Amami Islands Research Articles

Ancient Ryūkyū: An Archaeological Study of Island Communities by Richard Pearson (review)

Reviewed by: Ancient Ryūkyū: An Archaeological Study of Island Communities by Richard Pearson Boyd Dixon and Alexandra Garrigue Ancient Ryūkyū: An Archaeological Study of Island Communities. Richard Pearson. Honolulu: University of Hawai‘i Press, 2013. 396pp, 42 illustrations in black and white, 9 appendixes, 1 color frontispiece. ISBN 978-0-824-83712-9. Cloth US$ 55. Richard Pearson’s Ancient Ryūkyū: An Archaeological Study of Island Communities examines the human occupation of the Ryūkyū archipelago and its relations with its neighbors, from its earliest peopling in the Pleistocene era, circa 32,000 years before present (b.p.), to the subjugation of the Ryūkyū Kingdom by a Japanese feudal clan in 1609. The author argues that during the Palaeolithic and Neolithic periods, the diverse archipelago constituting the Ryūkyū was likely colonized more than once by small groups of hunter-gatherers coming from the north, south, or west. A distinct maritime-focused culture developed over the lengthy Shell-mound period. The exchanges initiated during this period continued in new forms through the following Gusuku period, when agriculture was adopted and international trade with other kingdoms emerged. This book vastly updates Pearson’s previous volume, Archae ology of the Ryūkyū Islands (University of Hawai‘i Press, 1969), bringing together four decades of recent archaeological literature, much of it written by Japanese scholars, to document the growing material record of human occupation in the archipelago over time. After introducing the reader to the regional archaeology and palaeogeography of the Ryūkyū Islands (chapters 1 and 2), the author discusses Pleistocene peopling in chapter 3. Correlations are made between sites and processes of migration, colonization, and assimilation. During the regression of the late and last glacial maxima between 32,000 and 10,000 b.p., it seems that few Homo sapiens dared to cross the narrow water gaps that probably remained between the continent and the Ryūkyū Islands in the Tokara Strait—Kerama Gap and Yonaguni Trench. They might have followed deer, the fossilized bones of which are frequently found in geological contexts sometimes in association with human remains. The author acknowledges the absence of archaeological sites with in situ artifacts for this period. After an archaeological void of at least four millennia during which the human population of the Ryūkyū might have become extinct, it was not until roughly 7000 b.p. that coastal reefs and upland forests stabilized enough to again attract visitors from neighboring islands. Modern genetic evidence and palaeobiological studies of skeletal remains show physical discontinuities between late Pleistocene and later populations. They do not expose any close affinity between Ainu (northern Japanese) and Ryūkyū populations, which should have been the case if they both had been direct descendents of Jōmon peoples, as widespread theories suggest. Chapters 4 through 6 span the long Shell-mound period between 7000 and 1100 b.p. [End Page 116] when most Ryūkyū islands were inhabited, from Tanegashima in the north to the Sakishima Islands in the south. During this period, hunter-gatherer colonization from Kyūshū and subsequent interaction between north-central Ryūkyū and southern Japan or farther became undeniable. As the period name suggests, early colonists appear to have focused on coastal zones near accessible maritime resources. Differing ceramic sequences between island clusters suggest small groups arrived in sporadic intervals and adapted to local conditions independently, rather than there having been a coordinated or continuous migration from the north. The book proposes a broad description of each known ceramic type. The main vessel forms are deep jars for cooking and globular jars for storage. Vessels were first plain, then fingernail impressions appeared, followed by a large variety of decorative patterns. Both vessels imported from Kyūshū and those locally produced have been found, suggesting constant interaction and probably sporadic migration over time. The author argues that colonization in northern and central Ryūkyū probably constituted several phases, including early exploration, sojourn, and colonization. In this process, the Amami Islands, located between Kyūshū and Okinawa Island, probably played a key role. By 3500 b.p., the Ryūkyū inhabitants started to develop a strong local identity, but conserved links with southern...

奄美群島におけるアリモドキゾウムシおよびイモゾウムシの分布（2010-2011年）

The geographical distribution of the sweetpotato weevil, Cylas formicarius and the West Indian sweetpotato weevil, Euscepes postfasciatus were investigated on sweetpotato, Ipomoea batatas and wild host plants, I. india and I. pes-caprae on the Amami Islands except Kikai Island during 2010 to 2011. The number of C. formicarius male adults was determined using simple sticky traps with synthetic sex pheromone at 235 sites during November 2010 to February 2011. The occurrence of the two weevils were investigated at 109 sweetpotato fields and 97 creeping colonies of wild host plants, I. india and I. pes-caprae, sites during November 2010 to February 2011. Both weevil species were found in all islands of the Amami Islands. This was consistent with the result of 1997-1998, and the distribution of both weevils species have not changed on the Amami Islands. The occurrence of E. postfasciatus was on the increase from 1997. On Okinoerabu Island, the number of male adults of C. formicarius captured using pheromone traps were fewer than the other islands.

奄美諸島におけるカンキツグリーニング病の発生調査 （第3報 第2期調査後の感染樹発生の推移）

奄美諸島におけるカンキツグリーニング病の発生調査 （第3報 第2期調査後の感染樹発生の推移）

Molluscs drifted on the coast of Yoron-jima, Amami Islands, southwestern Japan

Molluscs drifted on the coast of Yoron-jima, Amami Islands, southwestern Japan

Description of two species of Protella Dana, 1852 (Crustacea: Amphipoda): P. gracilis Dana, 1853, from Balabac Strait, the Philippines, and P. amamiensis, new species, from southern Japan

Two species of Protella Dana, 1852 (Crustacea: Amphipoda) are described in detail: P. gracilis Dana, 1853, based on type specimen collected from Balabac Strait, separating the Philippines and Borneo in the tropical Indo-Pacifi c and deposited in the Museum of Comparative Zoology, Harvard University; and P. amamiensis, new species, collected from Amami Islands, Ryukyu Archipelago, southern Japan, situated at the border of temperate and tropical regions in the northern Pacifi c. Protella amamiensis, new species, differs from P. gracilis in its 2-articulate pereopods 3 and 4, small penes, and elongated uropod 1.

Tropical drift seeds stranded on Ikeji beach, Kikai-jima, Amami Islands, southwestern Japan

Tropical drift seeds stranded on Ikeji beach, Kikai-jima, Amami Islands, southwestern Japan

Differential population responses of native and alien rodents to an invasive predator, habitat alteration and plant masting

Invasive species and anthropogenic habitat alteration are major drivers of biodiversity loss. When multiple invasive species occupy different trophic levels, removing an invasive predator might cause unexpected outcomes owing to complex interactions among native and non-native prey. Moreover, external factors such as habitat alteration and resource availability can affect such dynamics. We hypothesized that native and non-native prey respond differently to an invasive predator, habitat alteration and bottom-up effects. To test the hypothesis, we used Bayesian state-space modelling to analyse 8-year data on the spatio-temporal patterns of two endemic rat species and the non-native black rat in response to the continual removal of the invasive small Indian mongoose on Amami Island, Japan. Despite low reproductive potentials, the endemic rats recovered better after mongoose removal than did the black rat. The endemic species appeared to be vulnerable to predation by mongooses, whose eradication increased the abundances of the endemic rats, but not of the black rat. Habitat alteration increased the black rat's carrying capacity, but decreased those of the endemic species. We propose that spatio-temporal monitoring data from eradication programmes will clarify the underlying ecological impacts of land-use change and invasive species, and will be useful for future habitat management.

Monitoring the effects of forest clear-cutting and mongoose Herpestes auropunctatus invasion on wildlife diversity on Amami Island, Japan

AbstractWildlife populations on Amami Island, Japan, have been affected by forest clear-felling and the introduction of alien species, in particular the mongoose Herpestes auropunctatus. We used monitoring data collected over 24 years to track changes in the population sizes of five species of mammals and 20 species of birds. We assigned species to the following groups: indigenous, rare, insectivorous, negatively affected by forest clear-cutting, and negatively affected by mongoose invasion. We examined trends in each group at four time points between 1985 and 2010 using two methods: species abundance estimates and the Living Planet Index. We then assessed the usefulness of these methods as tools for conservation planning. Inspecting species individually we identified four main patterns of abundance change: (a) an increase from the first to the last census period, (b) an increase in all periods except 2009–2010, (c) a decrease from 1985–1986 to 2001–2002 but an increase in 2009–2010, and (d) a decrease in all census periods. We observed certain relationships between these patterns and the species groups assigned as above. According to the Living Planet Index the group negatively affected by forest clear-cutting did not show significant recovery and the groups of rare species and species negatively affected by mongoose recovered to c. 40% of the original level after a sharp decline during 1985–2002. The Living Planet Index is a more useful tool for assessing the urgency of particular conservation needs, although limited information on species abundance reduces its representativeness for some groups.

An Attempt at Captive Breeding of the Endangered Newt Echinotriton andersoni, from the Central Ryukyus in Japan.

Simple SummaryWe naturally bred the endangered Anderson’s crocodile newt (Echinotriton andersoni) and tested a laboratory farming technique using near-biotopic breeding cages with several male and female pairs collected from Okinawa, Amami, and Tokunoshima Islands. This is the first published report of successfully propagating an endangered species by using breeding cages in a laboratory setting for captive breeding. Our findings on the natural breeding and raising of larvae and adults are useful in breeding this endangered species, and can be applied to the preservation of other similarly wild and endangered species.Anderson’s crocodile newt (Echinotriton andersoni) is distributed in the Central Ryukyu Islands of southern Japan, but environmental degradation and illegal collection over the last several decades have devastated the local populations. It has therefore been listed as a class B1 endangered species in the IUCN Red List, indicating that it is at high risk of extinction in the wild. The species is also protected by law in both Okinawa and Kagoshima prefectures. An artificial insemination technique using hormonal injections could not be applied to the breeding of this species in the laboratory. In this study we naturally bred the species, and tested a laboratory farming technique using several male and female E. andersoni pairs collected from Okinawa, Amami, and Tokunoshima Islands and subsequently maintained in near-biotopic breeding cages. Among 378 eggs derived from 17 females, 319 (84.4%) became normal tailbud embryos, 274 (72.5%) hatched normally, 213 (56.3%) metamorphosed normally, and 141 (37.3%) became normal two-month-old newts; in addition, 77 one- to three-year-old Tokunoshima newts and 32 Amami larvae are currently still growing normally. Over the last five breeding seasons, eggs were laid in-cage on slopes near the waterfront. Larvae were raised in nets maintained in a temperature-controlled water bath at 20 °C and fed live Tubifex. Metamorphosed newts were transferred to plastic containers containing wet sponges kept in a temperature-controlled incubator at 22.5 °C and fed a cricket diet to promote healthy growth. This is the first published report of successfully propagating an endangered species by using breeding cages in a laboratory setting for captive breeding. Our findings on the natural breeding and raising of larvae and adults are useful in breeding this endangered species and can be applied to the preservation of other similarly wild and endangered species such as E. chinhaiensis.

Taxonomic reexamination of Portulaca okinawensis (Portulacaceae) in<br />the Ryukyu Archipelago of Japan based on molecular and morphological data

We used molecular phylogenetic and morphological data to reexamine the taxonomic status of Portulaca okinawensis (≡ P. pilosa subsp. okinawensis) endemic to the central Ryukyu islands, southwestern Japan. Our molecular analyses showed that P. okinawensis is monophyletic, sister to the clade of P. psammotropha and P. tuberosa and it is not closely related to P. pilosa subsp. pilosa. Two subclades, one comprising plants from the Okinawa Islands and the other from the Amami Islands, were recognized. The plants from the Okinawa Islands had more than 20 stamens, orange-yellow nallowly obovate to oblanceolate petals, and reddish-green stems (as the holotype), while the plants from the Amami Islands had less than 20 stamens, lemon-colored obovate petals, and bright-green stems. The molecular and morphological data support a taxonomic treatment of Walker & Tawada (1951) regarding P. okinawensis as a separate species, also suggesting that the plants from the Amami and Okinawa islands should be treated as different taxa. A new variety Portulaca okinawensis var. amamiensis was here described.

Systematic studies on the Pompilidae occurring in Japan: Genus Platydialepis Haupt (Hymenoptera: Pompilidae: Pepsinae)

AbstractGeneric characters of Platydialepis Haupt, 1941 are presented. A new species of the genus, P. amamiensis sp. nov. from the Amami Islands, the Ryukyus, Japan, is described, and another species of the genus, P. ryoheii Ishikawa, 1957, distributed in Honshu, Shikoku and Kyushu, Japan, is redescribed. Their biological notes are also given. A new combination is proposed: Platydialepis taiwaniana (Tsuneki, 1989) (=Malloscelis taiwaniana Tsuneki).

Host plant manipulation by fig gall midges (Diptera: Cecidomyiidae) which induce emergence projections on flower galls in the syconia of Ficus microcarpa (Moraceae)

AbstractWe observed that unique projections developed from female flower galls induced by three unidentified cecidomyiid species in the syconia of Ficus microcarpa (Moraceae) on Okinawa and Amami Islands, Japan. The three cecidomyiids (sp. 1, 2 and 3) were tentatively distinguished by the differences in the shape of the projections. The projection of sp. 1 started to develop from the bottom of each gall before emergence, broke the skin of the syconium, and developed finally up to 5–6 mm in length within 6–8 h. During this period, the pupa oriented its head towards the bottom of the gall. After the projection fully elongated, the pupa pushed open the bottom of the projection with its head. The projection was easily removed from the gall at the base. The pupa quickly crawled half way out of the gall through the opening at the bottom of the projection and an adult then emerged. The projection did not develop when other hymenopteran gall inhabitants emerged. The projection was derived from plant tissues consisting of a mass of small square cells in the basal and distal portions and regularly arranged long cells in the middle portion. No projection was induced by the application of gibberellin's paste to the bottom of syconia. The gall midge seemed to manipulate the fig plant to develop the projection before emergence, so that the pupa can easily pass through the sticky epidermis of the syconium. The emergence of sp. 2 and 3 could not be intensively observed.

Reconstruction and prediction of invasive mongoose population dynamics from history of introduction and management: aBayesian state‐space modelling approach

Summary An understanding of the underlying processes and comprehensive history of invasive species is necessary to assess the long‐term effectiveness of invasive species management. However, continuous, long‐term labour‐intensive population surveys on invasive species are often not feasible. Thus, it is important to learn about their dynamics through management action and its consequences. Amami Island, Japan, has an ongoing large‐scale and long‐term eradication programme of invasive small Indian mongooses. To estimate the long‐term pattern of population size and the parameters determining the dynamics, including anthropogenic removal, we applied a surplus‐production model within a Bayesian state‐space formulation incorporating the initial population size, number of captures and capture effort. Using the estimated process model directly, we conducted stochastic simulations to evaluate the feasibility of eradication. Estimated 32‐year annual capture probability of mongooses has increased since their introduction. The population size started to decline in 2001; mean population size in 2000 was 6141 (95%CI: 5415–6817), and declined to 169 (95%CI: 42–408) by 2011. Parameter estimates of a Weibull catchability model indicated that there was large individual heterogeneity in the probability of being captured, and per‐effort capture probability declined with an increase in annual capture effort. The simulation study indicated that the eradication feasibility in 2023 would be over 90% if the same annual capture effort is upheld as in 2010 (2 075 760 corrected trap‐days). However, increasing annual capture effort would have little effect on shortening the time to eradication. Synthesis and applications. A hierarchical model that incorporates multiple types of data to reveal long‐term population dynamics has the potential to be updated with the outcomes of control efforts, and will enhance adaptive management of invasive species. This approach will offer valuable information about trade‐offs between time to eradication success and effort per unit time in a long‐term eradication project, and the length of time needed to continue management actions to achieve eradication success.

An Aspect of Disaster in Tokunoshima, Amami Islands

An Aspect of Disaster in Tokunoshima, Amami Islands

Geographical Diversity of Japanese Papilio Butterflies Inferred from the Number of Contact Chemosensillum on the Fifth Foretarsal Segments

The numbers of contact chemosensillum on ventral side of fifth foretarsal segments of Japanese Papilio butterflies were determined by scanning electron microscope observation. P. bianor, P. helenus, P. protenor and P. memnon exhibited geographical diversity for this character among mainland Japan, Amami Islands, Okinawa Islands and Yaeyama Islands populations. This characteristic was useful for reconfirming the geographical variations proposed by the wing color patterns and genetic characteristics of each these species. This characteristic also uncovered hidden geographical variations and phylogenetic structures of P. machaon, P. xuthus, P. maackii, P. macilentus and that of P. memnon on mainland Japan and that of P. protenor on Okinawa Islands. Also discussed are possible causes for the apparent phylogeny disparities between this report and other previous studies including DNA analyses.

奄美大島・加計呂麻島におけるシガテラ原因魚の毒組成解析

Ciguatoxins (CTXs) responsible for ciguatera fish poisoning (CFP) in Amami Islands, Kagoshima, Japan in 2008 were determined by LC-MS/MS analysis. Ciguatoxin-1B (CTX1B), 54-deoxyCTX1B, and 52-epi-54-deoxyCTX1B were detected in Variola louti and Lutjanus monostigma. The toxin profile distinctly differed from that of a CFP-related fish from Miyazaki, which mainly contained ciguatoxin-3C type toxins. Toxin profiles were species-specific, as observed in fish from Okinawa. The LC-MS/MS and mouse bioassay (MBA) methods produced comparable data, though 54-deoxyCTX1B was not taken into consideration owing to the lack of toxicity data. To improve assessment, toxicity data for this compound are needed. A reef fish caught on the same occasion and judged nontoxic by MBA (<0.025 MU/g) was found to contain low levels of CTX, indicating a potential risk for CFP.

奄美諸島喜界島におけるモズの繁殖

奄美諸島喜界島におけるモズの繁殖

Species-diverse coral communities on an artificial substrate at a tuna farm in Amami, Japan

Tuna-farming is expanding worldwide, necessitating the monitoring/managing of its effects on the natural environment. In Japan, tuna-farming is conducted on coral reefs that have been damaged by mass-bleaching events and crown-of-thorns starfish (COTS) outbreaks. This study focused on the coral community on an artificial substrate of tuna-farm to reveal the possible effects of tuna-farming on the natural environment. Corals flourished on ropes suspended in the farm in the Amami Islands, southern Japan. These were moored 3 m below the sea-surface in 50-m-deep water. The coral community on the rope was analyzed and compared with those on natural substrata on two adjacent COTS-damaged reefs and with that in a protected reef. Corals were monitored throughout a year. Sixty coral species grew on the ropes, that corresponds to 27.3% of the 220 species known from Amami. The coral community was unique, dominated by massive faviid corals. On the ropes, the water temperature rarely exceeded 30.0 °C and no corals on the rope were severely bleached or covered by sedimentation during the observations. The tuna-farm infrastructure provided corals with a suitable habitat, and species-rich coral communities were established. These coral communities are an important node connecting tuna-farms and the natural environment.

Isolation and characterization of eight microsatellite loci in the Otton frog, Babina subaspera

The Otton frog, Babina subaspera, is an endangered forest frog species with unusual morphological and ecological features compared with other frogs. Eight microsatellite markers were isolated from B. subaspera and characterized with 24 individuals from Amami Islands, Kagoshima prefecture, Japan. The number of alleles observed for each locus ranged from 9 to 19 (average 13.9). The observed heterozygosity (HO) and the expected heterozygosity (HE) ranged from 0.71 to 0.92 and 0.83 to 0.92, respectively. These microsatellites will be useful for future genetic studies of B. subaspera, which will be essential in the conservation of this species.

Interpopulation variation in egg size in the winter cherry bug relative to oviposition site selection

AbstractTo investigate whether or not oviposition on substrates other than host plants (e.g., non‐host plants, abiotic materials) would affect the evolution of egg size in phytophagous insects, we studied the winter cherry bug, Acanthocoris sordidus (Thunberg) (Heteroptera: Coreidae), as a model organism for its interpopulation variation in oviposition preference. The rate of oviposition off host plants is much higher in the Amami Island population than in either the Kyoto or Kochi populations. We compared egg size and number among the three local populations from Kyoto, Kochi, and Amami Island. In addition, to evaluate the adaptive significance of larger eggs for offspring in terms of searching for host plants, we examined the relationship between egg size and first‐instar body size. We also searched for a relationship between egg size and starvation tolerance in the second instars because first instars can develop to second instars without food intake, and thus the substantial host‐searching stage is the second instar, when females lay their eggs off host plants. Females from the Amami population produced fewer larger eggs than females from either the Kyoto or Kochi population. Regardless of the local population, the body size of first instars that emerged from larger eggs was larger, and the second instars originating from larger eggs had a higher starvation tolerance. The larger body size and higher starvation tolerance should enable nymphs to disperse further, which may enhance the probability of successfully reaching host plants. These results suggest that egg size in A. sordidus may be determined in relation to its oviposition habits to maximize reproductive success, resulting in interpopulation variation in egg size.