Data from: Specialized mutualisms may constrain the geographical distribution of flowering plants

It is commonly assumed that the geographical distributions of plants are governed mainly by abiotic variables. However, interactions with other organisms, such as pollinators, also have the potential to influence plant distributions. To investigate this, we developed niche models for 32 plant taxa that have specialized pollination systems and which are native to a biodiversity hotspot (South Africa). We found that the distributions of these taxa are best explained by a combination of biotic (pollinators) and abiotic factors, rather than by abiotic factors alone. For ~66% of these plant taxa, pollinator distributions were the factor that provided the best predictor of their niches. Furthermore, co-occurrence of these plants and their pollinators, was generally not explained solely by shared abiotic niches, and thus likely reflects broad-scale positive ecological interactions. These results are consistent with the proposal that pollinator distributions may constrain plant distributions and highlight the general potential for species distributions to be shaped by positive interactions with other species. This has important consequences for predicting how distributions of species might change in the face of loss of their key mutualists.

学界普遍认为植物的地理分布主要受非生物变量调控。然而，与传粉者等其他生物的种间相互作用，同样可能影响植物的分布格局。为探究这一科学问题，我们针对32个具有特化传粉系统、且原产于南非这一生物多样性热点（biodiversity hotspot）区域的植物类群，构建了生态位模型（niche models）。研究结果显示，相较于仅以非生物因子进行解释，结合生物因子（传粉者）与非生物因子的模型，能更精准地阐释这些植物类群的分布格局。其中约66%的植物类群，其生态位的最佳预测因子为传粉者的分布。此外，这些植物与其传粉者的共现关系，通常无法仅通过共享的非生物生态位来解释，因此其共现大概率反映了大尺度下的正向生态相互作用。本研究结果与“传粉者分布可能限制植物分布”的假说相符，同时凸显了物种间正向相互作用在塑造物种分布格局方面的普遍潜力。该结论对于预测关键互利共生伙伴丧失后，物种分布可能发生的变化具有重要的理论与实践价值。