Department of Ecosystem Services, German Centre for Integrative Biodiversity Research (iDiv), Putschstr. 4, 04103 Leipzig, Germany.
Institute of Biodiversity, Friedrich Schiller University Jena, Dornburger Straße 159, 07743 Jena, Germany.
Proc Biol Sci. 2020 Dec 23;287(1941):20202653. doi: 10.1098/rspb.2020.2653.
According to classic theory, species' population dynamics and distributions are less influenced by species interactions under harsh climatic conditions compared to under more benign climatic conditions. In alpine and boreal ecosystems in Fennoscandia, the cyclic dynamics of rodents strongly affect many other species, including ground-nesting birds such as ptarmigan. According to the 'alternative prey hypothesis' (APH), the densities of ground-nesting birds and rodents are positively associated due to predator-prey dynamics and prey-switching. However, it remains unclear how the strength of these predator-mediated interactions change along a climatic harshness gradient in comparison with the effects of climatic variation. We built a hierarchical Bayesian model to estimate the sensitivity of ptarmigan populations to interannual variation in climate and rodent occurrence across Norway during 2007-2017. Ptarmigan abundance was positively linked with rodent occurrence, consistent with the APH. Moreover, we found that the link between ptarmigan abundance and rodent dynamics was strongest in colder regions. Our study highlights how species interactions play an important role in population dynamics of species at high latitudes and suggests that they can become even more important in the most climatically harsh regions.
根据经典理论，与较温和的气候条件相比，在恶劣的气候条件下，物种的种群动态和分布受物种相互作用的影响较小。在芬诺斯堪的亚的高山和北方森林生态系统中，啮齿动物的周期性动态强烈影响着许多其他物种，包括地面筑巢的鸟类，如雷鸟。根据“替代猎物假说”（APH），由于捕食者-猎物动态和猎物转换，地面筑巢鸟类和啮齿动物的密度呈正相关。然而，目前尚不清楚与气候变异性的影响相比，这些受捕食者介导的相互作用的强度如何沿着气候严酷度梯度发生变化。我们构建了一个分层贝叶斯模型，以估计 2007-2017 年期间挪威的气候变化和啮齿动物发生对雷鸟种群的敏感性。雷鸟的数量与啮齿动物的出现呈正相关，与 APH 一致。此外，我们发现雷鸟数量与啮齿动物动态之间的联系在较冷的地区最强。我们的研究强调了物种相互作用在高纬度物种的种群动态中所起的重要作用，并表明它们在最恶劣的气候地区可能变得更加重要。
