Coevolution and Coexistece Mechanism of African Great Apes

本研究旨在通过分析热带山地和低地（沿海和内陆）森林大猩猩和黑猩猩的饮食组成、觅食方式、群体形成和种间关系等数据，阐明它们的共存机制。本文还分析和考虑了这些类人猿与热带森林其他动植物群的共同进化过程。今年在加蓬进行了实地调查。采用样带调查方法，收集了小罗安戈保护区沿海森林的果实物候资料。我们发现黑猩猩的分布模式与沿海森林的水果可得性呈正相关。沿海和内陆森林水果稀缺的季节性差异可能会影响黑猩猩的运动和群体模式。陆地草本植物的缺乏也促使黑猩猩在更大范围内分散。BASABOSE被邀请到日本，我们和他一起分析了在刚果民主共和国Kahuzi-Biega国家公园收集的数据。结果显示，大猩猩的水果可得性与白昼长度呈正相关，而黑猩猩则为负相关。巢穴的分布也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。我们仍在分析同域大猩猩和黑猩猩之间社会生态特征差异的数据，并将在不久的将来对它们的物种形成和共同进化提出新的观点。

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.