Doctoral Dissertation Research: Effects of a Dispersal Barrier on Cultural Similarity in Wild Orangutans (Pongo pygmaeus wurmbii)

这个项目将对我们不断增长的类人猿行为生态学和遗传学知识做出广泛贡献，同时通过对传播屏障两侧文化行为的调查，进一步研究人类起源。对猩猩任意信号变化和基本符号使用的识别表明，之前的研究可能只是触及了这一谱系中现有文化差异的表面，这一现象本身对人类来说很有趣，因此能够产生对猩猩保护的重大兴趣。因为动物不能跨越传播边界，文化变异应该反映从创新地点到被传播屏障阻挡的传播历史。该项目将测试文化解释的能力，以解释野生婆罗洲猩猩（Pongo pygmaeus wurmbii）在加里曼丹中部一条150米宽的河流两侧所表现出的行为变化模式，这条河流目前是猩猩在研究区域扩散的有效屏障，但在其更狭窄的源头提供了基因流动的机会。在保持生态变异和遗传相关性不变的情况下，对河流屏障两侧的猩猩进行同步研究，提供了一个特殊的机会，可以从经验上评估行为变异的文化解释假设（基于社会学习的机会）。该项目将评估社会学习对猩猩生存和当地适应所需技能的影响，这对目前正在进行的重新引入工作的成功至关重要。它还将使我们更好地了解生态和社会背景，这些环境有利于猩猩在特定情况下的文化解决方案，而不是在其他情况下，这将使我们深入了解类人猿最后的共同祖先的文化可能程度。更广泛地说，该项目将通过记录野生猩猩行为的地理差异在多大程度上通过社会传播得以维持，以及重新引入或迁移的动物在多大程度上难以完全适应当地条件，从而帮助保护倡议。这项研究将为促进学生的训练和参与研究提供许多机会。初步数据是在杜克大学的一名本科生以及几名印尼当地助理和大学生的帮助下收集的。拟议的研究将继续为印度尼西亚的学生和助理提供培训，并将促进与印度尼西亚、欧洲和美国同行的国际合作。目前，猩猩只生活在婆罗洲和苏门答腊岛的小片森林中。尽管受到正式的保护，但猩猩已经成为一种极度濒危的物种，由于木材开采的持续威胁和人类对其活动范围的侵占，预计在未来20年内会灭绝。这项研究必须尽快进行，因为随着栖息地的持续破坏，具有独特地方传统的单个猩猩种群将会消失，从而失去记录野生猩猩文化行为的全部机会。

This project will contribute broadly to our growing knowledge of great ape behavioral ecology and genetics, while furthering the study of human origins through an investigation of cultural behavior on two sides of a dispersal barrier. The identification of arbitrary signal variation and rudimentary symbol use in orangutans suggests that previous studies may only have scratched the surface of existing cultural variation in this lineage, a phenomenon that is inherently interesting to humans and therefore capable of generating significant interest in orangutan conservation. Because animals cannot cross dispersal boundaries, cultural variants should reflect the history of diffusion from the locations(s) of innovation until blocked by a dispersal barrier. This project will test the ability of a cultural interpretation to account for patterns of behavioral variation exhibited by wild Bornean orangutans (Pongo pygmaeus wurmbii) ranging on either side of a 150m-wide river in Central Kalimantan, which currently serves as an effective barrier for orangutan dispersal in the study region, but offers opportunities for gene flow at its more narrow headwaters. The synchronized study of orangutans on opposite sides of a river barrier offers an exceptional opportunity to empirically evaluate the assumptions of a cultural interpretation for behavioral variation (based on opportunities for social learning), while holding both ecological variation and genetic relatedness constant. This project will assess the impact of social learning on the presence of skills required for orangutan survival and local adaptation, which are critical to the success of reintroduction efforts currently underway. It will also give us a greater understanding of the ecological and social contexts that favor cultural solutions for orangutans in particular situations but not in others, which will give us insight into the likely extent of culture in the last common ancestor of the great apes. More broadly, this project will aid conservation initiatives by documenting the extent to which geographic variation in wild orangutan behavior is maintained by social transmission and, therefore, the extent to which reintroduced or translocated animals have difficulty achieving full adaptation to local conditions. This research will provide numerous opportunities for promoting student training and participation in research. Preliminary data were collected with the help of a Duke University undergraduate student as well as several local Indonesian assistants and university students. The proposed research will continue to provide training for Indonesian students and assistants and will promote international collaboration with Indonesian, European, and American counterparts. The orangutan is presently confined to highly fragmented populations in small forest patches on the islands of Borneo and Sumatra. Despite its formally protected status, the orangutan has become a critically endangered species, the extinction of which is anticipated within the next two decades due to the continuing threat of timber exploitation and human encroachment throughout its range. It is critical that this research be carried out soon, because there is a danger that as habitat devastation continues, individual orangutan populations with unique local traditions will vanish, resulting in lost opportunities to document the full extent of cultural behavior in wild orangutans.