Analysis of causative factors in the geographic variation of Sika deer (Cervus nippon) in Japan.

只有一种鹿，梅花鹿（Cervus nippon），栖息在日本从亚北极针叶林（北海道）到亚热带竹林（Kerama群岛）的各种环境中。对1万多个标本的测量结果显示，体型、体重、头骨和鹿角的大小从北海道向喀喇马岛呈逐渐减少的趋势。北海道牡鹿的头盖骨长度、直角长度和体重分别为32cm、62cm和120kg，喀拉马群岛牡鹿的头盖骨长度、直角长度和体重分别为23cm、30cm和30kg。北海道的鹿比亚洲大陆上最大的北方亚种——日本鹿群略大。来自关东和近畿地区的鹿的大小似乎与中国大陆梅花鹿的五个亚种相似。九州最南端的鹿比中国西部的同类要小。日本南部梅花鹿的体型较小，表明它们的生长发生了新生期的变化。大小的差异不仅取决于气候的差异，还取决于生态条件。在金山岛和后户岛，鹿在高密度条件下表现为低质量（低性能）种群，而对马岛和种子岛的鹿在低密度条件下表现为高质量种群。雅库鹿的新生期变化被认为是由于它们的特殊行为，即它们对高山和陡峭的山区环境的适应。日本梅花鹿的变异是由于缺乏种间分离和广泛的气候变化所致。

Only one species of deer, Sika deer (Cervus nippon), inhabit various environments from subarctic coniferous forests (Hokkaido) to subtropical bamboo bush (Kerama Islands) in Japan. As the result of the measurements of over 10,000 specimens, the figures of body size, body weight, skull and antler size show the tendency to clinal decrease from Hokkaido towards the Kerama Islands. The skull length, straight antler length and body weight of Hokkaido stags were 32cm, 62cm, and 120kg respectively, and those of the Kerama Islands stags were 23cm, 30cm, and 30kg respectively.The deer of Hokkaido are slightly larger than those of the largest northern subspecies on the Asian continent, C. nippon hortulorum. The size of the deer from the Kanto and Kinki districts appears to be similiar to that of the five subspecies of Chinese continental Sika deer. The deer from the southernmost range of Kyushu are smaller than the same species in western China. The smaller size of the southern Sika deer in Japan indicates the neotenic changes of their growth.Differences in size not only on climatic differences, due to ecological conditions. On the Kinkazan and Goto Islands, the deer show a low quality (low performance) population under high density, and the deer of Tsushima Island and Tanegashima Island reveal a high quality population which has developed from low density. The neotenic changes of the Yaku deer is thought to be due to the specialized behaviour, namely their adaptation to high and steep mountainous environments. The variation of Sika deer in Japan is attributed to the absence of interspecific segregation and the wide climatic variation.