Data from: Translocation strategies for multiple species depend on interspecific interaction type

Conservation translocations – anthropogenic movements of species to prevent their extinction – have increased substantially over the last few decades. Although multiple species are frequently moved to the same location, current translocation guidelines consider species in isolation. This practice ignores important interspecific interactions, and thereby risks translocation failure. We model three different two-species systems to illustrate the inherent complexity of multi-species translocations, and to assess the influence of different interaction types (consumer-resource, mutualism, and competition) on translocation strategies. We focus on how these different interaction types influence the optimal founder population sizes for successful translocations, and the order in which the species are moved (simultaneous or sequential). Further, we assess the effect of interaction strength in simultaneous translocations, and the time delay between translocations when moving two species sequentially. Our results show that translocation decisions need to reflect the type of interaction. While all translocations of interacting species require a minimum founder population size, which is demarked by an “extinction boundary”, consumer-resource translocations also have a maximum founder population limit. Above the minimum founder size, increasing the number of translocated individuals leads to a substantial increase in the extinction boundary of competitors and consumers, but not of mutualists. Competitive and consumer-resource systems benefit from sequential translocations; but the order of translocations does not change the outcomes for mutualistic interaction partners noticeably. Interspecific interactions are important processes that shape population dynamics, and should therefore be incorporated into the quantitative planning of multispecies translocations. Our findings apply whenever interacting species are moved, for example, in reintroductions, conservation introductions, biological control or ecosystem restoration.

保护型物种迁地（conservation translocation）——即为防止物种灭绝而开展的人为物种迁移活动——在过去数十年间已大幅增长。尽管常有多个物种被一同迁移至同一区域，但当前的保护型物种迁地指南仍仅单独考量单一物种。该做法忽略了关键的种间相互作用（interspecific interaction），进而会提升迁地保护项目失败的风险。我们构建了三种不同的双物种种群模型，用以阐明多物种种群迁地保护的内在复杂性，并评估不同类型种间相互作用——包括消费者-资源（consumer-resource）关系、互利共生（mutualism）关系与种间竞争（competition）关系——对迁地保护策略的影响。本研究重点关注上述不同种间相互作用类型，如何影响成功迁地保护所需的最优奠基者种群（founder population）规模，以及物种的迁移次序（同步迁移或先后迁移）。此外，我们还评估了同步迁移情境下的相互作用强度，以及双物种先后迁移时的迁移间隔时长对项目结果的影响。研究结果表明，迁地保护的决策需匹配对应的种间相互作用类型。尽管所有涉及相互作用物种的迁地保护项目，都需要达到最低奠基者种群规模（该阈值以「灭绝边界（extinction boundary）」为界标），但消费者-资源关系的迁地保护项目还存在最大奠基者种群上限。在超过最低奠基者种群规模后，增加迁移个体数量会显著提升种间竞争与消费者-资源关系情境下的灭绝边界，但对互利共生关系的物种则无此效果。种间竞争与消费者-资源关系的种群系统，采用先后迁移策略更具优势；但迁移次序对互利共生伙伴的种群结局无显著影响。种间相互作用是塑造种群动态的关键过程，因此应将其纳入多物种种群迁地保护的量化规划框架中。本研究结论适用于所有涉及相互作用物种的迁移活动，例如物种再引入、保护引种、生物防治或生态系统修复等场景。