonization during the most recent deglaciation, resulting in the current wide distribution. Local as well as range-wide processes of colonization would be essential to understand vegetation responses in High Arctic to the environmental changes.

DOI： 10.1007/s10592-012-0413-3

Genetic and phenotypic variation in Lotus japonicus (Regel) K. Larsen, a model legume species 査読

Makiko Mimura

Canadian Journal of Plant Science 93 ( 3 ) 435 - 444 2013年

記述言語：英語掲載種別：研究論文（学術雑誌）

Lotus japonicus is a model legume species with more than 90% of its gene space determined
however, its ecological and evolutionary background is little known. The genetic and phenotypic variation of this model species was investigated within the Japanese Archipelago, where it exists in various climates and has experienced repeated vegetative shifts in conjunction with historical climate changes, using nuclear microsatellite loci and common garden experiments. The partial Mantel test was performed to detect the influence of phylogeographic effects on phenotypic variation among accessions along environmental gradients. Western Japan showed more complex genetic population structures than northern Japan, which may reflect past population dynamics. The total biomass demonstrated clinal variation with a climatic variable (ClimatePC). The trend was significant in a partial Mantel test when controlling for genetic distance, which is independent of the environmental distance. This suggests adaptive divergence within the Japanese Archipelago. With highly accessible genome information, L. japonicus appears to be a promising species for future ecological and evolutionary studies.

DOI： 10.4141/CJPS2012-097

Local adaptation at the range peripheries of Sitka spruce 査読

M. Mimura, S. N. Aitken

JOURNAL OF EVOLUTIONARY BIOLOGY 23 ( 2 ) 249 - 258 2010年2月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：WILEY-BLACKWELL PUBLISHING, INC

High-dispersal rates in heterogeneous environments and historical rapid range expansion can hamper local adaptation; however, we often see clinal variation in high-dispersal tree species. To understand the mechanisms of the species' distribution, we investigated local adaptation and adaptive plasticity in a range-wide context in Sitka spruce, a wind-pollinated tree species that has recently expanded its range after glaciations. Phenotypic traits were observed using growth chamber experiments that mimicked temperature and photoperiodic regimes from the limits of the species realized niche. Bud phenology exhibited parallel reaction norms among populations; however, putatively adaptive plasticity and strong divergent selection were seen in bud burst and bud set timing respectively. Natural selection appears to have favoured genotypes that maximize growth rate during available frost-free periods in each environment. We conclude that Sitka spruce has developed local adaptation and adaptive plasticity throughout its range in response to current climatic conditions despite generally high pollen flow and recent range expansion.

DOI： 10.1111/j.1420-9101.2009.01910.x

我々は「生態リスク」とどう向き合うのか?

森章, 三村真紀子, 黒川紘子

日本生態学会誌 60 ( 3 ) 323 - 325 2010年

分布域のダイナミクス--シトカトウヒの分布拡大と局所適応招待査読

三村真紀子

林木の育種 236 ( 236 ) 1 - 6 2010年

Mycorrhizal colonization of transgenic Eucalyptus camaldulensis carrying the mangrin gene for salt tolerance 査読

Kipkorir E. Lelmen, Xiang Yu, Akira Kikuchi, Takayoshi Shimazaki, Makiko Mimura, Kazuo N. Watanabe

PLANT BIOTECHNOLOGY 27 ( 4 ) 339 - 344 2010年

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：JAPANESE SOC PLANT CELL & MOLECULAR BIOLOGY

Transgenic products and the creation of new organisms with innovative transgenic traits generally raise risk assessment concerns because of potential risks to nontarget organisms. Cartagena Protocol on Biosafety and Japanese government regulations require scientific environmental risk assessments of living modified organisms prior to release to avoid adverse effects on the environment. Soil microorganisms, such as the arbuscular mycorrhizal fungi, aid in plant nutrient acquisition and protection from environmental stresses such as salt stress. In this study, we used a salt-tolerant transgenic Eucalyptus camaldulensis transformed with the mangrin gene from a mangrove plant and evaluated the interactions between environmental stress-tolerant transgenic plants and arbuscular mycorrhizal fungi. Our results indicated that these transformants were substantially equivalent to nontransformants in terms of arbuscular mycorrhizal fungi colonization under both saline and nonsaline conditions, and that the arbuscular mycorrhizal fungi colonization could potentially enhance the salt tolerance of the transgenic plant.

DOI： 10.5511/plantbiotechnology.27.339

Comparison of contemporary mating patterns in continuous and fragmented Eucalyptus globulus native forests 査読

Makiko Mimura, Robert C. Barbour, Brad M. Potts, Rene E. Vaillancourt, Kazuo N. Watanabe

MOLECULAR ECOLOGY 18 ( 20 ) 4180 - 4192 2009年10月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：WILEY-BLACKWELL

While habitat fragmentation is a central issue in forest conservation studies in the face of broad-scale anthropogenic changes to the environment, its effects on contemporary mating patterns remain controversial. This is partly because of the inherent variation in mating patterns which may exist within species and the fact that few studies have replication at the landscape level. To study the effect of forest fragmentation on contemporary mating patterns, including effective pollen dispersal, we compared four native populations of the Australian forest tree, Eucalyptus globulus. We used six microsatellite markers to genotype 1289 open-pollinated offspring from paired fragmented and continuous populations on the island of Tasmania and in Victoria on mainland Australia. The mating patterns in the two continuous populations were similar, despite large differences in population density. In contrast, the two fragmented populations were variable and idiosyncratic in their mating patterns, particularly in their pollen dispersal kernels. The continuous populations showed relatively high outcrossing rates (86-89%) and low correlated paternity (0.03-0.06) compared with the fragmented populations (65-79% and 0.12-0.20 respectively). A greater proportion of trees contributed to reproduction in the fragmented (de/d >= 0.5) compared with the continuous populations (de/d = 0.03-0.04). Despite significant inbreeding in the offspring of the fragmented populations, there was little evidence of loss of genetic diversity. It is argued that enhanced medium-and long-distance dispersal in fragmented landscapes may act to partly buffer the remnant populations from the negative effects of inbreeding and drift.

DOI： 10.1111/j.1365-294X.2009.04350.x

Genetic variation of chloroplast DNA in Zingiberaceae taxa from Myanmar assessed by PCR-restriction fragment length polymorphism analysis 査読

D. Ahmad, A. Kikuchi, S. A. Jatoi, M. Mimura, K. N. Watanabe

ANNALS OF APPLIED BIOLOGY 155 ( 1 ) 91 - 101 2009年

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：WILEY-BLACKWELL PUBLISHING, INC

We examined genetic variation in 22 accessions belonging to 11 species in four genera of the Zingiberaceae, mainly from Myanmar, by PCR-restriction fragment length polymorphism analysis to investigate their relationships within this family. Two of 10 chloroplast gene regions (trnS-trnfM and trnK2-trnQr) showed differential PCR amplification across the taxa. Restriction enzyme digestion of the PCR products revealed interspecific variability. The restriction patterns were used to classify the regions as either highly conserved or variable across the taxa. None of the regions was highly conserved across the four genera, and the level of conservation varied. The gene region trnS-trnfM appeared to display interspecific variability among most of the species. However, the relative efficiency of different restriction enzymes depended on the gene regions and genera investigated. Cluster analysis revealed interspecific discrimination among the taxa. The two Curcuma species (Curcuma zedoaria and Curcuma xanthorrhiza) appeared to be identical, thus supporting their recent classification as synonyms. The results provide the basis for selecting specific combinations of restriction enzymes and gene regions of chloroplast DNA (cpDNA) to identify interspecific variation in the Zingiberaceae and to identify both highly conserved and variable regions. Overall, cpDNA depicted comparatively diverse genetic profile of the studied germplasm. The genetic information revealed here can be applied to the conservation and future breeding of Zingiber and Curcuma species.

DOI： 10.1111/j.1744-7348.2009.00322.x

Relationships of Zingiber species, and genetic variability assessment in ginger (Zingiber officinale) accessions from ex-situ genebank, on-farm and rural markets 査読

Shakeel Ahmad Jatoi, Akira Kikuchi, Makiko Mimura, San-San-Yi, Kazuo N. Watanabe

BREEDING SCIENCE 58 ( 3 ) 261 - 270 2008年9月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：JAPANESE SOC BREEDING

The Zingiber species comprises rhizomatous plants with special significance due to their multiple uses. Previously, we reported the additional use and suitability of primer pairs of rice microsatellite markers as RAPDs for diversity assessment in representative accessions of diverse taxa in the family Zingiberaceae. The current study aimed to investigate the genetic structure of Z. officinale at a genebank, small-scale subsistent farms and commercial markets, and the genetic relationships of three Zingiber species. A difference among accessions at the inter-specific level was observed and amplification of species-specific bands led to high polymorphism. Genetic variability in Z. officinale was exhibited by the three collection sources; however, some of the accessions from each source tended to cluster. AMOVA also displayed significant divergence among the three collection sources and explained most of the variance (87%) within the collection sources. In general, small-scale local farms displayed higher genetic variability in Z. offcinale compared to those from the genebank and markets. Comparative assessment displayed high allelic diversity in ginger from Myanmar as compared to other Asian countries. Genetic resources of Zingiber species, particularly available on farms, can be a useful source to capture and utilize diversity for conservation as well as further improvement in gingers.

DOI： 10.1270/jsbbs.58.261

Impact of Environmental Stress-Tolerant Transgenic Potato on Genotypic Diversity of Microbial Communities and Soil Enzyme Activities under Stress Conditions 査読

Makiko Mimura, Kipkorir E. Lelmen, Takayoshi Shimazako, Akira Kikucho, Kazuo N. Watanabe

MICROBES AND ENVIRONMENTS 23 ( 3 ) 221 - 228 2008年

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：JAPANESE SOC MICROBIAL ECOLOGY, DEPT BIORESOURCE SCIENCE

Transgenic crops able to tolerate environmental stress are being developed throughout the world. However, little data is available on the impact of environmental stress-tolerant transgenic crops on soil microorganisms and biochemistry. Recently developed transgenic potato plants carrying an environmental stress-related gene, DREB1A, with a stress-inducible promoter, are being evaluated for growth performance in greenhouses. In this study, we investigated microbial diversity and soil function to assess potential environmental risks of these transgenic potato lines, Genotypic diversity of the 16S-23S rRNA intergenic spacer region and activity levels of four enzymes were used as indicators of microbial genetic diversity and soil function, respectively. Salinity had a major effect on both bacterial (88-93%) and fungal (54-55%) diversity, while the transgene had a relatively small effect on genotypic structure (0-5%,) based on the analysis of variance. However, a few genotypes appeared only in soils planted with the transgenic lines. Some enzyme activities were found to differ significantly between the transgenic and non-transgenic lines, although the results were not repeatable in the second trial. These results suggest that abiotic growth environments had a stronger impact on soil microorganisms and biochemistry than did plant genotypes.

DOI： 10.1264/jsme2.23.221

Adaptive gradients and isolation-by-distance with postglacial migration in Picea sitchensis 査読

M. Mimura, S. N. Aitken

HEREDITY 99 ( 2 ) 224 - 232 2007年8月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：NATURE PUBLISHING GROUP

Fossil pollen records suggest rapid migration of tree species in response to Quaternary climate warming. Long-distance dispersal and high gene flow would facilitate rapid migration, but would initially homogenize variation among populations. However, contemporary clinal variation in adaptive traits along environmental gradients shown in many tree species suggests that local adaptation can occur during rapid migration over just a few generations in interglacial periods. In this study, we compared growth performance and pollen genetic structure among populations to investigate how populations of Sitka spruce (Picea sitchensis) have responded to local selection along the historical migration route. The results suggest strong adaptive divergence among populations (average Q(ST) 0.61), corresponding to climatic gradients. The population genetic structure, determined by microsatellite markers (R-ST = 0.09; F-ST = 0.11), was higher than previous estimates from less polymorphic genetic markers. The significant correlation between geographic and pollen haplotype genetic (R-ST) distances (r = 0.73, P < 0.01) indicates that the current genetic structure has been shaped by isolation-by-distance, and has developed in relatively few generations. This suggests relatively limited gene flow among populations on a recent timescale. Gene flow from neighboring populations may have provided genetic diversity to founder populations during rapid migration in the early stages of range expansion. Increased genetic diversity subsequently enhanced the efficiency of local selection, limiting gene flow primarily to among similar environments and facilitating the evolution of adaptive clinal variation along environmental gradients.

DOI： 10.1038/sj.hdy.6800987

Increased selfing and decreased effective pollen donor number in peripheral relative to central populations in Picea sitchensis (Pinaceae) 査読

Makiko Mimura, Sally N. Aitken

AMERICAN JOURNAL OF BOTANY 94 ( 6 ) 991 - 998 2007年6月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：BOTANICAL SOC AMER INC

Because mating system can be influenced by effective neighborhood size, density, and isolation, populations at range peripheries may differ from those in the center. The importance of peripheral populations to conservation and evolution is controversial, and additional information about their genetic structure and evolutionary dynamics will inform conservation strategies. In wind-pollinated species, selfing rate is generally negatively correlated with population size and density, and inbreeding may therefore increase toward range peripheries. Picea sitchensis has a long and narrow range along the Pacific Coast of North America that tapers toward the northern and southern peripheries. We investigated whether central and peripheral populations differ in mating system parameters. The results suggest that population position within the range has a strong effect on mating system, and geographic isolation appears to be associated with higher selfing. The estimated effective number of pollen donors was much higher in the center of the range (mean = 18.5) than at the periphery (mean = 3.6), while selfing rate increased from 7.3% in central populations to as high as 35.2% in the northern, isolated population. These strong geographical patterns suggest mating system is influenced by both population size and isolation at range peripheries.

DOI： 10.3732/ajb.94.6.991

SSR diversity of vegetable soybean [Glycine max (L.) merr.] 査読

Makiko Mimura, Clarice J. Coyne, Marie W. Bambuck, Thomas A. Lumpkin

GENETIC RESOURCES AND CROP EVOLUTION 54 ( 3 ) 497 - 508 2007年5月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：SPRINGER

Edamame [Glycine max (L.) Merr.] is a type of soybean selected for fresh or frozen vegetable use at an immature stage. Since edamame has a similar protein content, milder flavor, nuttier texture, and is easier to cook when compared to grain soybean, it is being promoted as a new vegetable for global consumption. Global production will require breeding programs for local adaptation; however, limited research has been published on genetic diversity of edamame varieties for the assessment of genetic resources. Simple sequence repeats (SSRs) were used to study the genetic diversity among 130 accessions, including edamame cultivars and landraces from Japan, China and the US, and also the new breeding lines in the US. Although it is assumed that elite edamame cultivars would have narrow genetic diversity, seventeen SSRs detected polymorphism to distinguish 99 of the 130 accessions. The cluster analysis generated nine clusters and 18 outliers. Genetic diversity within Japanese edamame was lower than that within Chinese vegetable soybean accessions (maodou), even though only 10 Chinese maodou were analyzed compared to 107 Japanese edamame. Cluster analysis revealed that the patterns of SSR diversity in edamame can generally distinguish maturity classes and testa color. We concluded that Japanese edamame have a narrow genetic base different from others and that SSRs can describe the patterns of genetic diversity among the elite vegetable soybean.

DOI： 10.1007/s10722-006-0006-4

RAPD variation in wild, weedy and cultivated azuki beans in Asia 査読

M Mimura, K Yasuda, H Yamaguchi

GENETIC RESOURCES AND CROP EVOLUTION 47 ( 6 ) 603 - 610 2000年12月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：KLUWER ACADEMIC PUBL

RAPD (Random Amplified Polymorphic DNA) variation was assessed in 42 accessions of azuki bean (Vigna angularis) including wild, weedy and cultivated races and in three accessions of two related species used as outgroups. A much lower level of genetic variation was observed in cultivated and weedy azuki beans compared to wild azuki bean. Wild azuki bean (V. angularis var. nipponensis) has relatively high genetic variation in subtropical highlands of Asia compared to the Far East. Although cultivated azuki bean has low RAPD variation, accessions from subtropical highlands and Southeast Asia showed different RAPD features compared to those of the Far East. It is hypothesized that the cultivated azuki bean has been derived from wild azuki bean in the Far East; the high variation in wild azuki bean has been created through its natural dissemination; and the relatively low variation in cultivated azuki bean has come about through human dissemination after genetic bottleneck reduced by domestication. In addition, high genetic diversity in wild azuki bean in subtropical highlands of Asia is regarded as an important genetic resource in azuki improvement.

DOI： 10.1023/A:1026584824584

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