Coevolution and Coexistece Mechanism of African Great Apes

本研究旨在通过对热带山地和低地(沿海和内陆)森林中大猩猩和黑猩猩的食物组成、觅食模式、群体形成和种间关系等数据的分析，阐明它们共存的机制。文中还对这类类人猿与其他热带森林动植物的协同进化过程进行了分析和思考。今年在加蓬进行了实地研究。通过样带普查，收集了小龙果保护区滨海森林的果实物候资料。我们发现黑猩猩的测距模式与沿海森林中的水果可获得性呈正相关。沿海和内陆森林水果稀缺的季节性不同，可能会影响黑猩猩的活动和分组模式。陆地草本植被的缺乏也刺激了黑猩猩广泛分散。K.Basabose被邀请到日本，我们和他一起分析了在刚果(金)Kahuzi-Biega国家公园收集的数据。结果表明，大猩猩的水果可获得性与日照时间长短呈正相关，而黑猩猩的果树可获得性与日长呈负相关。巢的分布还表明，黑猩猩避免在与大猩猩相同的食物树上筑巢。这些趋势表明，高质量食物的短缺可能会促进大猩猩和黑猩猩之间的生态位分离。我们仍在分析关于共域大猩猩和黑猩猩之间社会生物学特征差异的数据，并将在不久的将来提出关于它们的物种形成和共同进化的新视角。

This study aims to clarify the coexistence mechanism of gorillas and chimpanzees inhabiting tropical montane and lowland (coast and inland) forests sympatrically, by analyzing data on dietary composition, foraging patterns, group formation and interspecies relationships. Coevolution process of such apes with other fauna and flora of tropical forests is also analyzed and considered. This year field research was conducted in Gabon. Data on the fruit phenology were collected in the coastal forest of Petit Loango Reserve by the transect census. We found the positive correlation between chimpanzee ranging patterns and the fruit availability in the coastal forest. The different seasonality in fruit scarcity between the coastal and inland forests may influence movements and grouping patterns of chimpanzees. The lack of terrestrial herbaceous vegetation also stimulate chimpanzees to disperse in wide range. BASABOSE, K.was invited to Japan, and we analyzed data collected in the Kahuzi-Biega National Park, D.R.Congo with him.The results show a positive correlation between fruit availability and the length of day range for gorillas, while it was negative for chimpanzees. The distribution of nests also shows chimpanzee's avoidance to nest in the same food trees as gorillas. These tendencies suggest that the shortage of high quality foods may promote niche separation between gorillas and chimpanzees. We are still analysing data on differences in socioccological features between sympatric gorillas and chimpanzees and will present new perspectives on their speciation and coevolution in the near future.