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世界最寒冷地に生息するサル類 : 上高地のニホンザル群で進化した水生昆虫や魚類の捕食行動
東城, 幸治;竹中, 將起
Permalink : http://hdl.handle.net/2115/89093
JaLCDOI : 10.14943/lowtemsci.81.199
KEYWORDS : ニホンザル;越冬戦略;食性;魚食;DNA メタバーコーディング;Japanese macaque;wintering;diet;fishing;DNA metabarcoding
Abstract
サル類は熱帯や亜熱帯を中心に分布し，下北半島のニホンザル集団が「北限のサル」である．気温的には中部山岳域（上高地・志賀高原など）が世界最寒の生息域で，上高地には4群約200頭のニホンザルが生息する．このうち3群に属する複数個体が，厳冬季に水生昆虫類やイワナ類を捕食していることが究明された．サル類一般に，水を苦手とすることから，世界的な「サル類の行動・生態学」の観点からは驚愕的な行動といえる．本稿では，メディアとの連携により撮影された動画の分析から，餌資源の乏しい厳冬季に，水温の高い湧水を含む緩流条件下で，まず水草食が進化し，次いで水生昆虫食を介して魚食行動が進化したとするシナリオを提唱する．
Monkeys, which are mainly distributed in the tropics and subtropics, do not prefer cold environments, and Japanese macaques inhabiting the Shimokita Peninsula in the Japanese Archipelago are considered to be at the "Northern limit of monkeys". Monkeys inhabiting the alpine and sub-alpine zones of the central mountainous region of Japan, where the temperature is lower than that of the Shimokita Peninsula, are considered to be inhabiting the coldest environments for primates in the world, the Kamikochi area being such location. About 200 Japanese macaques inhabit the Kamikochi area, and consisting of four troupes currently. Among them, it was found that at least some individuals belonging to three of the troupes prey on aquatic insects and char fish during the severe winter. Since it is also well known that monkeys generally dislike water, this is a startling behavior from the viewpoint of the global "ethology and ecology of monkeys". Herein, we review the process leading up to clarifying the fishing behavior of Japanese macaques in the Kamikochi area, and the results of analyzing video images obtained by introducing a large number of automatic filming systems in cooperation with a major professional media organization. In addition, we propose a scenario whereby during severe winters when food resources are scarce under relatively mild water conditions due to moderate temperature water flows from underground springs, herbivorous behavior evolved first, and subsequently evolved to diet for aquatic insects, and further adapting the fishing.
Monkeys, which are mainly distributed in the tropics and subtropics, do not prefer cold environments, and Japanese macaques inhabiting the Shimokita Peninsula in the Japanese Archipelago are considered to be at the "Northern limit of monkeys". Monkeys inhabiting the alpine and sub-alpine zones of the central mountainous region of Japan, where the temperature is lower than that of the Shimokita Peninsula, are considered to be inhabiting the coldest environments for primates in the world, the Kamikochi area being such location. About 200 Japanese macaques inhabit the Kamikochi area, and consisting of four troupes currently. Among them, it was found that at least some individuals belonging to three of the troupes prey on aquatic insects and char fish during the severe winter. Since it is also well known that monkeys generally dislike water, this is a startling behavior from the viewpoint of the global "ethology and ecology of monkeys". Herein, we review the process leading up to clarifying the fishing behavior of Japanese macaques in the Kamikochi area, and the results of analyzing video images obtained by introducing a large number of automatic filming systems in cooperation with a major professional media organization. In addition, we propose a scenario whereby during severe winters when food resources are scarce under relatively mild water conditions due to moderate temperature water flows from underground springs, herbivorous behavior evolved first, and subsequently evolved to diet for aquatic insects, and further adapting the fishing.
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