Freshwater vertebrate and invertebrate diversity patterns in an Andean-Amazon basin: implications for conservation efforts

The basin has conspicuous information gaps on its biodiversity patterns and human threats. To address this, researchers estimated the diversity distribution patterns of freshwater vertebrates and invertebrates in the Napo Basin, as a tool for present and future management and conservation efforts. The study compiled occurrence records for 481 freshwater vertebrate species (amphibians, birds, mammals, reptiles, and fish), and 54 invertebrate families obtained across an altitudinal gradient of the basin (200-4500 m). Using these occurrence records and environmental variables, the researchers modeled the distribution of each vertebrate species and invertebrate family. Then, they stacked these distributions to build species richness maps for vertebrates, and a family richness map for invertebrates. The results showed that the most diverse areas for vertebrate species are the lowlands (<600 m), whereas richness of invertebrate families peaks at higher elevations (lower montane forests). Congruence among species richness patterns of the five vertebrate groups was high (r = 0.66), with fish being the best predictor for vertebrates (r = 0.78). However, congruence decreased at higher elevations (r = 0.14), suggesting that specific species or habitat-based approaches should be used in the highlands. A high correlation was found between species and family richness of freshwater invertebrates (r = 0.66), suggesting that family richness of invertebrates could be used as a surrogate of species richness in this basin. This correlation is particularly useful at the watershed scale, where species-level taxonomy is challenging. The study highlights the need for incorporating different taxonomic groups when assessing diversity patterns, and recommends that conservation programs for this basin should incorporate both vertebrate and invertebrate groups as biodiversity indicators. The study provides a practical methodological guidance in the estimation of freshwater diversity in regions of scarce information with high conservation priority, such as the Andean-Amazon basins. The results provide the first comprehensive representation of freshwater biodiversity patterns at high resolution in an Andean-Amazon basin, and emphasize the importance of considering different taxonomic groups when evaluating diversity patterns.