Data from: Intra-specific relatedness, spatial clustering and reduced demographic performance in tropical rainforest trees

Intra-specific negative density dependence promotes species coexistence by regulating population sizes. Patterns consistent with such density dependence are frequently reported in diverse tropical tree communities. Empirical evidence demonstrating whether intra-specific variation is related to these patterns, however, is lacking. The present study addresses this important knowledge gap by genotyping all individuals of a tropical tree in a long-term forest dynamics plot in tropical China. We show that related individuals are often spatially clustered, but having closely related neighbors reduces the growth performance of focal trees. We infer from the evidence, that dispersal limitation and negative density dependence are operating simultaneously to impact the spatial distributions of genotypes in a natural population. Furthermore, dispersal limitation decreases local intra-specific genetic diversity and increases negative density dependence thereby promoting niche differences and species co-existence as predicted by theory.

种内负密度制约（intra-specific negative density dependence）通过调控种群规模促进物种共存。在多样的热带树木群落中，符合该负密度制约的分布模式常被报道。然而，目前仍缺乏能够证明种内变异是否与这类模式相关的实证证据。本研究针对这一重要知识空白，对中国热带地区一处长期森林动态样地内的某一热带树种的所有个体进行基因分型。研究结果显示，亲缘关系相近的个体往往在空间上呈聚集分布，但紧邻的亲缘邻株会降低目标植株的生长表现。基于上述证据，我们推断扩散限制（dispersal limitation）与负密度制约会同时作用，影响自然种群中基因型的空间分布格局。此外，扩散限制可降低局域种内遗传多样性，并强化负密度制约效应，进而如理论所预测的那样，推动生态位分化与物种共存。