Central Honshu Research Articles

Satellite Tracking of Migration Routes of the Eastern Buzzard (Buteo japonicus) in Japan through Sakhalin.

We satellite-tracked the eastern buzzard (Buteo japonicus) wintering in Japan to delineate both northward and southward migration routes, destinations, and stopover behavior. Twenty-two buzzards were captured and fitted with functional platform transmitter terminals. For these buzzards that departed from the capture sites, we observed a total of 65 northward migrations during 2008-2016 and a total of 55 southward migrations during 2008-2015. In spring, the eastern buzzards migrated eastward along the Seto Inland Sea in the Chugoku region or further inland. In eastern Honshu, they followed two different routes. One was to Hokkaido via the Tsugaru Peninsula from central or northern central Honshu northward along the side of the Sea of Japan in northern Honshu. The other was to Hokkaido via the Shimokita Peninsula, mainly from the Pacific Ocean side of northern Honshu, moving eastward through central Honshu. Of the 17 birds tracked, 10 summered in Sakhalin, three in Hokkaido, three in northern Honshu, and one unknown. In autumn, the buzzards retraced their northward migration routes. Of the 14 birds that were tracked the entire southward migration, 13 (92%) returned to their respective capture sites. One juvenile wintered in an area different from the capture site. Our study contributes to a deeper understanding of the distribution of breeding and wintering grounds and the migration routes of B. japonicus. In addition, the information on migration obtained in this study can contribute toward appropriate environmental impact assessment for wind power facilities in Japan.

Decades-long phylogeographic issues: complex historical processes and ecological factors on genetic structure of alpine plants in the Japanese Archipelago

Mountain regions are important places for biodiversity, where organisms could persist throughout prolonged periods and accumulate genetic divergence as well as promote speciation. Roles of mountains for biodiversity have been exclusively discussed in regions that have specifically diverse species or covered with ice-sheets during the Pleistocene glacial periods, whereas the importance of mountainous regions in East Asia has been less disputed. High mountains in the Japanese Archipelago, located at the eastern edge of the Eurasia continent, have one of southernmost populations of alpine and arctic-alpine plants that are also distributed in the northern Pacific and/or the circumarctic regions. Phylogeographic studies on the Japanese alpine plants have excluded their possible ephemeral occurrence during the current warm period, and rather, suggest persistence of alpine plants throughout several cycles of climate changes in the Pleistocene on high mountains in central Honshu, the main island of the Japanese Archipelago. In this review, I look through decade long phylogeographic studies and show complicated patterns of range dynamics of Japanese alpine plants. In addition, I note recent findings of genetic relationships of Japanese populations of alpine and/or arctic-alpine plants with those in northern regions and their possible ecological divergence in the Japanese Archipelago. Taken together, I provide several issues for understanding historical processes that established distribution of alpine plants following climate changes as well as their diversification and propose importance of Japanese populations of alpine plants on biodiversity in alpine communities across broader range, especially in the northern Pacific region.

Genetic variation of the relict maple Acer miyabei: uncovering its history of disjunct occurrence and the role of mountain refugia in shaping genetic diversity

Relict species provide valuable insights into the origin and formation of extant vegetation. Here, we aimed to elucidate the genetic structure and diversity of a riparian relic, Acer miyabei, in Japan. Once widely distributed, it now occurs in three isolated regions. The most northern regional group is located at low elevation on Hokkaido Island, whereas the southernmost group in central Honshu Island is at high elevation in a mountainous landscape. This contrastive distribution enables us to examine the effects of climate oscillations on genetic diversity in relation to topographic variation. We collected 604 individuals of A. miyabei from 43 sites. Their genetic structure and diversity were analyzed using 12 microsatellite markers and cpDNA sequences. According to structure analyses, ∆K was lowest at K = 2; the clustering essentially separated many of the individuals in the most northern regional group from the others. In contrast, the two southern groups were not clearly differentiated from each other, despite their geographic discontinuity. The proportion of private alleles was high in populations from the mountain terrain in the southern group although the number of extant populations is limited. Genetic clustering of A. miyabei is not perfectly congruent with the current patterns of geographic distribution. We infer that disjunction of the two southern groups occurred more recently than that between these groups and the northern group. The mountainous landscape in the most southern region likely provided multiple refugia and contributed to the retention of distinctive genetic variation.

Habitat selection of large herbivores evidenced as threats to alpine ecosystem

Across the globe, increasing populations of Cervidae have the potential to modify ecosystems. Long-term grazing pressure by deer not only alters vegetation but also affects ecosystem functions and interspecific interactions. It is recognized as a significant factor in ecological degradation. Alpine vegetation (i.e., alpine meadow) is an icon of alpine ecosystems and has thrived for centuries without the presence of large herbivores in Japan. However, in the alpine zone (>2700 m a.s.l.) of the South Alps National Park in central Honshu, Japan, sika deer (Cervus nippon) were first seen in the 1990s; thereafter, the vegetation noticeably changed starting in the 2000s. Nonetheless, virtually no information exists on habitat selection by these alpine sika deer. Here we analyzed (1) the altitudinal movement patterns of alpine sika deer, (2) the significant environmental factors affecting their habitat selection, and (3) estimated the relative probability of their habitat use via resource selection functions (RSF). The mean altitudinal difference between summer and winter home ranges was 1186 m, and the alpine sika deer arrived at the alpine ridgeline in June when the snow cover at >2400 m a.s.l. rapidly decreased. The mean altitude in the summer home range was 2635 ± 135 m. Alpine meadow, followed by Betula forests and tall grasslands, were preferred habitats by deer. The deer also preferred areas where snow melted in late spring and early summer. The deer's core habitat, indicated by higher RSF values (≥0.65), covered 45.2% of the study area, mostly distributed in the alpine zone. Our estimates clearly suggest the urgent need to prioritize specific areas for the conservation of the alpine vegetation in the South Alps National Park in Japan.

Modeling of cold-temperate tree Pinus koraiensis (Pinaceae) distribution in the Asia-Pacific region: Climate change impact

Pinus koraiensis Siebold & Zucc. (Korean pine) is a key species of the mixed cold temperate forests of Northeast Asia. Current climate change can significantly worsen the quality of P . koraiensis habitats and therefore lead to a large-scale structural and functional transformation of the East Asian mixed forests. We built a species distribution model (SDM) for P. koraiensis using the random forest classifier – a versatile machine learning algorithm, to discover overlap areas of potential species occurrence in the climate condition of the Last Glacial Maximum (∼21,000 year before present) and in the projected future climates (2070 year), from which possible permanent refugia for P . koraiensis were identified . Using the random forest supervised learning algorithm, we developed models of the modern distribution of P . koraiensis in accordance with the five selected bioclimatic variables (Kira’s warmth and coldness indices, the index of continentality, the rain precipitation index, and the snow precipitation index). In addition to current climatic conditions, we performed this analysis for the climate of the Last Glacial Maximum and for the future projected climate (2070) under scenarios RCP2.6 and RCP8.5. Among the predictors, the rain index appears to be the most significant. The land area estimates with high suitability for P . koraiensis was 303,785 ​km 2 under current climatic conditions, 586,499 ​km 2 for the Last Glacial Maximum, and 337,573 ​km 2 for the future (2070) period under the RCP2.6 scenario, and 397,764 ​km 2 under the RCP8.5 scenario. Most of the potential range of P . koraiensis during the Last Glacial Maximum was located outside the current distribution area of the species. The climatically suitable P . koraiensis habitats will likely disappear in the western part of its modern range. In the southern part of the range, which includes glacial refugia, the areas of continuous distribution of the P . koraiensis populations since the end of the Pleistocene are expected to be fragmented, but some localities in the north of the Korean Peninsula, northeast China, southern Primorye (Russia), and central Honshu (Japan) with suitable climatic conditions for the species will support the existence of populations.

Phylogeographic structure of an endemic lineage of the eight-barbel loach Lefua echigonia around the Suzuka and Yoro Mountains, central Honshu, Japan

Phylogeographic structure of an endemic lineage of the eight-barbel loach Lefua echigonia around the Suzuka and Yoro Mountains, central Honshu, Japan

Formation, Thermodynamic Structure, and Airflow of a Japan Sea Polar Airmass Convergence Zone

Abstract The Sea of Japan (SOJ) coast and adjoining orography of central Honshu, Japan, receive substantial snowfall each winter. A frequent contributor during cold-air outbreaks (CAOs) is the Japan Sea polar airmass convergence zone (JPCZ), which forms downstream of the highland areas of the Korean Peninsula (i.e., the Korean Highlands), extends southeastward to Honshu, and generates a mesoscale band of precipitation. Mesoscale polar vortices (MPVs) ranging in horizontal scale from tens (i.e., meso-β-scale cyclones) to several hundreds of kilometers (i.e., “polar lows”) are also common during CAOs and often interact with the JPCZ. Here we use satellite imagery and Weather Research and Forecasting Model simulations to examine the formation, thermodynamic structure, and airflow of a JPCZ that formed in the wake of an MPV during a CAO from 2 to 7 February 2018. The MPV and its associated warm seclusion and bent-back front developed in a locally warm, convergent, and convective environment over the SOJ near the base of the Korean Peninsula. The nascent JPCZ was structurally continuous with the bent-back front and lengthened as the MPV migrated southeastward. Trajectories illustrate how air–sea interactions and flow splitting around the Korean Highlands and channeling through low passes and valleys along the Asian coast affect the formation and thermodynamic structure of the JPCZ. Contrasts in airmass origin and thermodynamic modification over the SOJ affect the cross-JPCZ temperature gradient, which reverses in sign along the JPCZ from the Asian coast to Honshu. These results provide new insights into the thermodynamic structure of the JPCZ, which is an important contributor to hazardous weather over Japan.

Rinodina endospora и R. macrospora (Physciaceae, lichenized Ascomycota) — новые виды для Японии

Rinodina endospora and R. macrospora are reported as new to Japan. These species are known to be rare in Northeastern Asia and have a disjunctive distribution. Rinodina endospora was collected on bark of Alnus sp. and Salix sp. at 290 m a. s. l. in Hokkaido, and R. macrospora was on bark of Abies mariesii at elevation between 1960 and 2000 m a. s. l. in Toyama Prefecture of central Honshu. The paper provides data on morphology, ecology, differentiation and distribution of two Rinodina species.

The onset, dispersal and crop preferences of early agriculture in the Japanese archipelago as derived from seed impressions in pottery

This paper summarises the results of 225 studies of seed impressions in pottery assemblages from 182 archaeological sites across Kyushu, Shikoku and Honshu islands covering the Late/Final Jomon–Middle Yayoi period (ca. 2000–1 BCE). Focussing on rice, foxtail millet and broomcorn millet impressions, this archaeobotanical dataset was used to reconstruct when and where these crops arrived from the Eurasian mainland on these islands, how they dispersed and whether there were changes in crop preferences over time. While it is generally accepted that crop cultivation started during the Initial Yayoi period (ca. 800/700–500/400 BCE) in northern Kyushu, a limited number of seed impressions in Tottaimon phase 1 pottery suggests that rice and millet were present at different sites on Kyushu and in the Chugoku region even before this period. The earliest impression records also corroborate the hypothesis that rice arrived along with both millet crops, which for a long time have not been considered in research on early agriculture. The earliest crop records from eastern Japan (here Central Highlands to northern Honshu) come from early Fusenmon pottery, which was mainly used in the Central Highlands (central Honshu) and some adjacent areas, dating to the End of Final Jomon period (concurrent with the Initial Yayoi period in northern Kyushu). While the records from western Japan (here Kyushu to Kinki region) associated with Tottaimon pottery suggest mixed rice/millet cultivation during the Initial Yayoi and early part of the Early Yayoi (ca. 800/700–300 BCE) period, Fusenmon groups appear to have preferred millet. In western Japan, related to the spread of Ongagawa pottery, rice became the dominant crop during the late Early Yayoi period. This shift happened later (i.e., during the Middle Yayoi period; ca. 300–1 BCE) in eastern Japan. This ‘delay’ is manifested in impression records from the Tokai region representing a transitional area between eastern and western Japan. Rice-centred agriculture begun with the arrival of Ongagawa pottery on the Nobi Plain during the Early Yayoi period. In regions east of the plain settled by Jokonmon pottery groups a more rice-oriented agriculture is not evident before the Middle Yayoi period. An exceptional development is indicated for northern Tohoku (northernmost Honshu). Impression records from Sunazawa pottery suggest that local groups adopted only rice during the Early Yayoi period. The rice preference apparently continued into the Middle Yayoi period, but crop cultivation was abandoned by the beginning of the Late Yayoi period.

Seasonal Variation in Incidence of Stroke in a General Population of 1.4 Million Japanese: The Shiga Stroke Registry

Introduction: The purpose of this study was to investigate seasonal variation in stroke incidence using data from a large-scale stroke registry of general population in current Japan. Methods: Shiga Stroke Registry (SSR) is an ongoing population-based registry of stroke that occurred in the Shiga Prefecture in central Honshu, Japan. A total 6,688 cases of first-ever stroke, with onset dates ranging from 1 January 2011 to 31 December in 2013 were included in this study. Incidence rates of first-ever stroke in each season were estimated using the person-year approach and adjusted for age and sex using the Poisson regression models. Results: From 2011 to 2013, we identified a total of 6,688 stroke cases (3,570 men, 3,118 women), of which 4,480 cases had ischemic stroke (2,518 men, 1,962 women), 1,588 had intracerebral hemorrhage (857 men, 731 women) and 563 had subarachnoid hemorrhage (166 men, 397 women). Age- and sex-adjusted incidence rates of total stroke were 151 (95% confidence interval [CI] 144–160, p = <0.001 vs. summer) in spring, 130 (95% CI 122–137) in summer, 141 (95% CI 133–149, p = 0.020 vs. summer) in autumn and 170 (95% CI 161–179, p = <0.001 vs. summer) in winter. Seasonal variation was more pronounced in intracerebral hemorrhage than in ischemic stroke. Conclusion: In the present large-scale stroke registry of general population, incidence rates of stroke were highest in winter and lowest in summer in current Japan.

A new species of Orobdella (Hirudinida, Arhynchobdellida, Orobdellidae) from the Tsukuba Mountains in Japan

A small-type quadrannulate leech species, Orobdella montipumila sp. nov., from the Tsukuba Mountains in central Honshu island, Japan, is described. Phylogenetic analyses using nuclear 18S rRNA, 28S rRNA, histone H3, mitochondrial cytochrome c oxidase subunit I, tRNACys, tRNAMet, 12S rRNA, tRNAVal, 16S rRNA, tRNALeu and NADH dehydrogenase subunit 1 markers revealed that O. montipumila formed a monophyletic lineage with seven congeners that include the small-type quadrannulate O. masaakikuroiwai Nakano, 2014, which is endemic to montane regions of central Honshu. However, the present phylogenies showed that O. montipumila and O. masaakikuroiwai are not sister species, which confirms that reduction of body length has arisen independently in Orobdella leeches indigenous to central Honshu.

Bronze Age Globalisation and Eurasian Impacts on Later J\u014dmon Social Change

From northern China, millet agriculture spread to Korea and the Maritime Russian Far East by 3500–2700 BC. While the expansion of agricultural societies across the Sea of Japan did not occur until around 900 BC, the intervening period saw major transformations in the Japanese archipelago. The cultural florescence of Middle Jōmon central Honshu underwent a collapse and reorganisation into more decentralised settlements. Mobility increased as Late Jōmon influences spread from eastern into western Japan, and populations expanded to offshore islands such as Okinawa and the Kurils. In Kyushu and other parts of western Japan, the eastern Jōmon expansion was associated with the cultivation of adzuki and soybeans but, contrary to earlier assessments, there is no evidence for the introduction of cereal crops at this time. Here, we analyse archaeological and historical linguistic evidence of connections between the Eurasian mainland and the Japanese Islands c. 3500 to 900 BC. A re-evaluation of archaeological material discussed since the 1920s concludes that the transformations in Jōmon society during this period were at least in part a response to contacts with Eurasian Bronze Age cultures. Evidence for linguistic contact between Koreanic and the Ainuic languages which are presumed to have been spoken by Jōmon populations is also consistent with new Bronze Age mobilities. Although prehistoric Japan was one of the most isolated regions of Eurasia, we conclude that the historical evolution of societies in the Japanese archipelago after the third millennium BC was linked with processes of Bronze Age globalisation.

Associations between plasma testosterone levels and season, nutritional status, age, and body size in free-ranging male Asian black bears (Ursus thibetanus) in central Honshu, Japan

Testosterone is an important regulator of male reproduction in terms of spermatogenesis and physiological changes in the accessory reproductive organs. Despite the important role of the testosterone level in male reproduction, testosterone levels vary among male bears even during the breeding season, and the causative underlying factors remain unknown. We postulated that testosterone levels are higher during the breeding season than during other seasons in free-ranging male bears, and that testosterone levels increase with advancing age, larger body size, and better nutritional status. We assessed potential factors (season, time of sampling, body condition index, head circumference, and age) associated with the testosterone level in 80 blood samples collected from free-ranging Asian black bears (Ursus thibetanus) captured in barrel traps in the Ashio–Nikko Mountains and Okutama Mountains in central Honshu Island, Japan. The plasma testosterone level was higher during the breeding season (May–July) than during the non-breeding season (August–November). The body condition index was significantly and positively associated with the plasma testosterone level. None of the other factors were significantly associated with the plasma testosterone level. Therefore, the body condition index may be essential for maintaining high plasma testosterone levels. These findings imply that testosterone secretion might be activated in free-ranging males during the breeding season, and animals with good nutritional status may be able to maintain high plasma testosterone levels. This study uncovered an association between nutritional conditions and reproductive activity in male bears.

A new species of Cybaeus L. Koch, 1868 (Araneae, Cybaeidae) with simple genitalia from central Japan is the sister species of C. melanoparvus Kobayashi, 2006 with elongated genitalia

Spiders of the genus Cybaeus L. Koch, 1868 exhibit two major centers of diversity: Western North America and Japan. Several Japanese Cybaeus possess an elongated embolus in the male palp and elongated tubular spermathecae in the female genitalia. Here we describe Cybaeus koikeisp. nov. from central Honshu, Japan, which has an unelongated embolus and bulbous spermathecae. Phylogenetic analyses using nuclear and mitochondrial gene markers clearly support the monophyly of C. koikeisp. nov. and Cybaeus melanoparvus Kobayashi, 2006, a species with elongated genitalia. Both species share a similar habitus and a cluster of robust setae on the lateral surface of the male palpal patella. The latter is considered a synapomorphy for C. koikeisp. nov. and C. melanoparvus. A supplementary description of the spermathecae of C. melanoparvus is also provided.

本州中央山塊形成の力学像－浅・深プルームの交差湧昇－

本州中央山塊形成の力学像－浅・深プルームの交差湧昇－

Population differentiation in the leaf shape and growth form of Cardamine scutata Thunb. in tidal and non‐tidal habitats

AbstractRiparian habitats are associated with diverse hydrological conditions that may enhance population differentiation in species inhabiting areas close to water. Cardamine scutata Thunb. is a widespread riparian herb that is typically characterized by compound leaves. On the Nohbi Plain in central Honshu, Japan, it has, however, been reported that plants of C. scutata occurring in tidal wetlands along the lower reaches of large rivers have simpler leaves than those inhabiting areas further upstream. In this study, we quantitatively describe environmental conditions, leaf shape and other phenotypic traits of populations in tidal and non‐tidal habitats. Measurements of the electrical conductivity of interstitial water and fluctuations in water levels indicated that tidal populations of C. scutata occurred in typical tidal freshwater wetlands. We found that tidal and non‐tidal populations are characterized by distinct leaf shapes, simple and compound, respectively, under both field and common growth conditions. These observations indicate that differences in leaf shape reflect a genetic differentiation between populations of the same species inhabiting distinct habitats. In addition to leaf shape, we found several phenotypic differences relating to growth form, with plants in tidal populations having elongated hollowed stems and elongated inflorescences. We conclude that tidal populations of C. scutata are a discrete ecotype inhabiting freshwater tidal wetlands, presumably derived either through adaptation or genetic drift.

Late Quaternary tephrostratigraphy and cryptotephrostratigraphy of core MD012422: Improving marine tephrostratigraphy of the NW Pacific

We investigated the deep-sea sedimentary sequence of core MD012422 corresponding to the last 350 ka (since marine isotopic stage, MIS 10) from off Shikoku Island, NW Pacific Ocean, and refined its tephrostratigraphy. We detected many tephras and cryptotephras and correlated them with terrestrial tephras on the basis of the major- and trace-element compositions of their glass shards. Then we cross-checked our results against the reported marine tephrostratigraphy in the NW Pacific area and assessed the relative timing of tephra eruptions and bioevents. Many widespread tephras and cryptotephras originated from the Kyushu volcanic zone (Kuju, Aso, Kakuto, Aira, Ata, and Kikai volcanoes/calderas), along with the Takayama-Ng1 tephra (Tky-Ng1) from Suiendani volcano in central Honshu, were detected in the core. These tephras were used to validate and refine the reported NW Pacific marine tephrostratigraphy and to develop useful time-synchronous markers for this ocean area. Among the tephras, Ata-Torihama (Ata-Th) occurs at the MIS 7/8 transition (ca. 240 ka) and its horizon overlaps with a calcareous nannofossil biohorizon, the first appearance datum (FAD) of Emiliania huxleyi. Ata-Th and this biohorizon are stratigraphically above the Tky-Ng1 (MIS 8/9 transition, 290–300 ka) and Kakuto (Kkt, MIS 9/10 transition, 330–340 ka) tephras, and these tephras have the same stratigraphic relationship with this biohorizon in deep-sea sediments from the East China Sea, off Shikoku Island, and off central Honshu. However, in deep-sea cores from off northern Honshu, an inconsistency between the tephrostratigraphy and the FAD of E. huxleyi has been reported. This inconsistency can be explained by poor preservation of calcareous fossils in the deep waters off northern Honshu, which are more corrosive to calcium carbonate than the shallower waters off Shikoku Island. These findings emphasize the importance of cross-checking biohorizons against tephra horizons and of linking tephras between terrestrial and marine sequences to assess the synchronicity of globally correlated age indicators.

特集「本州中央部における第四紀隆起運動」の発刊にあたって

特集「本州中央部における第四紀隆起運動」の発刊にあたって

Refugia within refugium ofGeranium yesoense(Geraniaceae) in Japan were driven by recolonization into the southern interglacial refugium

AbstractRecent studies have found that geographical fragmentation and recurrent colonization result in complex genetic structures in refugial areas. This phenomenon, known as ‘refugia within refugium’, has been identified from many geographical locations. In Japan, the high-elevation mountains of central Honshu provided an interglacial refugium for alpine plants. Here we focused on the Geranium yesoense complex, which exhibits increased morphological variation in the refugial area, to determine whether this variation was shaped by recurrent colonization, range fragmentation or phenotypic changes independent of population history. We analysed single nucleotide polymorphism data and chloroplast genome sequences. Diversification in the G. yesoense species complex occurred in the mid-Pleistocene. The varieties are distinct entities and suggest the presence of a genetic cluster with highly disjunct distributions, occurring both in northern Japan and in southern refugial areas in central Honshu. Demographic analysis suggests that a single ancestral variety (var. nipponicum) evolved in the alpine region of central Honshu, and that subsequent migration from one of the two diverged northern varieties (var. pseudopratense) led to secondary contact with var. nipponicum during the last glacial period. Recolonization into refugial populations in central Honshu and hybridization between diverged populations have resulted in complex genetic structures among refugial populations.

A new species and distribution record of the ground beetle subgenus Falcinebria Ledoux & Roux, 2005 (Coleoptera: Carabidae: Nebria) from central Honshu, Japan

A new species and distribution record of the ground beetle subgenus Falcinebria Ledoux & Roux, 2005 (Coleoptera: Carabidae: Nebria) from central Honshu, Japan