Ecological perspectives on the organization of biodiversity in Neotropical streams

Neotropical streams stand as one of the most biodiverse aquatic ecosystems in the world. The extremely high biodiversity of these ecosystems was generated and modified by several geological events, major climatic changes, and complex ecological mechanisms. Here we synthesize ecological concepts that influence the organization of Neotropical stream biodiversity. We analyze the ecological processes from three perspectives: horizontal (i.e., competition between species), vertical (i.e., trophic organization), and regional perspectives (i.e., environmental selection, stochasticity and dispersal). Our review highlights that Neotropical streams are understudied compared to other regions considering the three ecological perspectives and the human impacts on these ecosystems. The lack of studies in the horizontal perspective is prominent compared to the other perspectives. Overall, our knowledge of the biodiversity and dynamics of Neotropical streams is concentrated on the regional perspective and especially on the anthropogenic impacts on aquatic biodiversity. We identify some gaps in knowledge and conclude that the ecology of Neotropical streams is rapidly changing in the face of the current environmental crisis generated by multiple disturbances. These results indicate an urgent need for integrated ecological studies of Neotropical streams, considering their high global proportion of biodiversity and the multiple services these ecosystems support.