Diversity of amphibians and squamate reptiles in the upper Napo River basin, Ecuador

The upper Napo River basin, located in one of the world’s most biodiverse regions, the Tropical Andes in the Western Amazon, exhibits high ecosystem heterogeneity, from lowlands to high páramo grasslands, making it an ideal model for studying biodiversity patterns. We studied amphibian and reptile community composition across five localities in the basin, covering a wide elevational range. Surveys were conducted in 2018 and 2019, estimating α, β, and γ-diversity, accumulation, rarefaction, and extrapolation curves, as well as Species Abundance Distribution (SAD) patterns. To analyze diversity indexes, we used effective numbers of species (Hill numbers). We recorded 688 amphibians (131 species) and 180 reptiles (52 species). Curaray had the highest species richness, while Narupa had the lowest. Significant differences in species diversity and composition (β-diversity) were found among several locality pairs, particularly between Curaray and other sites. For amphibians, differences were driven by both turnover and richness; for reptiles, richness differences were more influential. Rarefaction and extrapolation confirmed Curaray as the most diverse site, though Narupa and Llanganates showed higher sample completeness. Evenness indices (Pielou, Simpson, Smith & Wilson) indicated relatively equitable species distribution, though Simpson’s index revealed slightly lower evenness across sites. Between 13.7% and 18.3% of amphibian species and 3.8% to 13.4% of reptile species are threatened, with La Bonita Reserve hosting the highest number of threatened species. There is no hyper-dominance of amphibians, aligning with each locality’s conservation status. Our results highlight this basin as a highly diverse and endemic area with great potential for further exploration and research.