Island Of Japan Research Articles

Early encounters

AbstractThis essay discusses two early encounters of theater that took place in different parts of the world at approximately the same time: in the German‐speaking countries in Europe and on the islands of Japan in Asia during the second half of the sixteenth century and the first decades of the seventeenth century. In both cases a particular kind of “national” theater emerged from these developments, which was able to embrace elements of highly diverse origins: Johann Wolfgang von Goethe’s Weimar theater plays and devices from different European performance cultures, and Izumo no Okuni’s kabuki elements stemming from a range of genres, including the Christian mystery plays. These new forms, recognized as a national theater, came into existence by way of intercultural performances. Ultimately, what came into being out of an “intercultural” encounter was later deemed genuinely “intracultural.”

Tree hazards compounded by successive climate extremes after masting in a small endemic tree, Distylium lepidotum, on subtropical islands in Japan.

Ongoing global warming increases the frequency and severity of tropical typhoons and prolonged drought, leading to forest degradation. Simultaneous and/or successive masting events and climatic extremes may thus occur frequently in the near future. If these climatic extremes occur immediately after mass seed reproduction, their effects on individual trees are expected to be very severe because mass reproduction decreases carbohydrate reserves. While the effects of either a single climate extreme or masting alone on tree resilience/growth have received past research attention, understanding the cumulative effects of such multiple events remains challenging and is crucial for predicting future forest changes. Here, we report tree hazards compound by two successive climate extremes, a tropical typhoon and prolonged drought, after mass reproduction in an endemic tree species (Distylium lepidotum Nakai) on oceanic islands. Across individual trees, the starch stored within the sapwood of branchlets significantly decreased with reproductive efforts (fruit mass/shoot mass ratio). Typhoon damage significantly decreased not only the total leaf area of apical shoots but also the maximum photosynthetic rates. During the 5‐month period after the typhoon, the mortality of large branchlets (8–10‐mm diameter) increased with decreasing stored starch when the typhoon hit. During the prolonged summer drought in the next year, the recovery of total leaf area, stored starch, and hydraulic conductivity was negatively correlated with the stored starch at the typhoon. These data indicate that the level of stored starch within branchlets is the driving factor determining tree regrowth or dieback, and the restoration of carbohydrates after mass reproduction is synergistically delayed by such climate extremes. Stored carbohydrates are the major cumulative factor affecting individual tree resilience, resulting in their historical effects. Because of highly variable carbohydrate levels among individual trees, the resultant impacts of such successive events on forest dieback will be fundamentally different among trees.

Distribution, Temporal Change, and Conservation Status of Tropical Seagrass Beds in Southeast Asia: 2000–2020

Although Southeast Asia is a hotspot of global seagrass diversity, there are considerable information gaps in the distribution of seagrass beds. Broad-scale seagrass distribution has not been updated in the global seagrass database by UNEP-WCMC since 2000, although studies on seagrasses have been undertaken intensively in each region. Here we analyze the recent distribution of tropical seagrass beds, their temporal changes, causes of decline and conservation status in Southeast Asia (plus southern mainland China, Taiwan and Ryukyu Island of Japan) using data collected after 2000. Based on the 195 literature published since 2000, we identified 1,259 point data and 1,461 polygon data showing the distribution of seagrass beds. A large discrepancy was found in the seagrass bed distribution between our updated data and the UNEP-WCMC database, mostly due to inaccurate and low resolution location information in the latter. Temporal changes in seagrass bed area analyzed for 68 sites in nine countries/regions demonstrated that more than 60% of seagrass beds declined at an average rate of 10.9% year–1, whereas 20% of beds increased at an average rate of 8.1% year–1, leading to an overall average decline of 4.7% year–1. Various types of human-induced threats were reported as causes for the decline, including coastal development, fisheries/aquaculture, and natural factors such as typhoons and tsunamis. The percentage of seagrass beds covered with existing marine protected areas (MPAs) varied greatly among countries/regions, from less than 1% in Brunei Darussalam and Singapore to 100% in southern Japan. However, the degree of conservation regulation was not sufficient even in regions with higher MPA coverage. The percentage of seagrass beds within EBSAs (Ecologically and Biologically Significant Area determined by the Convention of Biological Diversity) was higher than that within MPAs because EBSAs cover a greater area than MPAs. Therefore, designating EBSAs as legally effective MPAs can greatly improve the conservation status of seagrass beds in Southeast Asia.

Shifting roles of the East China Sea in the phylogeography of red nanmu in East Asia

AbstractAimThe effect of eustasy driven by climatic oscillations on species diversification across the East China Sea (ECS) remains unclear. In this study, Machilus thunbergii (红楠, red nanmu in Chinese) was used as a model species to determine whether the ECS acted as either a “species pump” or “species vacuum” during the Pleistocene.LocationsEastern China, and southern and central Japan.TaxonLauraceae.MethodsEcological niche modelling was employed to predict the potential distribution of M. thunbergii during the Last Glacial Maximum (LGM) and the last interglacial period. Nuclear microsatellite and chloroplast markers were used to reveal the phylogeographic pattern and infer the population history of 33 M. thunbergii populations.ResultsThe ecological niche models suggested that the ECS provided potentially suitable habitats for M. thunbergii during the LGM. A sharp change in cpDNA haplotypes was found along the eastern China coasts, while microsatellites revealed a clinal pattern for genetic composition from eastern China to central Japan. The divergent lineages formed an admixture on the Zhoushan Archipelago of China and Kyushu Island of Japan. The estimated divergent and admixture times were c. 68 kyr and c. 15 kyr, corresponding to the periods where there were rising sea levels after the MIS4 glaciation and falling sea levels during the LGM, respectively.Main conclusionsMachilus thunbergii probably underwent alternating population isolation during interglacial periods and connection during glacial maxima across the ECS, but such periodicity of isolation and connection seems not to have promoted diversification as suggested by the species pump hypothesis. Incipient divergence has been periodically wiped out due to frequent coalescence, rendering the ECS more like a “species vacuum”, particularly for species with relatively long generation lengths.

Integrating Remote Sensing and a Markov-FLUS Model to Simulate Future Land Use Changes in Hokkaido, Japan

As the second largest island in Japan, Hokkaido provides precious land resources for the Japanese people. Meanwhile, as the food base of Japan, the gradual decrease of the agricultural population and more intensive agricultural practices on Hokkaido have led its arable land use to change year by year, which has also caused changes to the whole land use pattern of the entire island of Hokkaido. To realize the sustainable use of land resources in Hokkaido, past and future changes in land use patterns must be investigated, and target-based land use planning suggestions should be given on this basis. This study uses remote sensing and GIS technology to analyze the temporal and spatial changes of land use in Hokkaido during the past two decades. The types of land use include cultivated land, forest, waterbody, construction, grassland, and others, by using the satellite images of the Landsat images in 2000, 2010, and 2019 to achieve this goal to make classification. In addition, this study used the coupled Markov-FLUS model to simulate and analyze the land use changes in three different scenarios in Hokkaido in the next 20 years. Scenario-based situational analysis shows that the cultivated land in Hokkaido will drop by about 25% in 2040 under the natural development scenario (ND), while the cultivated land area in Hokkaido will remain basically unchanged in cultivated land protection scenario (CP). In forest protection scenario (FP), the area of forest in Hokkaido will increase by 1580.8 km2. It is believed that the findings reveal that the forest land in Hokkaido has been well protected in the past and will be protected well in the next 20 years. However, in land use planning for future, Hokkaido government and enterprises should pay more attention to the protection of cultivated land.

Phylogeography of the stoneflyKamimuria tibialis: multiple glacial refugia and sympatric occurrence of different lineages in the southern islands of Japan

AbstractTo elucidate the effect of Pleistocene climatic fluctuations on the historical distribution and geographical genetic structure of temperate Japanese species, we performed phylogeographical and demographic analyses using mitochondrial gene sequences obtained from the stonefly species Kamimuria tibialis, sampled from four main islands of the Japanese Archipelago (i.e. Hokkaido, Honshu, Shikoku and Kyushu) and Tsushima Island. We detected three main clades with distinct geographical distributions, including the Tsushima, Kyushu and Hokkaido–Honshu–Shikoku phylogroups. These groups were estimated to have diverged from one another 0.54–2.02 Mya, suggesting they have undergone several glacial cycles in different refugia. Our results showed that during the glacial epochs and with a fall in sea-level, gene flow was limited among Tsushima and Kyushu, and among Hokkaido and Honshu, probably because the straits between these islands are deep. The population in Kyushu and Shikoku, the southernmost islands, exhibited high genetic diversity, with two distinct haplotype lineages occurring sympatrically. These results suggest that the population division into multiple refugia and the existence of stable southern refugia have contributed to the high genetic diversity of the species in this region.

일본 육군성 참모국 출신 나카네 기요시(中根淑)의 일본지리교과서 편찬과 독도 인식

Nakane Kiyoshi(中根淑) worked for the Japanese Ministry of Army and wrote the Heiyo- Nakane Kiyoshi(兵要日本地理小誌) etc.. His geographical textbooks has long been used as a Japanese geography textbook as well as a military textbook. The Army Staff Bureau's perception of Japanese territory is well reflected in the Heiyo- Nakane Kiyoshi, which was compiled based on the latest information at the time. Japan's islands located on the stage were introduced in the body of Heiyo- Nakane Kiyoshi and Japanese territory was displayed Nihonkoku-zenzu(日本國全圖) and Sanindo-no-zu(山陰道之圖), but Ulleungdo and Dokdo was not marked. As a result, Nakane did not recognise Ulleungdo and Dokdo as Japanese territory. The situation of changes of Japanese territory was accurately reflected in Dokugaku-Niho nchiri-sho(獨學日本地理書), Ulleungdo and Dokdo was not recognized as Japan ese territory. Nakane clearly wrote that Dokdo(Matsushima), Ulleungdo(Takeshima) beca me Korean territory in Nakane Kiyoshi(日本地理小誌). This is the first and only case in Japanese geography textbooks, and is also evident in Nihonkoku-zenzu and Sanindo-no-zu. Nakane's perception that Dokdo(Matsushima), Ulleungdo(Tak eshima) belongs to Joseon continues in Nihon-sozu(日本總圖) and Sanindo-no-zu of Nihonchiri-shogaku(日本地理小學).

Distribution and Genetic Diversity of the Amphibian Chytrid in Japan.

While research on frog chytrid fungus Batrachochytrium dendrobatidis (Bd), an infectious disease that threatens amphibian diversity, continues to advance worldwide, little progress has been made in Japan since around 2010. The reason for this is, which we pointed out in 2009, that the origin of frog chytrid fungus may be in the East Asian region, including Japan based on the Bd ITS-DNA variation, and as few cases of mass mortality caused by this fungus have been observed in wild amphibian populations in Japan, the interest of the Japanese government and the general public in Bd has waned. However, we believe that organizing the data obtained so far in Japan and distributing the status of frog chytrid fungus in Japan to the world will provide useful insight for future risk management of this pathogen. We collected more than 5500 swab samples from wild amphibians throughout Japan from 2009 to 2010. Then, we investigated the infection status using the Nested-PCR method. We sequenced the obtained DNA samples and constructed a maximum-parsimony (MP) tree to clarify the phylogenetic diversity of Bd. We detected Bd infection in 11 (nine native and two alien) amphibian species in Japan and obtained 44 haplotypes of Bd ITS-DNA. The MP tree showed a high diversity of Bd strains in Japan, suggesting that some strains belong to Bd-GPL and Bd-Brazil. Except for local populations of the Japanese giant salamanders Andrias japonicus in Honshu Island and the sword tail newts Cynops ensicauda in Okinawa Island, the Bd infection prevalence in native amphibian species was very low. The alien bullfrog Aquarana catesbeiana had high Bd infection rates in all areas where they were sampled. No Bd infection was detected in other native amphibians in the areas where giant salamanders, sword tail newts, and bullfrogs were collected, suggesting that many native amphibians are resistant to Bd infection. The sword tail newt of Okinawa Island had both the highest infectious incidence and greatest number of haplotypes. The giant salamanders also showed relatively high infection prevalence, but the infected strains were limited to those specific to this species. These two Caudata species are endemic to a limited area of Japan, and it was thought that they may have been refugia for Bd, which had been distributed in Japan Islands for a long time.

Genome-Wide SNP Data Revealed Notable Spatial Genetic Structure in the Deep-Sea Precious Coral Corallium japonicum

Estimating the spatial extent of gamete and larval dispersal of deep-sea coral species, is challenging yet important for their conservation. Spatial autocorrelation analysis is useful for estimating the spatial range of dispersal of corals; however, it has not been performed for deep-sea coral species using genome-wide single nucleotide polymorphisms (SNPs). In this study, we examined the spatial genetic structure of a deep-sea coral species—the Japanese red coral, Corallium japonicum, sampled off the coast of Kochi, which lies to the southwest of the Shikoku Island in Japan; the Kochi region suffers from over-harvesting because of its high commercial value. We also examined the power of detecting significant spatial genetic structure by changing the number of loci and the proportion of missing data using both de novo analysis and mapping analysis. Similar results were obtained for both de novo and mapping analysis, although a higher number of loci were obtained by the mapping method. In addition, “many SNPs with a lot of missing data” was generally more useful than “a small number of SNPs with a small amount of missing data” to detect significant fine-scale spatial genetic structure. Our data suggested that more than 700 neutral SNPs were needed to detect significant fine-scale spatial genetic structure. The maximum first distance class that can detect significant spatial genetic structure within Kochi for the C. japonicum population was less than 11 km, suggesting that the over-harvesting of C. japonicum within a diameter of approximately 11 km in the Kochi area should be avoided, because this can cause the local extinction of this species.

\u201cWisdom of the Elders\u201d or \u201cLoss of Experience\u201d as a Mechanism to Explain the Decline in Traditional Ecological Knowledge: A Case Study on Awaji Island, Japan

Previous studies have reported that older people are more knowledgeable about nature than the younger generation. The relationship between people’s age and level of knowledge can be explained via two mechanisms: knowledge increases with age (wisdom of the elders), and opportunities to acquire knowledge decrease with successive generations (loss of experience). In this study, we examined the association between age and knowledge regarding the use of wild fruits among people living on Awaji Island in Japan. Analysis of the results revealed that the decline in knowledge among young people can be attributed to loss of experience. Furthermore, we found that the channels of knowledge transfer have changed between generations, earlier, children received it from their peers, but in recent years, it has been coming to them from older people and teachers.

Climatological Features of Strong Winds Caused by Extratropical Cyclones around Japan

AbstractWe examined the climatological features of strong winds associated with extratropical cyclones around Japan during 40 seasons between November and April from 1979/80 to 2018/19 using reanalysis data. Our assessments revealed that the extratropical cyclones caused most of the strong winds around Japan (80%–90%). Notably, the contribution of explosively developing extratropical cyclones is larger (70%–80%). The strong winds are mainly related to the warm conveyor belt (WCB) and cold conveyor belt (CCB) inside the explosive cyclones. Moreover, the strong winds tend to be distributed widely over the southwestern quadrant of the cyclones. This is due to the intensification of the horizontal pressure gradient between the mature cyclones and the Siberian high extending from the Eurasian continent to Japan. We investigated the regionality of strong winds by highlighting the three areas with high frequencies of strong winds: the area around Hokkaido (i.e., the northernmost island of Japan; area A), and the areas around the Japan Sea side (area B) and the Pacific Ocean side (area C) of the main island of Japan. The features of the seasonal change in the frequency of the strong winds differ in each area, which reflects the seasonal change in the activities of the explosive cyclones. Moreover, the CCB, the head of the CCB and WCB, and the CCB and WCB bring the strong winds to areas A, B, and C, respectively. The timing of the appearance of these windstorms during the life cycles of typical cases highlighted in this study is consistent with that observed in Europe.

A Taxonomic study of two species of Thiotricha Meyrick (Lepidoptera: Gelechiidae), from southwestern Japan, with notes on the biology of their immature stages.

The taxonomy and biology of the immature stages of two gelechiid species of Thiotricha Meyrick, 1886, found in the southeastern part of the Sino-Japanese region is presented. Thiotricha lumnitzeriella Kyaw, Ueda Hirowatari sp. nov., from islands in southwestern Japan is described. The larva of this species feeds as a portable case maker on Lumnitzera racemosa Willd. (Combretaceae). Thiotricha gemmulans Meyrick, 1931 originally described from India is newly recorded from Japan, mainland China, and Thailand. This species feeds as a portable case maker on Glochidion zeylanicum var. lanceolatum (Hayata) and G. zeylanicum var. zeylanicum (Gaertn.) A. Juss (Phyllanthaceae). Thiotricha acrophantis Meyrick, 1936 is newly synonymized with T. gemmulans. Images of the adults of Thiotricha lumnitzeriella sp. nov. and T. gemmulans including genitalia, and images and illustrations of the larval chaetotaxy and pupa for both species are provided. Larval feeding habits are described in detail.

Oscillatory characteristics of young mangroves exposed to short-period waves

Ultragravity waves with a period of <1 s are often ignored in coastal engineering because they have little effect on coastal structures. In this study, we demonstrate that even though the height of short-period waves is small, the waves cause young mangroves to oscillate greatly. Indoor and onsite mangrove growth tests, oscillation tests, wave experiments, and theoretical analyses were conducted on a mangrove species (Kandelia obovata) to determine the oscillatory characteristics of young mangroves when exposed to small waves. Natural period of oscillation of the young mangrove shoots was less than 0.5 s. Their resonance occurred when the wave period was a multiple of the natural period of oscillation of the mangrove shoots. Because of resonance, the horizontal acceleration of the mangrove leaves was calculated to reach twice the acceleration of gravity. If these waves act for a long time, young leaves can fall. A test performed on a mangrove forest in Amami Island in Japan revealed that although the mangrove heights grew rapidly, their stem thickness did not change substantially. Thus, the young mangroves need to gain rigidity in a short period to withstand short-period waves. To increase the survival rate of the young mangroves, short-period waves, whose period is close to the natural period of oscillation of the mangrove stems, could be avoided by installing a small breakwater. However, stem oscillations may positively affect leaf photosynthesis because small waves have the same effect as a gentle breeze and can promote the growth of young mangroves. Therefore, further studies on ultragravity waves and the growth of young mangroves are required.

Arc volcanic suite from a Miocene subduction system in SW Japan: A geochemical and zircon U-Pb-Lu-Hf study

Arc volcanic rocks are important products of the subduction factory in convergent plate margins and contribute significantly to crust building in the evolving Earth. Southwest Japan provides a window to gain insights into the ongoing subduction-related processes and the early stages of crust building. In this study, we investigate a suite of volcanic rocks from the central segment of the Setouchi volcanic belt (SVB) including dacites and andesite from northeast Shikoku island in southwestern Japan based on petrologic, geochemical, zircon U--Pb, REE (rare-earth element), and Lu--Hf analyses. The dacites and andesite from this region are peraluminous, medium-K, and calc-alkalic, with LREEs (light rare-earth elements) enrichment and depleted in HREEs (heavy rare-earth elements) and HFSEs (high field-strength elements). Two groups of zircon grains occur in these volcanic rocks as revealed from U--Pb studies. The older magmatic zircon grains are of late Cretaceous age and show typical oscillatory zoning yielding 206Pb/238U age peaks at 83.6 Ma with dominantly negative εHf(t) values (−3.7 to +0.9), indicating older reworked crustal sources. The second group is represented by thin elongated prismatic grains with banded structure, which yield 206Pb/238U age peaks at 13.8 Ma and displaying more positive εHf(t) values (+2.4 to +7.7), indicating juvenile sources. A compilation and comparison of the available geochemical and geochronological data on the volcanic suites in the SVB reveal a common source for the coeval island-arc volcanic rocks (andesite-dacites-rhyolite) and HMA (high magnesium andesites). Compared with the HMA, the other volcanics are more evolved through crustal contamination and fractionation.

Elucidation of the history of coastal utilization of the Setouchi islands, Japan by multifaceted analysis and three-dimensional geological modelling

Three of the four main islands in Japan are separated by the Seto Inland Sea in the country's Setouchi region. This area is an important inland sea of Japan and is interesting for researchers in various fields because of its historically active exchange and trade. Associate Professor Keisuke Makibayashi, Research Center for Asian Archaeology of Industry and Culture, Ehime University, Japan, is involved in a project focused on the Miyan'na site, which is a salt-making site from the Kofun period and the Kamakura period on a small island in the Seto Inland Sea in Ehime Prefecture that is seeking to restore the lost landscape. This work involves the use of different research methods such as particle size analysis, soil physics and chemistry analysis, as well as organising a cross-sectional view of the Miyan'na site, performing 3D geological modelling, using scientific data to explain beach ridges and understand historical human activities, and performing excavations. Ultimately, the researchers want to return the landscape to the local community, thereby contributing to the people in the area. The research is also expected to make important contributions to archaeology, history and environmental science.

DNA-based diversity assessment reveals a new coral barnacle, Cantellius alveoporae sp. nov. (Balanomorpha: Pyrgomatidae) exclusively associated with the high latitude coral Alveopora japonica in the waters of southern Korea.

In the present study, the Indo-Pacific coral associated barnacle Cantellius euspinulosum (Broch, 1931) was found to have cryptic species in Korea, Taiwan and other regions based on molecular studies. However, the original specimens of C. euspinulosum from Broch have not been previously described or illustrated, making it difficult to assign which cryptic species to the original C. euspinulosum. The original specimen of C. euspinulosum was examined and illustrated here, and the species identity of C. cf. euspinulosum collected from Jejudo Island in the present study and other cryptic species (based on literature illustrations) in the Indo-Pacific were evaluated.C. euspinulosum from Singapore, Java, Mergui Archipelago in Andaman Sea and Nha Trang represented the C. euspinulosum identified by Broch (1931). It is a generalist on Acropora, Favia, Favites, Leptoria, Montipora, Pachyseris and Pocillipora corals and distributed in the Indo-Pacific region. Morphological examination and DNA sequencing (COI, 12S DNA sequences) in the present study showed that C. cf. euspinulosum from Jejudo Island, Korea represents a distinct species, herein named C. alveoporae sp. nov. Cantellius alveroporae sp. nov. is a specialist species that only grows on Alveopora and also present in Palau, and Ogasawara Island in Japan. Cantellius cf. euspinuloum in Taiwan, the Moscos Island, and Australia belong to several other distinct species awaiting further morphological and molecular studies. At least five cryptic species of C. euspinulosum were identified in the present study, including both specialist and generalists.

Frictional stability of porous tuff breccia under subsurface pressure conditions and implications for shallow seismicity

Thick sediment layers frequently cover the Japan islands’ surface, and their frictional properties significantly affect the shallow slip behavior that occurs during earthquakes. However, laboratory data on the properties of the shallow zone remain limited. We collected tuff breccia samples from deep borehole cores in the Miocene “Green Tuff” formation, a major surface cover, and performed velocity-stepping friction tests on these samples under in situ stresses of 2 to 20 MPa to assess the velocity dependence of their frictional strength. The samples exhibit predominantly frictionally stable, velocity-strengthening behavior over the range of normal stresses tested, which supports the hypothesis that shallow sediment layers are seismically quiescent. This result is consistent with the low seismicity and attenuation of coseismic slip occurring in the shallow zone that is observed during regional earthquakes. Microstructural observations of the postmortem samples using optical and scanning electron microscopes indicate a fabric transition from boundary shear localization to distributed cataclastic flow with increasing normal stress. Our laboratory investigation of the depth-variable distribution of the frictional velocity dependence of a shallow sediment layer would provide further insight into the mechanical role for earthquake rupture dynamics and shallow seismicity.

Structure and movement of the hybrid zone between two divergent lineages of the Japanese newtCynops pyrrhogaster(Amphibia: Urodela) in central Japan

The maintenance mechanisms of hybrid zones between two lineages/species and their gene flow dynamics are major topics for speciation studies. Elucidating these dynamics can help us to understand the process of speciation. The newt Cynops pyrrhogaster is distributed on the main islands of Japan and comprises five mitochondrial DNA (mtDNA) lineages. In this study, we surveyed the genetic relationship between two lineages (northern and central) around their boundary. We genotyped 202 individuals from 24 populations using the mitochondrial cytochrome b gene and 12 microsatellite loci. MtDNA analysis revealed that the two lineages were distributed parapatrically to each other without coexistence, whereas the microsatellite analysis indicated the presence of a hybrid zone. The estimated dispersal rates were higher from both parental lineages to the hybrid populations than those in the opposite directions. These data indicate that the hybrid zone is a tension zone, which is maintained by an equilibrium between selection against hybrid individuals and the invasion of both parental individuals from adjacent areas. The two parental lineages are genetically moderately isolated from each other and appear to be biologically independent species. The overall dispersal rate was more pronounced in the south-to-north direction. More than 10 individuals having central type of mtDNA retained some genetic characteristics derived from the northern lineage, which can be regarded as genetic footprint of their northern lineage ancestor. These results suggest that the hybrid zone has shifted from south to north, resulting in replacing the range of the northern lineage to that of the central lineage.

Conservation genetics of critically endangered Crepidiastrum grandicollum (Asteraceae) and two closely related woody species of the Bonin Islands, Japan

Crepidiastrum grandicollum is a critically endangered insular endemic herb found only on two oceanic islands of the Bonin Islands in Japan, namely Chichijima Island and Anijima Island. It is explicitly threatened by herbivory pressure from introduced animals. In 2009, a conservation program for C. grandicollum was begun to ensure its future persistence. To provide further information for conservation planning, we investigated the genetic diversity of C. grandicollum using 13 novel microsatellite markers in 55 individuals from four wild populations and an ex situ living collection. Two closely related woody species were also included for interspecific comparison: seven individuals of Crepidiastrum ameristophyllum and 13 of Crepidiastrum linguifolium. The 13 markers were applicable to all three species and identified 129 alleles in total. We found a clear genetic differentiation between C. grandicollum from Anijima Island and Chichijima Island. Crepidiastrum grandicollum also had low expected heterozygosity and allelic richness in populations compared to the two closely related species. Reconstructed divergence history suggested that differentiation between the islands had occurred several thousand generations ago. We suggest separate conservation units for C. grandicollum on Anijima Island and Chichijima Island given the clear (and putatively historical) genetic differentiation, which may result in speciation in the future.

A Surprisingly Non-attractiveness of Commercial Poison Baits to Newly Established Population of White-Footed Ant, Technomyrmex brunneus (Hymenoptera: Formicidae), in a Remote Island of Japan

The white-footed ant, Technomyrmex brunneus, was newly introduced and established in a remote island of Japan and has caused unacceptable damage to the daily life of residents. To establish proper control measures, the present study investigated whether T. brunneus is effectively attracted to commercially available poison baits used to exterminate common household pest ants and the Argentine ant in Japan. Cafeteria experiments using three types of nontoxic baits and eight types of commercial poison baits for ants were conducted in the field, and the attractiveness was compared among the baits. The liquid poison bait “Arimetsu,” which consists of 42.6% water, 55.4% sugar, and 2.0% borate, and nontoxic 10% (w/v) sucrose water showed the highest attractiveness. On the other hand, other commercial poison baits were not as attractive. Therefore, sucrose liquid is the most effective attractive component to use in poison baits for T. brunneus.