Diversity and distribution of Ephemeroptera (Insecta) along the Colombian Andean-Amazonian transition

The Andean-Amazon region harbors exceptional biodiversity; however, aquatic diversity in its transitional zones remains understudied. Here, we evaluated the alpha and beta diversities of mayflies across the Andean-Amazonian transition in Caquet & aacute;, Colombia, to assess how environmental gradients influence their distribution. We sampled mayflies and characterized the environmental features in the rivers of the Andes, Transition, and Amazonia regions during four field expeditions. We estimated the Hill number, performed principal coordinate analysis, and applied PERMANOVA to identify differences in taxonomic composition across the three regions. We also used Indval to identify indicator taxa, estimated beta diversity components, local contribution to beta diversity, and species contribution to beta diversity. Redundancy analysis helped to identify environmental variables predictive of assemblage composition and beta diversity. Our results showed distinct diversity patterns of Ephemeroptera among the regions, with species replacement as a key beta diversity component, and identified 14 indicator taxa. Significant environmental variables included substrate, land use for forest conservation, and vegetation cover dominated by pasture. The analysis of local and species contributions to beta diversity highlighted key stations and species for conservation efforts. This study enhances the understanding of Ephemeroptera distribution and diversity in the Andean-Amazon region, providing valuable insights for future conservation.