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.

人口的指数级增长常引发资源过度开发与生态互作的破坏。本研究提出，随着第二种捕食者物种的出现，人类对被开发物种的拮抗效应或可得到缓解。我们聚焦于一种濒危针叶树——智利南洋杉（Araucaria araucana）与两种种子取食者：澳长尾鹦鹉（Enicognathus ferrugineus）及人类种子采集者之间的复杂互作关系。我们验证了鹦鹉对种子的部分取食作为人类种子采集逃逸策略的重要性。尽管鹦鹉常取食完整种子，但树下发现的大量种子仅被部分取食，且未被人类采集者取用。在实验室条件下，这类种子的萌发率与完整种子相近，但萌发速度更快。本研究结果揭示了鹦鹉与濒危针叶树之间一种此前被忽视的互利共生关系。鹦鹉对种子的不完全取食，加之人类对这类被取食种子的规避选择，或可提升受人类种子采集影响的该针叶树物种的更新潜力，使拮抗-互利连续谱的天平向互利一侧倾斜。在此背景下，鹦鹉通过使部分种子逃脱人类的取食，可为受人类采集活动影响的森林提供一项重要的生态服务。