Data from: An overlooked plant-parakeet mutualism counteracts human overharvesting on an endangered tree

The exponential growth of the human population often causes the overexploitation of resources and disruption of ecological interactions. Here we propose that the antagonist effect of humans on exploited species might be alleviated with the advent of a second predator species. We focused on the complex interactions between an endangered conifer (Araucaria araucana) and two seed exploiters: the Austral parakeet (Enicognathus ferrugineus) and human seed collectors. We tested the importance of partial seed consumption by parakeets as an escape to human seed harvesting. Although parakeets frequently ate whole seeds, a substantial proportion of the seeds found under trees were only partially eaten and avoided by human collectors. These seeds germinated at a similar proportion but faster than intact seeds under laboratory conditions. Our results revealed an overlooked mutualism between parakeets and an endangered tree. Incomplete seed eating by parakeets, plus selection against these eaten seeds by humans may enhance regeneration possibilities for this conifer species subject to human seed collection, turning the scale of the antagonism-mutualism continuum to the mutualistic side. In this context, parakeets might be providing an important service in those forests subject to human harvesting by allowing a fraction of seeds to escape human predation.人口指数级增长往往会造成资源过度开发与生态互动破坏。在此我们提出，当第二种捕食者物种出现时，人类对被取食物种的拮抗效应或可得到缓解。本研究聚焦于一种濒危针叶树——智利南洋杉（Araucaria araucana）与两类种子取食者之间的复杂互动：澳长尾鹦鹉（Enicognathus ferrugineus）以及人类种子采集者。我们验证了长尾鹦鹉的部分取食行为是否可作为种子逃避人类采收的有效途径。尽管长尾鹦鹉常会取食完整种子，但树下发现的大量种子仅被部分取食，且未被人类采集者所青睐。实验室条件下，这类部分被取食的种子萌发率与完整种子相近，但萌发速度更快。本研究结果揭示了长尾鹦鹉与濒危针叶树之间此前被忽视的互利共生关系。长尾鹦鹉的不完全取食行为，加之人类对被取食种子的选择偏好，或可提升受人类种子采收影响的该针叶树种的种群更新潜力，使拮抗-互利连续谱向互利方向倾斜。在此背景下，在受人类采收活动影响的森林中，长尾鹦鹉通过让部分种子逃脱人类捕食，或许提供了一项重要的生态服务。