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)
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
3.

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
4.

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
5.

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
6.

論文(リポジトリ)

論文(リポジトリ)
山川, 矢敷 彩子 ; 今井, 秀行 ; Yamakawa, Ayako Yashiki ; Imai, Hideyuki
出版情報: 日本生物地理学会会報 = Bulletin of the Bio-geographical Society of Japan.  69  pp.143-160,  2014-12-20.  日本生物地理学会 — The Biogeographical Society of Japan
URL: http://hdl.handle.net/20.500.12000/37566
概要: Genetic diversity at 14 allozyme loci was examined for 12 local samples of Meretrix lamarckii from mainland Japan, an adjacent island (Tanegashima), and one sample of Meretrix sp1. collected from Iriomote Island. An unweighted pair group method with arithmetic mean (UPGMA) dendrogram of Nei’s D showed three geographical clusters; the Pacific Ocean, the Sea of Japan and Tanegashima. Two warm currents, the Kuroshio and Tsushima, play an important role in the differentiation of the genetic structure between the Pacific Ocean and the Sea of Japan. M. lamarckii inhabit the surf zone on exposed sandy beaches, and frequent gene flow between localities was predicted. However, the pairwise Fst results revealed genetically significant differences among Japanese M. lamarckii populations; the Tanegashima, Wakimoto (Kagoshima Pref.), Masuda (Shimane Pref.) and Chiribama (Ishikawa Pref.) populations were genetically independent. This is due to the relatively shorter planktonic larval period (5-10 days) of M. lamarckii compared to other bivalves (2-4 weeks). No significant genetic differences were observed among the Okuragahama (Miyazaki Pref.), Katakai (Kujyukurihama), Ooarai (Kashimanada), Akasaki and Nagasuga (Miyagi Pref.) populations. These results suggest that gene flow among the four northern Honshu populations was enabled by the warm Tsugaru current flowing north to south. In contrast, genetic similarities between the Okuragahama (Miyazaki Pref.) and the four northern Honshu populations was due to accumulated seedling releases (from Kashimanada to Okuragahama), and not gene flow caused by ocean currents. 続きを見る
7.

論文(リポジトリ)

論文(リポジトリ)
山川, 矢敷 彩子 ; 今井, 秀行 ; Yamakawa, Ayako Yashiki ; Imai, Hideyuki
出版情報: 日本生物地理学会会報 = Bulletin of the Bio-geographical Society of Japan.  68  pp.65-83,  2013-12-20.  日本生物地理学会 — The Biogeographical Society of Japan
URL: http://hdl.handle.net/20.500.12000/37565
概要: Allozyme analysis was conducted to find out genetic diversity and structure of important fishery resources Meretrix spp. (M. lusoria, M. petechialis and Meretrix sp.) in Japan, South Korea, China and Taiwan. Samples were collected from 26 Meretrix spp. populations from Japan (20 localities), Korea (2), China (1) and Taiwan (3) between 2004 and 2008. Twelve loci from 10 enzymes were examined, and heterozygosity (He, Ho), allelic richness (A), inbreeding coefficient (Fis), pairwise Fst and Nei’s genetic distance (D) were calculated. The Taiwanese Meretrix spp. from Tanshui and aquacultured samples were consists of native species from Taiwan, because it was genetically distinct from Japanese M. lusoria. Japanese M. lusoria showed small A, low He, detective bottleneck, and these low genetic diversity was caused by drastic population decline throughout Japan after 1960’s. As a result, the degree of genetic differentiation among Japanese local M. lusoria was low. However, Mutsu, Aomori Pref, population was genetically distanced from other Japanese populations based on pairwise Fst and genetic distance. Furthermore, in the Sea of Japan M. lusoria populations, latitudinal clines were observed in the allele frequency and in He. One way gene flow between neighboring localities may explain these latitudinal clines. On the other hand, in the Pacific M. lusoria populations, the locations of samples were geographically distant from each other; however, the degree of genetic differentiation was small. The large scale of seedling release might have influenced on genetic structure of Pacific M .lusoria populations through hybridization and translocation between local individuals and introduced individuals. 続きを見る
8.

論文(リポジトリ)

論文(リポジトリ)
アブドゥラ, ムハッマド ファドリー ; 井上, 博 ; 岩本, 健輔 ; 今井, 秀行 ; Abdullah, Muhamad Fadry ; Inoue, Hiroshi ; Iwamoto, Kensuke ; Imai, Hideyuki
出版情報: 沖縄生物学会誌.  48  pp.77-89,  2010-09-15.  沖縄生物学会
URL: http://hdl.handle.net/20.500.12000/37569
概要: The western form of the spotted-legged spiny lobster Panulirus lonipes longipes (A. Milne-Edwards,1 868),collected from Okinawajima Island,Okinawa Islands,]apan,i s reported here. This report represents the second record of the species from Japan. Based on the specimens examined in this study, we propose a new Japanese name “Nettai-iseebi" for P. longipes longipes. Random amplified polymorphic DNA(RAPD) analysis was used to examine phylogenetic relationships within and between 12 Indo-Pacific lobster species. In total,20 RAPD primers were screened for their use in identifying genetic polymorphism in Panulirus. Thirteen positive primers that gave highly reproducible RAPD profiles were selected for the analysis of the genetic relationships of Panulirus. The mean genetic similarity index (SI) among species measured by band sharing in all comparisons was 0.2673土0.0090. The highest SI value of their RAPD bands was 0.7698, while the lowest was 0.0931. Dendograms were constructed from the pair-wise comparisons among all species using pooled data from all positive primers. The similarity within first cluster of P. longipes complex deserves considerable attention. This finding, although restricted to one subspecies, appears to indicate that there is a low degree of genetic similarity between P. longipes longipes and P. longiρes bisρinosus with similarity value between 27 and 46%. Such low similarity indexes are more commonly observed between different species than within one species. Clusters generated from neighbor-joining and unweighted pair group method with arithmetic mean (UPGMA) analyses yielded trees with different topologies,indicating poor resolution within the lineage, although the clade of the P. longipes complex was clearly indicated. 続きを見る
9.

論文(リポジトリ)

論文(リポジトリ)
Imai, Hideyuki ; Chang, Jin-Hua ; 今井, 秀行
出版情報: 琉球大学21世紀COEプログラム「サンゴ礁島嶼系の生物多様性の総合解析」平成19年度成果発表会.  2008-03-01.  琉球大学21世紀COEプログラム
URL: http://hdl.handle.net/20.500.12000/4941
概要: 琉球大学21世紀COEプログラム「サンゴ礁島嶼系の生物多様性の総合解析」平成19年度成果発表会(平成20年3月1日開催) 招待講演会会場:理系複号棟102号室,ポスター発表会場:琉球大学50周年記念館1F
10.

論文(リポジトリ)

論文(リポジトリ)
矢敷, 彩子 ; 今井, 秀行 ; 山口, 正士 ; Yashiki, Ayako ; Imai, Hideyuki ; Yamaguchi, Masashi
出版情報: 琉球大学21世紀プログラム「サンゴ礁島嶼系の生物多様性の総合解析」平成18年度成果発表会.  2007-03-10.  琉球大学21世紀プログラム
URL: http://hdl.handle.net/20.500.12000/663
概要: 琉球大学21世紀プログラム「サンゴ礁島嶼系の生物多様性の総合解析」平成18年度成果発表会(平成19年3月10日開催) 招待講演会会場:琉球大学50周年記念館1F,ポスター発表会場:琉球大学大学会館3F