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1 0 0 0 OA <国立科博専報>琉球列島の自然史科学的総合研究 : 実施の趣旨と昭和47年度の調査成績の概要

著者: 今泉吉典
出版者: 国立科学博物館
雑誌: 国立科学博物館専報 (ISSN:00824755)
巻号頁・発行日: vol.6, pp.1-8, 1973

2020-10-16 06:07:04
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https://ci.nii.ac.jp/naid/110004313225

1 0 0 0 OA <国立科博専報>対馬(および壱岐)とその周辺地域の自然史科学的総合研究の成果の要約

著者: 今泉吉典
出版者: 国立科学博物館
雑誌: 国立科学博物館専報 (ISSN:00824755)
巻号頁・発行日: vol.3, pp.381-395, 1970

2020-10-16 06:07:04
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https://ci.nii.ac.jp/naid/110004313187

1 0 0 0 OA <国立科博専報>日高の陸棲哺乳類 : とくに固有のヤチネズミ類とその起源について

著者: 今泉吉典
出版者: 国立科学博物館
雑誌: 国立科学博物館専報 (ISSN:00824755)
巻号頁・発行日: vol.5, pp.131-149, 1972
被引用文献数: 8

According to the investigation executed by the party from the National Science Museum, Tokyo, in the summers of 1970 and 1971,the small mammal fauna of the Hidaka Mountains, Hokkaido, is fairly different from most of the plains but rather similar to that of Rishiri Island, a small island off the northern extremity of the main island, in the combination of important species. They resemble each other not only in the presence of a vole of the Clethrionomys rex group and a tiny shrew nearly related to Sorex gracillimus THOMAS, 1907,but also in the absence of Sorex shinto saevus THOMAS, 1907,one of the two common shrews in the plains of the main island of Hokkaido. Voles of the rex group, containing Clethrionomys rex IMAIZUMI, 1971,of Rishiri Island and C. montanus sp. nov. of the Hidaka Mountains, are evidently more primitive in several external, cranial and dental characters than those of the rufocanus group, which contains C. bedfordiae (THOMAS, 1905) of the main island of Hokkaido and C. sikotanensis (TOKUDA, 1935) of Rishiri I. and Shikotan I. of the Habomai Islands. Moreover, within the respective groups, the forms of small islands are less advanced than those of the main island as shown in Fig. 1. These nearly related forms belonging to the same clade with compete each other when they are in a sympatric condition of distribution, because they are probably poorly differentiated in the ecological niche. In such cases more advanced forms tend to destroy the primitive ones, as clearly seen in three lineages of Japanese moles, Mogera minor, M. wogura and M. kobeae (IMAIZUMI, 1964). A lineage, here used by the author, is a taxon applied not only to good species but also ill-defined hemispecies or even some of subspecies based on the biological species concept, and differs from other lineages by the relative time of emergence or of animated expansion of the distribution. Such competition may be more violent in a combination of nearest two lineages than that of rather remote ones, as the former is less different in physical characters and also in ecological niches than the latter. Evident correlations between the degree of specialization and the relative time of emergence of taxa have been confirmed among the lineages of the glareolus group, of the Japanese moles, etc. If this is acceptable as a general rule, the earliest of the four lineages of the voles that arrived in the Hokkaido district might be Clethrionomys rex, now confined to Rishiri Island (Fig.1). At first probably C. rex and then C. sikotanensis expanded their distribution nearly all over the district. Later, both of the populations were exterminated from the main island of Hokkaido through violent competitions with newly arrived and more advanced lineages, C. montanus of the former group and C. bedfordiae of the latter one. On the other hand, not so violent but rather loose competitions have been carried on between these conquerors, and montanus was gradually exterminated from the plains and finally almost confined to the alpine and subalpine zones of the Hidaka Mountains. Very similar process of emergences and competitions might be carried out between Sorex shinto saevus and a tiny shrew similar to Sorex gracillimus. The former, which has now nearly exterminated tha latter from the plains of the main island, probably failed to invade into Rishiri Island because of its later arrival. Thus, the similarities between the small mammal faunas of Rishiri Island and the high mountain zone of Hidaka Mountains can easily be understood as a result of successive appearances and expansions of slightly advanced lineages in the same clade and violent competitions between them which can be hindered by some topographical factors.

2020-10-16 06:07:04
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https://ci.nii.ac.jp/naid/110004313213

1 0 0 0 OA 琉球列島の自然史科学的総合研究 : 調査経過の概要と研究結果の要約

著者: 今泉吉典青木淳一浅沼靖土居祥兌小山博滋斎藤靖二氏家宏
出版者: 国立科学博物館
雑誌: 国立科学博物館専報 (ISSN:00824755)
巻号頁・発行日: vol.7, pp.1-18, 1974

2020-10-16 06:07:04
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https://ci.nii.ac.jp/naid/110004313656

1 0 0 0 OA <国立科博専報>琉球列島産イノシシの分類学的考察

著者: 今泉吉典
出版者: 国立科学博物館
雑誌: 国立科学博物館専報 (ISSN:00824755)
巻号頁・発行日: vol.6, pp.113-129, 1973
被引用文献数: 4

Although the wild boar of the Ryukyu Islands, Japan, has long been recognized as a local race of Sus scrofa LINNAEUS, 1758,by most of the recent authors, it may be a relict nearly related to the common ancestor of the boars. According to the author's opinion, Sus scrofa itself is a superspecies containing such distinct species as cristatus, scorofa, meridionalis, vittatus, leucomystax and riukiuanus. Each of the last three forms of East Asia undoubtedly belonging to a clade, the vittatus group, is in different stage of phylogenetic sequence and seems to have independent history of expansion of the population in the past. It is most likely that such populations have been reproductively isolated from each other more or less completely and that severe competition for existence may have taken place when they meet in a given area. The present distribution of those species must be a final result of such competitions reflecting the presence of reproductive isolation between them. This is the reason why the author is inclined to erect them as distinct species. The wild boar of the Ryukyu Islands, Sus riukiuanus KURODA, 1924,will be recognized on the following cranial and dental characters : upper length of skull as large as that in a cline of leucomystax TEMMINCK, 1942,from Honshu and Kyushu, Japan, Yc=153.8+4.9Xmm, Sys=15.9mm (X=temperature index), and much smaller than that of vittatus BOIE, 1828,Yc=302.0+2.4Xmm, Sys=19.4mm, which contains populations from Ussuri, Manchuria, Korea, Szechwan, Fukien, Formosa, Johore, Sumatra, Java, etc. Second and third upper molars smaller and simpler, and auditory bulla smaller than those of leucomystax. Naso-premaxillary suture incomplete except in old stage, and condyle and angular portion of mandible less developed. Those characters are most clearly retained in the population of Iriomote Island. The cranial and dental characters of the native domestic pig of Hainan, China, are distinctly in primitive conditions than those of vittatus and leucomystax, but evidently in progressed stage of phylogenetic development than in riukiuanus. The opinion of some authors that riukiuanus may only be a feral domestic pig seems not to be acceptable.