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ABSTRACT. We measured adult mandibles of Ryukyu wild pigs from Amami-Oshima, Kakeroma, Okinawa, Ishigaki and Iriomote Islands. The size cline was not statistically recognized among the populations of Nansei Islands. The Ishigaki population was significantly larger than Iriomote one in mandible length. Some measurement ratios indicated that the ramus is enlarged laterally and that the body of mandible is dorso-ventrally developed in Ishigaki and Iriomote populations. The Amami-Oshima mandibles were relatively smaller than those of Okinawa and Iriomote populations in length item of body of mandible. These results will contribute to the zoo-archaeology on the historical change of size and shape in the island populations, and to the evolutionary biology on the morphological adaptation of this animal.-KEY WORDS: geographical variation, mandible, osteometry, swine (Ryukyu wild pig).

ABSTRACT. The mandibles of the Japanese wild pigs (Sus scrofa leucomystax) from various geographical locations, which have been stored in the University of Tokyo and National Science Museum, Tokyo were examined. The mandibles from northern localities were larger in size than those from southern localities. The Oita population was significantly smaller than the Honshu populations. The Mie population was smaller than the Hyogo population in length from the angle of the mandible. In the multivariate analysis, the Kyushu populations could be obviously distinguished from the Honshu populations in the principal component charts. However, each Honshu population did not show the locality-specific distribution of the principal component plots.KEY WORDS: Japanese wild pig, mandible, osteometry, principal component analysis.J. Vet. Med. Sci. 62(8): 815-820, 2000 The wild pig in Japan has been taxonomically separated into two groups [4,5,9,14,16,17,23]: (1) the Japanese wild pig (Sus scrofa leucomystax) in Honshu, Shikoku and Kyushu Areas and (2) the Ryukyu wild pig (Sus scrofa riukiuanus) in Nansei Islands. While the latter has been osteometrically examined and described in detail [6-8, 12-14, 25, 26], the Japanese wild pig has not been clarified by morphological characteristics except for a few reports [1,10]. The geographical variation in particular remained unclear among various populations of the Japanese wild pig, although the animal is largely distributed in forests in the Japanese mainland. MATERIALS AND METHODSThe measurement items (Table 1, Fig. 1), and the methods of sex and age determination are based on previous reports [2,3,10,11]. The locality data was dependent on the biological records accompanied with each specimen (Table 2, Fig. 2). We cited generally the localities at the level of prefecture in Table 2. The specific localities detailed, however, are arranged in Fukushima, Nagano and Miyazaki populations with detailed records. We examined a total of 174 mandibles of the Age groups III, IV and V from various populations (Table 2). These specimens has been collected and stored in the Laboratory of Veterinary Anatomy, The University of Tokyo and the Department of Zoology, National Science Museum, Tokyo.The mandible measurement was carried out in 20 items with a vernier caliper to the nearest 1 mm. We have already published the measurement data of the specimens stored in the University of Tokyo in previous studies [10], and used these measurement values for the present statistical study. The mean values of length from the angle (LA) were compared by Student's t-test between localities to clarify the size tendency among various populations of the Japanese wild pig. All data measurements were applied for the principal component analysis to elucidate the size and shape variation among pop lations. The package software of the multivariate analysis (Shakai-Joho Service, Tokyo) added in Microsoft Excel 98 was used in this analysis. RESULTSThe mean value and standard error of 20 measurements are given in Table ...

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ABSTRACT. We measured adult mandibles of Ryukyu wild pig (Sus scrofa riukiuanus) from Tokunoshima Island and compared the osteometrical data with those from six Nansei Islands. The mandibles in Tokunoshima Island were larger than those from Amami-Oshima and Okinawa Islands in some measurements. We concluded that the size cline was not statistically recognized among populations. In the principal component analysis, the size cline was also denied, and the separation could be made among island populations in female. It is suggested that the populations in Tokunoshima and Okinawa Islands may be different from those in Amami-Oshima, Kakeroma, Ishigaki and Iriomote Islands in skull proportion.-KEY WORDS: mandible, osteometry, principal component analysis, Ryukyu wild swine, Tokunoshima.