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Conserving freshwater habitats and their biodiversity in the Amazon Basin is a growing challenge in the face of rapid anthropogenic changes. We used the most comprehensive fish-occurrence database available (2355 valid species; 21,248 sampling points) and 3 ecological criteria (irreplaceability, representativeness, and vulnerability) to identify biodiversity hotspots based on 6 conservation templates (3 proactive, 1 reactive, 1 representative, and 1 balanced) to provide a set of alternative planning solutions for freshwater fish protection in the Amazon Basin. We identified empirically for each template the 17% of sub-basins that should be conserved and performed a prioritization analysis by identifying current and future (2050) threats (i.e., degree of deforestation and habitat fragmentation by dams). Two of our 3 proactive templates had around 65% of their surface covered by protected areas; high levels of irreplaceability (60% of endemics) and representativeness (71% of the Amazonian fish fauna); and low current and future vulnerability. These 2 templates, then, seemed more robust for conservation prioritization. The future of the selected sub-basins in these 2 proactive templates is not immediately threatened by human activities, and these sub-basins host the largest part of Amazonian biodiversity. They could easily be conserved if no additional threats occur between now and 2050., (© 2020 Society for Conservation Biology.)

Because both descriptions of species and modern human-driven extinctions started around the same time (i.e., eighteenth century), a logical expectation is that a large proportion of species may have gone extinct without ever having been recorded. Despite this evident and widely recognized assumption, the loss of undescribed species has never been estimated. We quantified this loss for several taxonomic groups and regions for which undescribed species extinctions are likely to have occurred. Across a wide range of taxonomic groups, we applied known extinction rates computed from recorded species losses to assumed exponential decay in the proportion of species remaining undiscovered. Because all previous modeling attempts to project total species richness implicitly assumed that undescribed species extinctions could be neglected, we also evaluated the effect of neglecting them. Finally, because we assumed constant description and extinction probabilities, we applied our model to simulated data that did not conform to this assumption. Actual species losses were severely underestimated by considering only known species extinctions. According to our estimates, the proportion of undiscovered extinct species over all extinctions ranged from 0.15 to 0.59, depending on the taxonomic group and the region considered. This means that recent extinctions may be up to twice as large as the number recorded. When species differed in their extinction or description probabilities, our model underestimated extinctions of undescribed species by up to 20%., (© 2014 Society for Conservation Biology.)