Division of Biological Sciences, University of California, San Diego, La Jolla, California, United States of America.
Guangxi Key Laboratory of Plant Conservation and Restoration Ecology in Karst Terrain, Guangxi Institute of Botany, Guangxi Zhuang Autonomous Region and Chinese Academy of Sciences, Guilin.
PLoS Comput Biol. 2021 Apr 29;17(4):e1008853. doi: 10.1371/journal.pcbi.1008853. eCollection 2021 Apr.
When Darwin visited the Galapagos archipelago, he observed that, in spite of the islands' physical similarity, members of species that had dispersed to them recently were beginning to diverge from each other. He postulated that these divergences must have resulted primarily from interactions with sets of other species that had also diverged across these otherwise similar islands. By extrapolation, if Darwin is correct, such complex interactions must be driving species divergences across all ecosystems. However, many current general ecological theories that predict observed distributions of species in ecosystems do not take the details of between-species interactions into account. Here we quantify, in sixteen forest diversity plots (FDPs) worldwide, highly significant negative density-dependent (NDD) components of both conspecific and heterospecific between-tree interactions that affect the trees' distributions, growth, recruitment, and mortality. These interactions decline smoothly in significance with increasing physical distance between trees. They also tend to decline in significance with increasing phylogenetic distance between the trees, but each FDP exhibits its own unique pattern of exceptions to this overall decline. Unique patterns of between-species interactions in ecosystems, of the general type that Darwin postulated, are likely to have contributed to the exceptions. We test the power of our null-model method by using a deliberately modified data set, and show that the method easily identifies the modifications. We examine how some of the exceptions, at the Wind River (USA) FDP, reveal new details of a known allelopathic effect of one of the Wind River gymnosperm species. Finally, we explore how similar analyses can be used to investigate details of many types of interactions in these complex ecosystems, and can provide clues to the evolution of these interactions.
当达尔文访问加拉帕戈斯群岛时，他观察到，尽管这些岛屿在物理上相似，但最近分散到这些岛屿的物种成员已经开始彼此分化。他推测，这些分歧一定主要是由于与在这些相似的岛屿上也发生分歧的其他物种的相互作用所致。由此推断，如果达尔文是正确的，那么这种复杂的相互作用一定是推动所有生态系统中物种分化的原因。然而，许多目前预测生态系统中物种分布的一般生态理论并没有考虑物种之间相互作用的细节。在这里，我们在全球 16 个森林多样性样地（FDP）中量化了，对树木分布、生长、繁殖和死亡有显著影响的同种和异种种间相互作用的高度显著的负密度依赖性（NDD）成分。这些相互作用随着树木之间的物理距离的增加而显著下降。它们也随着树木之间系统发育距离的增加而趋于显著下降，但每个 FDP 都表现出自己独特的模式，即这种总体下降存在例外。生态系统中可能类似于达尔文所假设的一般类型的种间相互作用模式，很可能促成了这些例外。我们通过使用故意修改的数据来测试我们的零模型方法的能力，并表明该方法很容易识别修改。我们研究了在怀德河（美国）FDP 中的一些例外情况，如何揭示了一种已知的怀德河裸子植物种的化感作用的新细节。最后，我们探索了如何使用类似的分析来研究这些复杂生态系统中许多类型相互作用的细节，并为这些相互作用的进化提供线索。
