Yakushima Island Research Articles

Trophically polymorphic loggerhead sea turtles show similar interannual variability in clutch frequencies: implications for estimating population size of iteroparous animals

AbstractWe investigated how trophic polymorphism observed at a loggerhead sea turtle (Caretta caretta) rookery affected the interannual variability of clutch frequency (the number of clutches laid by a female during a nesting season) and of the number of total located nests, based on comprehensive nighttime and daytime field surveys conducted at Yakushima Island, Japan, over a non‐consecutive eight‐year period. Taking into account the fact that lower trophic‐level sea turtles show greater variability in these parameters, we anticipated clutch frequency and the number of total located nests to vary more in low trophic‐level oceanic planktivores (secondary consumers) than in high trophic‐level neritic benthivores (tertiary consumers). Oceanic planktivores and neritic benthivores were classified by stable isotope ratios in egg yolks. Neritic foragers had higher clutch frequencies than oceanic foragers in any year. Contrary to our anticipation, however, both types of foragers showed similarly low interannual variability in clutch frequencies. No significant correlations were found between mean clutch frequencies and the estimated number of nests made by either oceanic or neritic foragers and the number of total located nests. Interannual fluctuations in the total number of nests made by loggerhead turtles, whether trophically monomorphic or polymorphic, seem to be driven more by the number of females than by clutch frequency; this suggests that the number of total located nests can be a good proxy for the population size of iteroparous animals at relatively high trophic levels.

Effects of volcanic parent materials on the acid buffering capacity of forest soils on Yakushima Island, Japan

ABSTRACT Soil acidification is a natural pedogenetic process in forest ecosystems, but is accelerated by acidic deposition. Soils on Yakushima Island, in southwestern Japan, are derived from granitic bedrock and volcanic parent materials influenced by eolian dust inputs. Acid deposition and low acid-neutralizing capacity (ANC) of granite-derived soils are hypothesized to be the cause of acidic stream water that has been widely observed on Yakushima. It remains unclear, however, whether ANCs are also limited in volcanic soils, which contain weatherable minerals and have high buffering capacities. To compare acidification rates between granite-derived soils and volcanic soils, we estimated changes in ANCs between granite and volcanic parent materials and the resulting soils at a pedogenetic timescale, using the mass balance of titanium. After 7300 years of soil development following the eruption of the Kikai caldera, decreased ANCs and total base reserves were observed in both granite-derived and volcanic soils, compared to their respective parent materials. No difference in soil ANC was observed between granite and volcanic parent materials. Different cations contribute to acid neutralization in soils: decreasing ANC results primarily from the loss of Al in granite-derived soils, while acidity is neutralized by the loss of base cations from volcanic soils. In granite-derived soils, resistance to weathering and K retention in 2:1 type silicate clays limit the loss of bases while increasing the accumulation of exchangeable Al. In volcanic soil profiles, base leaching and the sorption of organic acids onto short-range order minerals can neutralize acidity, although erosion and admixing of granite or eolian dust-derived materials lead to a reduction of ANC in surface soil horizons.

Ambiguous species boundaries: Hybridization and morphological variation in two closely related Rubus species along altitudinal gradients.

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.

Genetic consequences of being a dwarf: do evolutionary changes in life-history traits influence gene flow patterns in populations of the world's smallest goldenrod?

Contrasting life-history traits can evolve through generations of dwarf plant ecotypes, yet such phenotypic changes often involve decreased plant size and reproductive allocation, which can configure seed dispersal patterns and, subsequently, population demography. Therefore, evolutionary transitions to dwarfism can represent good study systems to test the roles of life-history traits in population demography by comparing genetic structure between related but phenotypically divergent ecotypes. In this study, we examined an ecotypic taxon pair of the world's smallest goldenrod (stem height 2.6 cm) in alpine habitats and its closely related lowland taxon (30-40 cm) found on Yakushima Island, Japan. Genetic variation in chloroplast DNA sequences, nuclear microsatellites and genome-wide single-nucleotide polymorphisms were used to investigate 197 samples from 16 populations, to infer the population genetic demography and compare local genetic structure of the ecotypes. We found a pronounced level of genetic differentiation among alpine dwarf populations, which were much less geographically isolated than their lowland counterparts. In particular, several neighbouring dwarf populations (located ~500 m apart) harboured completely different sets of chloroplast haplotypes and nuclear genetic clusters. Demographic modelling revealed that the dwarf populations have not exchanged genes at significant levels after population divergence. These lines of evidence suggest that substantial effects of genetic drift have operated on these dwarf populations. The low-growing stature and reduced fecundity (only 3.1 heads per plant) of the dwarf plants may have reduced gene flow and rare long-distance seed dispersal among habitat patches, although the effects of life-history traits require further evaluation using ecological approaches.

Nitrogen mineralization rates of the soils incubated under different temperatures from different elevations along an environmental gradient on Yakushima Island

AbstractSoil nitrogen (N) mineralization is the product of the soil biochemical properties and temperature. It is known that in situ soil N mineralization monotonously decreases with increasing elevation along a mountain slope reflecting decreasing air temperature. However, inherent soil biochemical properties (quality of organic matter and soil microbe profile) may also affect the decreasing soil N mineralization. We analyzed how temperature and inherent soil organic matter quality affect soil N mineralization rates using the elevation gradient of Yakushima with a “common‐site” approach with multiple incubation temperatures. We collected topsoils from seven forests at seven different elevations along 170–1,550 m a.s.l and incubated them under each of four temperatures at 15, 20, 25 and 30°C for 10 days in the lab. We also measured soil microbial biomass and heterotrophic soil respiration rates. Net soil N mineralization rates incubated at 15, 25 and 30°C decreased significantly linearly with increasing elevation of the origin of the soil samples at the same temperature and the intercepts of the regression lines were similar among incubation temperatures 15, 20 and 25°C. These results indicated that in situ net N mineralization rates are regulated primarily by quality of soil organic matter in our sites. Soil phenolics/N ratios increased with increasing elevation reflecting the vegetation shift along elevation and significantly negatively correlated to net soil N mineralization rates incubated at 15°C. We conclude that elevationally differentiated vegetation and associated inherent soil properties exert strong influences on net soil N mineralization rates on Yakushima Island.

Phylogenetic analyses reveal that simian foamy virus isolated from Japanese Yakushima macaques (Macaca fuscata yakui) is distinct from most of Japanese Hondo macaques (Macaca fuscata fuscata)

Japanese macaque (Macaca fuscata) is an indigenous Old World monkey (OWM) species that inhabits the Japanese archipelago. There are two subspecies of Japanese macaque: Yakushima macaque (M. f. yakui) which inhabits Yakushima Island exclusively, and Hondo macaque (M. f. fuscata) which inhabits the mainland of Japan. Yakushima macaque is considered to be branched off from a certain parental macaque group that had inhabited the mainland of Japan. However, the process of sub-speciation of the Yakushima macaque is still unclear at present. In this study, to gain new insight into the process of sub-speciation of Japanese macaque, we utilized the simian foamy virus (SFV) as a marker. SFVs are found in virtually all primates except humans and undergo species-specific cospeciation with the hosts. The phylogenetic analysis of conserved regions of the env gene in SFVs remarkably resembled that of the OWMs with high statistical confidence. The phylogenetic analyses also indicated that there are four (1–4) genotypes among Asian OWMs investigated. SFVs derived from Asian OWMs except Yakushima macaque were classified as genotypes 1–3, whereas SFVs isolated from all Yakushima macaques and one Hondo macaque were classified as genotype 4. Interestingly, genotype 4 was firstly branched off from the rest of the genotypes, which might indicate that the macaques infected with genotype 4 SFV were derived from the “older” population of Japanese macaques. The high prevalence of genotype 4 SFVs among Yakushima macaque might reflect the possibility that they are a descendant of the population settled earlier, which has been geographically isolated in Yakushima Island.

Growth and habitat use of two anguillid eels, Anguilla marmorata and A. japonica, on Yakushima Island, Japan

Tropical eels, Anguilla marmorata, and temperate eels, Anguilla japonica, coexist in rivers on Yakushima Island, southern Japan. Differences in growth rates and habitat use of these species were examined by conducting surveys at 14 stations in seven river systems of the island. Anguilla marmorata (n = 93) were collected from all seven river systems surveyed, four along the eastern coast and three along the western coast, while A. japonica (n = 52) were collected only from the three river systems on the western coast. Only one of the two species was captured at any given sampling station, but both species were collected from a concrete-paved channel of a small river. Anguilla marmorata occurred in fast-flowing river mainstems and tributaries, where the substratum comprised large rocks, while A. japonica frequented irrigation channels and stagnant reservoirs, where the substratum comprised smaller rocks, sand, or mud. Comparison of von Bertalanffy growth curves suggested that A. marmorata in Yakushima Island grows slower than A. japonica and its conspecifics in tropical regions. The mean gonadosomatic indices of female A. marmorata from Yakushima Island were also lower than those of its tropical conspecifics. The slow growth of A. marmorata in Yakushima Island might be a result of the cool and oligotrophic environment near the northern limit of their geographic distribution and environmental tolerance.

First Record on “Rump-rump Contact” Behavior between Males in wild Japanese Macaques (<i>Macaca fuscata</i>) on Yakushima Island

First Record on “Rump-rump Contact” Behavior between Males in wild Japanese Macaques (<i>Macaca fuscata</i>) on Yakushima Island

Diversity of corticolous myxomycetes in the last glacial refugia of Cryptomeria japonica in Japan

<em>Cryptomeria japonica</em>, commonly known as Japanese cedar, is now widely distributed from glacial refuges to the entire Japanese archipelago, after the last ice age. The bark surface provides a habitat for many corticolous myxomycetes. Although corticolous myxomycetes are known to prefer tree species, the association between myxomycete distribution and host tree (<em>C. japonica</em>) divergence across the refuges has not been investigated. In this study, myxomycete communities in five refuges were assessed and compared with those in 14 peripheral areas. Bark samples were collected from at least 10 trees per site and were subjected to the moist chamber culture method (10 Petri dishes per tree) to examine the myxomycete fruiting bodies strictly. Environmental variables such as geographical location, climate condition, and bark traits (tree size, bark pH, and electric conductivity) were measured. Fruiting bodies appeared in 91% of the cultures, and 32 taxa (31 species and one varie ty) were recorded. Comparison of the communities between refuges and peripheral sites showed six myxomycete species, Arcyria cinerea, <em>Macbrideola argentea</em>, <em>Cribraria minutissima</em>, <em>Clastoderma debaryanum</em>, <em>Physarum viride</em> and <em>Physarum pusillum</em>, were significantly more abundant in the refuges and these communities preserved higher species diversity. By nonmetric multidimensional scaling, the communities in the Pacific side and the Sea of Japan side were ordered based on snow cover depth, in a pattern similar to the phylogenetic distribution of the host tree. Myxomycete groups were identified in the northern region, the Sea of Japan region, and the southern region (including Yakushima Island) of Japan. Thus, the refugial tree populations preserved the myxomycete species diversity on their bark and functioned as an important hotspot for myxomycetes. The distribution of corticolous myxomycetes was associated with the diversification and biogeographical distribution history of their host tree, <em>C. japonica</em>.

Plant trait database for Cryptomeria japonica and Chamaecyparis obtusa (SugiHinoki DB): Their physiology, morphology, anatomy and biochemistry

AbstractCryptomeria japonica (sugi) and Chamaecyparis obtusa (hinoki) are major Japanese timber species whose plantation area accounts for 44 and 25%, respectively, of the plantation forests in Japan. Physiology, anatomy and ecology of the species have been intensively studied for this half century, which now forms a huge stock of information. These data, however, were scattered in diverse sources, including papers, bulletins of research institutes, reports of other kinds and books, and were presented in nonstandardized, diverse styles in each source. This paper provides a database (SugiHinoki DB) that compiles 177 plant traits of sugi and hinoki from 364 primary sources published since 1950. The compiled traits include physiological, morphological, anatomical and biochemical features that are recognized as relevant to life history strategies, vegetation modeling and global change responses. Collected data have been obtained under different environmental conditions, for plants with different ages and for organs with a different age or different position, which provide information of within‐species variation for a given trait. Each data entry is accompanied by detailed ancillary information describing the site of measurement, stand of measurement and detailed measurement conditions, which help users account for data variations as a consequence of phenotypic plasticity and genetic variations and to filter data. To provide data in a consistent format, the data and the ancillary information were standardized, and units were converted. After data compilation, outliers were detected by calculating interquartile range for each trait per each species. As of August 2019, SugiHinokiDB contains 24,683 data entries (16,410 for sugi, 8,273 for hinoki). As sugi and hinoki are major plantation species in Japan, the data mostly came from study sites in Japan (from Hokkaido in the north to Yakushima island in Kyushu to the south) but were also obtained from arboretums or plantation forests in Taiwan, Korea and China. Data were largely obtained from plants in plantation forests but also from plants in natural forests and under experimental conditions. The improved availability of trait data offered by SugiHinokiDB provides new research opportunities, such as the intensive parameterization of vegetation models for a more accurate prediction of climate change impacts.

Antiprotozoal and antihelminthic properties of plants ingested by wild Japanese macaques (Macaca fuscata yakui) in Yakushima Island.

Primates forage on a variety of plant parts to balance their dietary intake to meet requirements of energy, nutrition and maintenance, however the reason(s) leading them to ingest some plants which have no nutritional value and/or contain bioactive or even toxic secondary metabolites is recently gaining closer attention. The growing literature suggests that primates consume plants for medicinal purposes (self-medication) as well, particularly when infected with parasites and pathogens (bacteria, viruses, microbes). Interestingly, some of the plants they consume are also used by humans for similar purposes or may have potential uses for humans. As part of a 16-month study of the parasite ecology of a sub-species of Japanese macaques (Macaca fuscata yakui) on the island of Yakushima, we surveyed their feeding habits and collected a subset of plants and plant parts observed being ingested by macaques. The ethnomedicinal value of these plants was surveyed and methanolic extracts of 45 plant parts were tested in vitro against important parasites of humans, including four protozoan parasites Plasmodium falciparum, Trypanosoma brucei rhodesiense, T. cruzi and Leishmania donovani, and the trematode flatworm Schistosoma mansoni. Potential toxicity of the extracts was also assessed on mammalian cells. A wide range of ethnomedicinal uses in Asia for these plants is noted, with 37% associated with the treatment of parasites, pathogens and related symptoms. Additionally, the 45 extracts tested showed broad and significant activity against our test organisms. All extracts were active against T. b. rhodesiense. The majority (over 80%) inhibited the growth of P. falciparum and L. donovani. Half of the extracts also displayed antiprotozoal potential against T. cruzi while only several extracts were active against both larval and adult stages of S. mansoni. Cytotoxicity was generally low, although several extracts lacked specific toxicity to test parasites. Our results indicated a number of plants and their parts to have antiparasitic activity not previously reported in the ethnopharmacological literature. Enhanced understanding of the primate diets, particularly during periods of intensified parasite infection risk may help to further narrow down plants of interest for lead compound development. The study of animal self-medication is a complementary approach, with precedence, to drug discovery of new lead drug compounds against human parasitic diseases.

Genetic diversity and demographic history of introduced sika deer on the Delmarva Peninsula.

The introduction of non‐native species can have long‐term effects on native plant and animal communities. Introduced populations are occasionally not well understood and offer opportunities to evaluate changes in genetic structure through time and major population changes such as bottleneck and or founder events. Invasive species can often evolve rapidly in new and novel environments, which could be essential to their long‐term success. Sika deer are native to East Asia, and their introduction and establishment to the Delmarva Peninsula, USA, is poorly documented, but probably involved ≥1 founder and/or bottleneck events. We quantified neutral genetic diversity in the introduced population and compared genetic differentiation and diversity to the presumed source population from Yakushima Island, Japan, and a captive population of sika deer in Harrington, Delaware, USA. Based on the data from 10 microsatellite DNA loci, we observed reduced genetic variation attributable to founder events, support for historic hybridization events, and evidence that the population did originate from Yakushima Island stocks. Estimates of population structure through Bayesian clustering and demographic history derived from approximate Bayesian computation (ABC), were consistent with the hypothesized founder history of the introduced population in both timing and effective population size (approximately five effective breeding individuals, an estimated 36 generations ago). Our ABC results further supported a single introduction into the wild happening before sika deer spread throughout the Delmarva. We conclude that free‐ranging sika deer on Delmarva are descended from ca. five individuals introduced about 100 years ago from captive stocks of deer maintained in the United Kingdom. Free‐ranging sika deer on Delmarva have lost neutral diversity due to founder and bottleneck events, yet populations have expanded in recent decades and show no evidence of abnormalities associated with inbreeding. We suggest management practices including increasing harvest areas and specifically managing sika deer outside of Maryland.

Perceptions of Multiple Stakeholders about Environmental Issues at a Nature-Based Tourism Destination: The Case of Yakushima Island, Japan

The success of nature-based tourism destinations depends on the sustainable use of common pool resources (CPRs). More often than not, tourism demands compete for these resources, exerting pressure on them, resulting in decline of the CPRs. Managing tourism and environmental resources has become extremely important, but also more complex, as the interests of different stakeholders are intertwined across international, national, and local levels. Hence, this study aimed to investigate how stakeholder groups perceive the issues relating to the environment using Yakushima Island, Japan for a case study. Quantitative data were collected by administering a questionnaire to residents and tourism practitioners, while qualitative data were gathered through semi-structured interviews conducted with organizations involved with tourism and environmental management in Yakushima. The study reveals that the underlying environmental issues in Yakushima result from an increase in tourists and controversial management of deer populations. Both residents and tourism practitioners indicated that more trash in the community was the most significant impact of tourism on the environment. Some perceptions were contradictory. Management authorities noted an increase in the deer population, which needs to be controlled to prevent damage to natural vegetation. Most tour guides reported a decrease in the sighting of deer along hiking trails, frustrating the genuine expectations of the tourist. The connection of the deer issue to tourism turned out to be very complex, as an overabundance of deer endangers parts of the vegetation tourists come to enjoy, while at the same time deer are an important part of the tourists’ experience. Different perceptions on deer by different stakeholders add to this complexity, which needs to be taken into consideration for proper management of tourists and deer in the future.

A new genus and species of Stygarctidae (Heterotardigrada: Arthrotardigrada) from Yaku-Shin-Sone bank (Northwest Pacific)

A marine armoured tardigrade, Hansenarctus toyoshiomaruae gen. et sp. nov., is described from Yaku-Shin-Sone bank, south of Yakushima island, Northwest Pacific. It belongs to the family Stygarctidae Schulz, 1951 for its five-lobed head, cuticular plates, and non-digitate claws, but a combination of the following character states warrants the erection of the new genus: the semi-globular secondary clavae, sub-divided lateral lobes of the head, antero-dorsal, postero-dorsal, and latero-dorsal processes on the dorsal plates except for the caudal plate, two tapering lateral processes (one pair) on each body plate, four lateral processes (two pairs) on the caudal plate, intersegmental regions between dorsal plates, looped seminal receptacles without additional cuticular structures at the openings, and four claws with the internal ones bearing dorsal spurs. Its phylogenetic position is briefly discussed based on morphology and the following topology was suggested for Stygarctidae: (Megastygarctides, (Neostygarctus, (Faroestygarctus, Hansenarctus gen. nov., (Mesostygarctus, Pseudostygarctus), (Parastygarctus, Prostygarctus, Stygarctus)))). Stygarctid genera (excluding Megastygarctides and Neostygarctus) share a synapomorphic state: the presence of exteriorly projected apophyses in the pharyngeal bulb.

Restorement of early 19th century’s Geomagnetic declinations in Japan, from Tadataka Inoh’s survey azimuth ledger

Abstract. The Santou-Houi-Ki is a national treasure of Japan recorded by Japanese cartographic surveyor Tadataka Inoh in 1800 to 1816, consist of 67 volumes survey ledger to produce the first survey map of Japan, called “Coastal Area Map of great Japan,” or Inoh map (1 : 36000, 1 : 216000, 1 : 432000).In the Santou-Houi-Ki estimate 200,000 magnetic compass survey azimuth data by accuracy of 0°05′ unit were written, with the name or short description of magnetic compass survey reference point and target points. Inoh’s team carried out the survey did not apply the correction of magnetic declination. Because before his survey, Inoh tried to observe magnetic declination in Edo (Tokyo) was nearly zero. Inoh conducted the survey on the assumption that the influence of magnetic declination to survey map of Japan is at least. The surveyed region extends from North eastern coast of Hokkaido Island to Yakushima Island in western Japan. We start analysis, check the outline of reference point and target points from the name or the description of reference point and target points, the survey azimuth recorded in Santou-Houi-Ki, and Inoh’s survey diary, Inoh’s maps, modern survey map, today’s survey map or local source books. We execute interdisciplinary and simultaneous analysis of geomagnetic declination, real azimuth, precise position of the survey execution point and target points (latitude and longitude less than 0.1 second). And add the historical importance of each precise position of survey reference point. Calculate backward the precise position of survey reference point, where the value of magnetic declination, subtracting the magnetic survey azimuth from the true azimuth to any target points is similar or approximate. We cannot read the precise content of national treasure Santou-Houi-Ki without this interdisciplinary simultaneous analysis. We tried to analysis at 227 points in Japanese archipelago, the distribution of magnetic declination and precise position of the survey reference points and target points in early 19 century’s Japan are gradually elucidated. When we compare the analysis of declination from Santou-Houi-Ki to Noaa’s Historical Declination Viewer, NOAA’s progress of declination west is always 5 to 6 years late than the analysis of Santou-Houi-Ki. And differences are more remarkable in western Japan. We must supply the analysis data from Santou-Houi-Ki to NOAA.

Chelonocytherois omutai gen. et sp. nov. (Crustacea: Ostracoda) from the back of loggerhead sea turtles.

Chelonocytherois omutai gen. et sp. nov., is found on the back of female loggerhead sea turtles on the nesting beach of the Yakushima Island, Kagoshima Prefecture, Japan. The present study provides the first species-level identification and description of Ostracoda as sea turtle epibionts. The new genus and species, which belongs to the family Paradoxostomatidae Brady and Norman, 1889, can clearly be distinguished from other genera by the morphology of the carapace and the appendages. Especially, the quite large sieve structure on the pore system of the carapace is characteristic to this genus. Although a similar structure is also found in the commensal ostracod genus Redekea de Vos, 1953, the new genus has distinctive mandibular and maxillular morphologies. From examination of the appendages, C. omutai gen. et sp. nov. seems to be an epibiotic species associated with sea turtles, but not a strictly commensal species. Additionally, the nearly complete 18S rRNA gene sequence is determined for C. omutai gen. et sp. nov. for future molecular phylogenetic studies. Since the sea turtles migrate across the oceans in their ontogenetic stages, they may play a role as a long-distance dispersal vector for C. omutai gen. et sp. nov.

Seasonal and annual variations in egg mass and clutch size for Loggerhead Sea Turtles (Caretta caretta): experienced females lay heavier eggs

Organisms modify reproductive traits adaptively or non-adaptively in response to temporal environmental variation. Long-lived iteroparous sea turtles are ideal animals to examine such temporal shifts in resource allocation. We analyzed seasonal shifts in egg mass and clutch size for Loggerhead Sea Turtles (Caretta caretta (Linnaeus, 1758)) nesting at a temperate rookery (Yakushima Island, Japan) over a 2-year period, as well as annual variation in egg mass and clutch size over a 5-year period. Egg mass and clutch size, adjusted for female body size, did not vary seasonally at both the population and individual levels. Adjusted egg mass showed significant annual variation, despite a lack of annual variation in adjusted clutch size. Thus, Loggerhead Sea Turtles are unlikely to exhibit adaptive seasonal variation in reproductive traits, whereas they vary egg size non-adaptively in response to annual environmental conditions. Although experienced Loggerhead Sea Turtles laid heavier eggs, the annual variation in egg mass was not attributable either to breeding experience of the sampled females or to ambient temperature during follicular development, implying that other factors are involved, such as resource availability. Our data show that egg size is a more plastic reproductive trait than clutch size for Loggerhead Sea Turtles inhabiting the North Pacific.

Towards the conservation of ectomycorrhizal fungi on endangered trees: native fungal species on Pinus amamiana are rarely conserved in trees planted ex situ.

Ectomycorrhizal (ECM) symbiosis is essential for the survival of both host trees and associated ECM fungi. However, during conservation activities of endangered tree species, their ECM symbionts are largely ignored. Here, we investigated ECM fungi in ex situ populations established for the conservation of Pinus amamiana, an endangered species distributed on Yakushima Island, Japan. Our objective was to determine whether ECM fungi in natural forests are conserved in ex situ populations on the same island. In particular, we focused on the existence of Rhizopogon yakushimensis, which is specific to P. amamiana and the most dominant in natural P. amamiana forests. Molecular identification of ECM fungi in resident tree roots and soil propagule banks indicated that ECM fungal species native to natural forests were rarely conserved in ex situ populations. Furthermore, R. yakushimensis was not confirmed in any of the resident root or spore bioassay samples from the ex situ populations. Thus, ECM fungal spores may not be effectively dispersed from natural forests located on the same island. Instead, ECM fungi distributed in other geographical regions occurred more frequently in the ex situ populations, indicating unintentional introductions of non-native ECM fungi from the nurseries where seedlings were raised before transplanting. These findings imply that the current ex situ conservation practices of endangered tree do not work for the conservation of native ECM fungi, and instead may need modification to avoid the risk of introducing non-native ECM fungi near the endangered forest sites.

Inferring the demographic history of Japanese cedar, Cryptomeria japonica, using amplicon sequencing.

The evolution of a species depends on multiple forces, such as demography and natural selection. To understand the trajectory and driving forces of evolution of a target species, it is first necessary to uncover that species' population history, such as past and present population sizes, subdivision and gene flow, by using appropriate genetic markers. Cryptomeria japonica is a long-lived monoecious conifer species that is distributed in Japan. There are two main lines (omote-sugi and ura-sugi), which are distinguished by apparent differences in morphological traits that may have contributed to their local adaptation. The evolution of these morphological traits seems to be related to past climatic changes in East Asia, but no precise estimate is available for the divergence time of these two lines and the subsequent population dynamics in this species. Here, we analyzed the nucleotide variations at 120 nuclear genes in 94 individuals by using amplicon sequencing in combination with high-throughput sequencing technologies. Our analysis indicated that the population on Yakushima Island, the southern distribution limit of C. japonica in Japan, diverged from the other populations 0.85 million years ago (MYA). The divergence time of the other populations on mainland Japan was estimated to be 0.32 MYA suggesting that the divergence of omote-sugi and ura-sugi might have occurred before the last glacial maximum. Although we found modest levels of gene flow between the present populations, the long-term isolation and environmental heterogeneity caused by climatic changes might have contributed to the differentiation of the lines and their local adaptation.

Species of the Maera-clade collected from Japan. Part 2: genera Austromaera Lowry Springthorpe, 2005 and Quadrimaera Krapp-Schickel Ruffo, 2000 (Crustacea: Amphipoda: Maeridae).

One species of Austromaera Lowry Springthorpe, 2005 and four species of Quadrimaera Krapp-Schickel Ruffo, 2000 included in the Maera clade, are described from Japan. Austromaera ariakensis sp. nov. is described, based on collections from Ariake Sea and can be distinguished from its congeners by the acutely produced coxa 1 and the merus of gnathopod 2 with a small posterodistal spine. Quadrimaera gotoensis sp. nov. from Goto Islands in Nagasaki Prefecture has a small quadrate excavation on the middle palmar margin of the male gnathopod 2. This new species is different from Q. mirandella Appadoo, Myers Fagoonee, 2002 having such an excavation, in the larger posterodistal tooth of the male gnathopod 2 propodus and the wider bases of the pereopods 5-7. Quadrimaera pacifica (Schellenberg, 1938) was collected from many localities from Iwate Prefecture to Ariake Sea. This species is characterized by the transverse palm of the male gnathopod 2 with the large posterodistal tooth, the small rounded excavation in the middle and the anterior lobe narrower and produced more distally than the posterior lobe. Morphology of Q. pacifica is variable in the posterior excavation of the male gnathopod 2 palm, the uropod 3 rami and the distal end of the telson. Quadrimaera quadrimana (Dana, 1853) from the south of Yakushima Island in Kagoshima Prefecture has a distinct palm of the male gnathopod 2 with three excavations. Quadrimaera setibasis sp. nov. collected from the intertidal zone in Osaka Prefecture has a setose basis of the pereopod 6 like Q. schellenbergi (Ruffo 1938), but the bases of the pereopods 5 and 7 are not setose. A key to species of Austromaera in the world is provided.