Forest inventories in Amazonia include around 5000 described tree species belonging to more than 800 genera. Numerous species-rich genera share genetic variation among species because of recent speciation and/or recurrent hybridisation, forming species complexes. Despite the key role that tree species complexes play in understanding Neotropical diversification, and their need to exploit a diversity of niches, little is known about the mechanisms that allow local coexistence of tree species complexes and their species in sympatry. In this study, we explored the fine-scale distribution of five tree species complexes and 22 species within these complexes. Combining forest inventories, botanical determination, and LiDAR-derived topographic data over 120 ha of permanent plots in French Guiana, we used a Bayesian modelling framework to test the role of fine-scale topographic wetness and tree neighbourhood on the occurrence of species complexes and the relative distribution of species within complexes. Species complexes of Neotropical trees were widely spread across the topographic wetness gradient at the local scale. Species within complexes showed pervasive niche differentiation along with topographic wetness and competition gradients. Similar patterns of species-specific habitat preferences were observed within several species complexes: species more tolerant to competition for resources grow in drier and less fertile plateaus and slopes. If supported by partial reproductive isolation of species and adaptive introgression at the species complex level, our results suggest that both species-specific habitat specialisation within species complexes and the broad ecological distribution of species complexes might explain the success of these species complexes at the regional scale.

亚马逊地区的森林清单包括约5000种描述的树种，属于800多个属。由于最近的物种形成和/或反复杂交，形成物种复合体的物种丰富，许多物种在物种之间共享遗传变异。尽管树种复合体在理解新热带多样性方面起着关键作用，并且需要利用各种生态位，但对于允许树种复合体及其物种在共生系统中局部共存的机制知之甚少。在这项研究中，我们探索了5种树种复合物和这些复合物中22种的精细分布。结合法属圭亚那120公顷永久性土地上的森林清单，植物确定性和LiDAR得出的地形数据，我们使用贝叶斯建模框架来测试精细尺度的地形湿度和树木邻域对物种复合物的发生以及物种在复合物中的相对分布的作用。新热带树木的物种复合体广泛分布在局部尺度的地形湿度梯度上。复合物中的物种显示出普遍的生态位分化以及地形湿度和竞争梯度。在几个物种复合体中观察到相似的物种特异性生境偏好模式：在干旱地区和肥沃的高原和山坡上，对资源竞争更具耐受性的物种。如果得到物种的部分生殖隔离和物种复杂水平的适应性渗入的支持，