1.

論文(リポジトリ)

論文(リポジトリ)
下瀬, 環 ; 今井, 秀行 ; Shimose, Tamaki ; Imai, Hideyuki
出版情報: Fauna Ryukyuana.  60  pp.9-15,  2021-06-09.  Ryukyu University Museum, Fujukan — 琉球大学資料館 (風樹館)
URL: http://hdl.handle.net/20.500.12000/48547
概要: 八重山諸島の石垣島で, 2018年12月16日にゴマサバScomber australasicusの成魚が水揚げされた. ゴマサバは沖縄島から記録があるものの, 八重山諸島からは初記録であるため, ここに報告する. また, サバ属Scomb erとグルクマ属RastrelligerからなるScombriniの臀鰭棘数を観察したところ, 近年普及している図鑑での数値と異なる結果が得られたので, これについても考察した.<br />A single adult specimen of Scomber australasicus was collected from Ishigaki-jima Island, Okinawa, Japan, on 16 December 2018, which represents the first specimen-based record from the Yaeyama Islands. In this paper, the number of anal-fin spines in the tribe Scombrini is also discussed. 続きを見る
2.

論文(リポジトリ)

論文(リポジトリ)
Iwamoto, Kensuke ; Chang, Chin-Wei ; Imai, Hideyuki
出版情報: Biogeography : international journal of biogeography, phylogeny, taxonomy, ecology, biodiversity, evolution, and conservation biology.  22  pp.26-34,  2020-09-20.  Biogeographical Society of Japan — 日本生物地理学会
URL: http://hdl.handle.net/20.500.12000/46909
概要: Studies have suggested that fishes with broad distribution ranges, long pelagic duration, and great mobility in their early life histories may have an advantage in their ability to return to their natal reef habitats. Siganus spinus is a siganid fish with a broad dispersal strategy, which may also exploit its great mobility to enhance self-recruitment. Variations in mitochondrial DNA sequences were analysed to estimate the genetic structure and demographic history of Siganus spinus in the West Pacific. In total, 446 nucleotide sequences, including the tRNAThr gene, the tRNAPro gene, and the first half of the control region, were analysed from 240 individuals sampled at five sites spanning the West Pacific Ocean; 37 haplotypes were identified. Our results showed significant geographic genetic structure as well as isolation by distance. Both neutrality tests and mismatch distribution indicated that the population expansion of S. spinus through the study area may have occurred in the late Quaternary. A dispersal strategy characterised by large juveniles and open-sea distribution may have contributed to a sudden population expansion after the last glacial period, along with an expansion of distribution. 続きを見る
3.

論文(リポジトリ)

論文(リポジトリ)
Tokuyama, Takenobu ; Shy, Jhy-Yun ; Lin, Hui-Chen ; Henmi, Yasuhisa ; Mather, Peter ; Hughes, Jane ; Tsuchiya, Makoto ; Imai, Hideyuki
出版情報: Crustacean Research.  49  pp.141-153,  2020-09-03.  Carcinological Society of Japan — 日本甲殻類学会
URL: http://hdl.handle.net/20.500.12000/46908
概要: The fiddler crab, Austruca lactea inhabits tidal flat areas and is widely distributed across Japan, the Korean Peninsula, China, Taiwan and northern Vietnam. Fiddler crab habitat is being lost rapidly due to human impacts and this species is currently listed as endangered in Japan. We studied the population genetic structure of A. lactea using mitochondrial DNA control region markers to define management units. A. lactea individuals were sampled from Osaka, Hiroshima and Kumamoto in Japan, and from Taichung and the Penghu Islands in Taiwan. All local samples exhibited high levels of genetic diversity, and no sampled populations showed evidence for a significant decline in effective population size that can result from population bottleneck effects. Pairwise FST estimates distinguished three discrete A. lactea populations corresponding with, the Seto Inland Sea (Osaka and Hiroshima), Kyushu (Kumamoto) and Taiwan. The three populations showed clear differences in historical population expansion times and their population dynamics after expansion. Results of the study indicate that A. lactea dispersal is limited geographically and that high levels of genetic diversity are maintained both within and among populations. 続きを見る
4.

論文(リポジトリ)

論文(リポジトリ)
畑中, ひらり ; 今井, 秀行 ; Hatanaka, Hirari ; Imai, Hideyuki
出版情報: 日本生物地理学会会報 = Bulletin of the Bio-geographical Society of Japan.  pp.60-69,  2018-12-20.  日本生物地理学会 — The Biogeographical Society of Japan
URL: http://hdl.handle.net/20.500.12000/43516
概要: This study included 508 individuals of Oryzias latipes from 15 sites in mainland Japan and 10 sites in the Ryukyu Archipelago and Taiwan used in Imai et al. (2017), and new samples from four sites in the Ryukyu Archipelago, four sites in China and South Korea, and one from hi-medaka. We developed four new PCR-RFLP nuclear DNA markers (Orla16- 185-MboI, Orla1-29-BstUI, Orla1-51-AluI, and P0Ex-HinfI) based on three universal microsatellite primer sets and an exon-primed intron-crossing (EPIC) primer set for fish. STRUCTURE analysis indicated that Amami-oshima, Iheya, Izena, Ginama, Ogimi, and Bios no Oka formed a cluster, while specimens from Fukuchi, the former Kadena Ammunition Storage area, Zamani, and other Okinawa Islands formed a different cluster. The genetic diversity of subpopulations from Fukuchi, the former Kadena Ammunition Storage area, and Zamani was higher than those from other Okinawa Islands. The individual exclusion test (>90% condition) was applied to the Okinawa Islands subpopulation using GeneClass2. It will be important to apply these genetic markers for periodical genetic monitoring of this subpopulation. 続きを見る
5.

論文(リポジトリ)

論文(リポジトリ)
Fuke, Yusuke ; Imai, Hideyuki ; 福家, 悠介 ; 今井, 秀行
出版情報: Fauna Ryukyuana.  44  pp.7-15,  2018-07-31.  Ryukyu University Museum, Fujukan — 琉球大学資料館 (風樹館)
URL: http://hdl.handle.net/20.500.12000/42406
概要: This paper reports the finding of one of the Palaemonidae freshwater prawns, Macrobrachium ustulatum, on Okinawa-jima Is land, Ryukyu Archipelago, Japan. This represents the first record of this species in this country and also the northernmost distributional record of the species. Macrobrachium ustulatum redescribed by Castelin et al. (2017) is a cryptic species of M. australe. However, there was uncertainty in the assignation of two nomina to Castelin’s et al. (2017) molecularly identified two species. Moreover, among females, it is difficult to recognize clear morphological differences between M. ustulatum and M. australe. Therefore, we examine their validity of the taxonomic identification based on DNA sequences using the mitochondrial 16S rRNA gene and the nuclear 28S rDNA gene as well as morphological analyses. Consequently, these results supported the identification of the previous study.<br />琉球列島沖縄島北部の河川から得られたテナガエビ科のMacrobrachium ustulatumの標本を記録した. これは本種の日本初記録であると同時に, 分布の北限記録となる. 本種は長らくザラテテナガエビM. australeの新参異名とされてきたが, Castelin et al. (2017) により独立種として再記載された. しかし, 分子系統解析によって認識された2種への名義の割り当ての妥当性には不明確な部分があった. そこで本報告では, 両種について形態形質とミトコンドリアDNAの16S rRNAと核DNAの28S rDNA領域を用いた相同性検索を併用することで, 先行研究で行われた分類の妥当性を検証した. その結果, 先行研究の結果を支持する証拠が得られ, それに従って両種の同定を行った. 併せて, Macrobrachium ustulatumの標準和名としてナンヨウテナガエビを提唱し, その基準標本にRUMF-ZC-4626を指定した. Macrobrachium australeの標準和名は従来通りザラテテナガエビとし, 和名の基準標本にRUMF-ZC-4645を指定した. 続きを見る
6.

論文(リポジトリ)

論文(リポジトリ)
Abdullah, Muhamad Fadry ; Cheng, Jin-Hua ; Chen, Tzyy-Ing ; Imai, Hideyuki
出版情報: Biogeography : international journal of biogeography, phylogeny, taxonomy, ecology, biodiversity, evolution, and conservation biology.  pp.61-68,  2017-09-20.  Biogeographical Society of Japan — 日本生物地理学会
URL: http://hdl.handle.net/20.500.12000/37545
概要: Ten novel di- and tri-nucleotide polymorphic microsatellite loci were identified to aid in genetic structure analysis of the widely distributed pronghorn spiny lobster, Panulirus penicillatus. Genetic variation among populations was explored, and we compared our results to those of a previous mitochondrial DNA (mtDNA) analysis (Abdullah et al. 2014) conducted in the northwestern Pacific Ocean. A total of 129 P. penicillatus individuals were collected from three localities in Japan (Hachijojima Island, Okinawajima Island and Ishigakijima Island) and one in Taiwan (Taitung). F-statistical analysis revealed no significant genetic differences among animals collected at the different localities, in agreement with data from the previous mtDNA study. The combined data suggest that high-level gene flow exists among the explored localities, probably caused by the extended planktonic larval stage and the prevailing Kuroshio Current. On the scale of the northwestern Pacific, the results obtained in both studies suggest that P. penicillatus forms a single unique panmictic population, or at least that the several breeding grounds exchange significant amounts of genetic material. 続きを見る
7.

論文(リポジトリ)

論文(リポジトリ)
Fukuchi, Jun ; Hanamura, Yukio ; Imai, Hideyuki
出版情報: Biogeography : international journal of biogeography, phylogeny, taxonomy, ecology, biodiversity, evolution, and conservation biology.  19  pp.31-34,  2017-09-20.  Biogeographical Society of Japan — 日本生物地理学会
URL: http://hdl.handle.net/20.500.12000/37548
概要: The occurrence of the shallow-water sergestid shrimp Acetes sibogae sibogae Hansen, 1919 (Crustacea, Decapoda, Sergestidae) in Japan has been confirmed. This is the first record of this species and reflects a notable northward range expansion to Okinawa-jima Island, Ryukyu Archipelago, Japan. 続きを見る
8.

論文(リポジトリ)

論文(リポジトリ)
今井, 秀行 ; 米沢, 俊彦 ; 立原, 一憲 ; Imai, Hideyuki ; Yonezawa, Toshihiko ; Tachihara, Katsunori
出版情報: 日本生物地理学会会報 = Bulletin of the Bio-geographical Society of Japan.  71  pp.121-129,  2017-01-20.  日本生物地理学会 — The Biogeographical Society of Japan
URL: http://hdl.handle.net/20.500.12000/37568
概要: The current study examined the distribution of minami-medaka (Oryzias latipes) across the Ryukyu Archipelago in Japan to assess if the Ryukyu subpopulation as described by Sakaizumi et al. (1983) may be significantly divergent. Between 2003 and 2010, O. latipes were sampled from across Japan and populations compared using two genetic markers, an allozyme locus (aspartate aminotransferase; Aat) originally screened by Sakaizumi et al. (1983) and a new PCR-RFLP mtDNA marker based on the ND1 region. Laboratory trials showed that the Ryukyu subpopulation of O. latipes crossed with the Eastern subpopulation produced viable hybrids possessing both alleles Aatb and Aatc confirming that this marker will be effective for distinguishing natural hybrids between the Ryukyu subpopulation and other subpopulations. Populations distributed from the Amamioshima Islands to the Okinawa Islands all conformed to Ryukyu subpopulation genotypes and were fixed for allele Aatc. In addition, Okinawa islands populations were discriminated for the first time successfully from other subpopulations based on haplotype 5 (PCR-RFLP marker). A population at Chinen on Okinawajima Island possessed different genotypes to other Ryukyu subpopulations suggesting that it may have resulted from an introduction from a non-native source. Genetic introgression from other non-native subpopulations of O. latipes is the first case found in the Ryukyu Archipelago. It will be important in the future therefore, to apply the genetic markers used here to periodically monitor the Ryukyu subpopulation to conserve unique regional genetic diversity. 続きを見る
9.

論文(リポジトリ)

論文(リポジトリ)
賀数, 大吾 ; 佐久本, 孟寿 ; 立原, 一憲 ; 今井, 秀行 ; Kakazu, Daigo ; Sakumoto, Takehisa ; Tachihara, Katsunori ; Imai, Hideyuki
出版情報: 日本生物地理学会会報 = Bulletin of the Bio-geographical Society of Japan.  70  pp.55-63,  2015-12-20.  日本生物地理学会 — The Biogeographical Society of Japan
URL: http://hdl.handle.net/20.500.12000/37567
概要: In May 2015, a presumed hybrid fusilier fish of the genus Pterocaesio was collected from Ie-jima Island, Ryukyu Archipel ago, Japan. It was morphologically similar to both Pterocaesio digramma and P. marri, but the species could not be clearly identified. To determine if it was a hybrid, we developed a PCR-RFLP marker that could distinguish these two species. After amplifying ITS-1 region with PCR, the PCR product was digested by restriction enzyme Taq Ⅰ. The result showed that the specific bands to each species resulting in heterozygosity, which suggested this individual was a hybrid. This is the first detailed record of natural hybridization among Caesionidae species in Ryukyu Archipelago. Furthermore, we investigated 626 specimens, including adults and juveniles of these two species using the genetic marker we developed in this study. Eighteen hybrid individuals were detected in several localities (Amami-oshima Island, Ie-jima Island, Yaeyama Islands (Ishigaki-jima Island and Iriomote-jima Island), Philippines and Indonesia). Combining nuclear DNA and mtDNA data, two individuals derived from backcross were also detected. 続きを見る
10.

論文(リポジトリ)

論文(リポジトリ)
Iwamoto, Kensuke ; Abdullah, Muhamad Fadry ; Chang, Chih-Wei ; Yoshino, Tetsuo ; Imai, Hideyuki
出版情報: Biogeography : international journal of biogeography, phylogeny, taxonomy, ecology, biodiversity, evolution, and conservation biology.  17  pp.61-85,  2015-09-20.  The Biogeographical Society of Japan — 日本生物地理学会
URL: http://hdl.handle.net/20.500.12000/37547
概要: A nucleotide sequence analysis of the mitochondrial DNA control region was conducted to reveal the genetic population structure and demographic history of the mottled spinefoot Siganus fuscescens (Houttuyn, 1782), and we discussed the taxonomic treatment of S. fuscescens and white-spotted spinefoot S. canaliculatus (Park, 1797) in terms of population genetics and morphological studies. Sequence analysis indicated that the haplotypes could be clearly divided into three lineages. Morphological analysis indicated no significant differences among measurements for the three genetically divergent lineages. We concluded that each lineage had once been isolated, and then former allopatric lineages may have resulted in the sympatric distribution of lineages due to secondary contact. Siganus fuscescens regards as valid species, and S. canaliculatus is a junior synonym of S. fuscescens. 続きを見る