著者

竹元 博幸

出版者

一般社団法人 日本霊長類学会

雑誌

霊長類研究 (ISSN:09124047)

巻号頁・発行日

vol.34, no.1, pp.87-102, 2018 (Released:2018-08-22)

参考文献数

75

被引用文献数

1

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The origin of bonobos and the history of their dispersion in the southern Congo Basin were investigated from the perspectives of biogeography and the paleo-environment. Why bonobos are distributed in the southern Congo Basin was unclear because of limited geological records about the region and genetic information for bonobos. Recently, colleagues and I proposed some hypotheses concerning the history of bonobos based on recent reports about marine sediments and structural geology of the Congo basin, as well as new mitochondrial DNA haplotypes collected from seven wild bonobo populations. Here, I illustrate these hypotheses, namely: 1) the Congo River functioned as a biogeographical barrier for forest animals since 34 million years ago; 2) the ancestor of present bonobo populations crossed the upper parts of the Congo River from the right bank to the left bank during the early Quaternary period; and, 3) factors affecting the genetic structure of present bonobos. Lastly, I propose possible future studies to investigate bonobo evolution.

著者

山越 言 竹元 博幸 松沢 哲郎 杉山 幸丸

出版者

Primate Society of Japan

雑誌

霊長類研究 (ISSN:09124047)

巻号頁・発行日

vol.15, no.2, pp.101-114, 1999 (Released:2009-09-07)

参考文献数

169

被引用文献数

4 4

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This review summarizes the findings from 40 years of research on a chimpanzee group at Bossou, Guinea, conducted mainly by two research teams, one from the University of Amsterdam, Netherlands, and the other from Kyoto University, Japan, and reports the current conservation status of the chimpanzee group.Research in the 1960's by the Dutch team consisted of short-term, ‘testing-a-hypothesis’ type projects, which focused on the chimpanzees' agonistic behavior towards predators. They used a unique field-experiment method, with an artificial leopard, to see how the chimpanzees responded to the stimulus. The experiments revealed a variety of agonistic reactions by chimpanzees, including tool-using behavior such as throwing a branch and using a stick as a club.In 1976, the Japanese team launched a long-term project, based on recognizing each chimpanzee individually. Although diverse topics have been covered to date, a focus has been tool use. Starting with the first substantial direct observation of nut cracking by wild chimpanzees, many other types of tool use have since been described, including ant dipping, pestle pounding, and algae scooping. A series of field experiments followed that revealed many details about nut cracking by chimpanzees: hand preference, metatool, developmental process, etc. Feeding ecology is a more recent topic, and the utilization of oil palm as a ‘keystone resource' when fruit is scarce, using two types of tool, proved to have significant ecological importance. Unique social characteristics like male immigration, close between-female relationships, and females’ high reproductive performances have been brought to light and require more ecological and genetic study to understand their uniqueness comprehensively.As for the conservation status of Bossou chimpanzees, the population size has fluctuated, but has been essentially stable during the study period. The reproductive parameters appear good, but juveniles of both sexes tend to disappear for unknown reasons. The people of Bossou have a strong religious motivation for conserving small patches of forest and the chimpanzees living there, and there is good collaboration among the Bossou people, government institutions and researchers when dealing with conservation problems. Current concerns seem to be the genetic isolation from a neighboring chimpanzee population on Mt. Nimba, and crop damage caused by the chimpanzees.

著者

竹元 博幸

出版者

京都大学

雑誌

挑戦的萌芽研究

巻号頁・発行日

2007

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Takemoto(2004)は、チンパンジーの地上利用頻度に季節差があるのは、樹上果実量が多いときに樹上を良く利用するためではなく、気温が高い季節は地上部が過ごしやすい気温になるためだと結論している。熱帯林内の林冠付近は地上部にくらべ気温が高いのが一般的傾向であると言われているが、アフリカの大型類人猿調査地で気温の垂直構造が測定された事はない。本研究は、熱帯林内の食物量と気温や湿度など物理環境の変動を地上部から林冠までの垂直構造とともにとらえ、野生チンパンジーとボノボの森林内空間利用がどのように変化するかを明らかにすることである。本年度は今まで収集した資料を用いて両種の生息地の環境と地上利用の違いを解析した。西アフリカ・ボッソウのチンパンジーの地上利用時間は乾季に増大し、雨期に減少する。また、雨期には林冠に近い高さを良く利用するが、乾季の利用高度は低くなる。対して中央アフリカ・ワンバ地域のボノボの地上利用時間の季節差は無く、森林内の利用高度も変化しなかった。両生息地とも林冠付近の気温は5℃程度地上付近の気温より高かったが、気温の季節変化はボッソウが大きい。多変量解析によると、地上性の差は種や調査地あるいは果実量の差ではなく、観察日の気温の影響が強いことが判明した。森林内気温の季節変化が大きいボッソウ地域に対して季節差の少なかったワンバ地域の気象が森林内利用空間の違いをもたらしていると考えられる。今後2種の採食内容を比較するとともに、アフリカ古気候の変遷が2種の生態に与えた影響について考察したい。