Red List assessment of amphibian species of Ecuador: A multidimensional approach for their conservation

Abstract

Ecuador is one of the most biodiverse countries in the world, but faces severe pressures and threats to its natural ecosystems. Numerous species have declined and require to be objectively evaluated and quantified, as a step towards the development of conservation strategies. Herein, we present an updated National Red List Assessment for amphibian species of Ecuador, with one of the most detailed and complete coverages for any Ecuadorian taxonomic group to date. Based on standardized methodologies that integrate taxonomic work, spatial analyses, and ecological niche modeling, we assessed the extinction risk and identified the main threats for all Ecuadorian native amphibians (635 species), using the IUCN Red List Categories and Criteria. Our evaluation reveals that 57% (363 species) are categorized as Threatened, 12% (78 species) as Near Threatened, 4% (26 species) as Data Deficient, and 27% (168 species) as Least Concern. Our assessment almost doubles the number of threatened species in comparison with previous evaluations. In addition to habitat loss, the expansion of the agricultural/cattle raising frontier and other anthropogenic threats (roads, human settlements, and mining/oil activities) amplify the incidence of other pressures as relevant predictors of ecological integrity. Potential synergic effects with climate change and emergent diseases (apparently responsible for the sudden declines), had particular importance amongst the threats sustained by Ecuadorian amphibians. Most threatened species are distributed in montane forests and paramo habitats of the Andes, with nearly 10% of them occurring outside the National System of Protected Areas of the Ecuadorian government. Based on our results, we recommend the following actions: (i) An increase of the National System of Protected Areas to include threatened species. (ii) Supporting the ex/in-situ conservation programs to protect species considered like Critically Endangered and Endangered. (iii) Focalizing research efforts towards the description of new species, as well as species currently categorized as Data Deficient (DD) that may turn out to be threatened. The implementation of the described actions is challenging, but urgent, given the current conservation crisis faced by amphibians.

Fig 1. Spatial distribution of records from the amphibian database.

A total of 37,328 records from 635 native species (including Rana catesbeiana, an introduced species) assessed for the IUCN Red List of Ecuadorian amphibians. Categories in the legend correspond to the National System of Protected Areas (SNAP, from Spanish acronym) in Ecuador. Details of collections, sources, and databases are provided in the S2 Table.

Fig 2. IUCN Red List of amphibians from Ecuador.

The number of species by (a) Categories and (b) Criteria. Categories: CR = Critically Endangered, EN = Endangered, VU = Vulnerable, NT = Near Threatened, LC = Least Concern, DD = Data Deficient, NE = Not Evaluated—corresponds to Rana catesbeiana, an invasive species in Ecuador. Atelopus ignescens (Critically Endangered) was believed to be extinct until its rediscovery in 2016. Illustration by PARG.

Fig 3. A taxonomic perspective of the Red List status of amphibians in Ecuador.

The species composition (% of threatened species) of each family in Anura (dark blue), Caudata (bright blue), and Gymnophiona (purple) is characterized by ribbons connected to the current Red List status for each species. The numerical values below each family name depict the relative percentage with the associated Red List category: CR = Critically Endangered, EN = Endangered, VU = Vulnerable, NT = Near Threatened, LC = Least Concern, and DD = Data Deficient. Two endemic and threatened frogs are illustrated by Atelopus coynei (Critically endangered) distributed in northern Andes of Ecuador, whereas Excidobates condor (Endangered) is distributed in the Cordillera del Condor, southeastern Ecuador. Both species are threatened by habitat loss, mining, and climate change. Illustrations by PARG.

Fig 4. High resolution (30 m x 30 m) Environmental Risk Surface (ERS) model for Ecuadorian amphibians.

Values of the ERS range from 0 (Green, low) to 1 (Red, high) to represent threat intensity. Shaded areas correspond to the National System of Protected areas shown in Fig 1.

Fig 5. Major threats associated with amphibian taxa (% of locality records in the database) by conservation categories in Ecuador.

Environmental contractions on climate change scenarios for RPC4.5 and RPC 8.5 are shown for those species with more than 50% of shift.

Fig 6. Cumulative species richness for threatened taxa (n = 265 models) by Red List category.

Maps with cumulative species (Num sp) models per category and family are shown in S3–S5 Figs.

Fig 7

Occurrence data of threatened Ecuadorian amphibians by (a) taxonomic families, (b) endemic taxa to Ecuador, and (c) Red List categories in an altitudinal gradient. Risk categories: CR = Critically Endangered, EN = Endangered, VU = Vulnerable, NT = Near Threatened, DD = Data Deficient. Least Concern taxa have been removed.

Fig 8

Occurrence data of NT (green), DD (grey), and NE (blue) Ecuadorian amphibian species, by Red List category and family. Only families with species in these categories are shown.

Fig 9. Frequency of locality records of amphibians in each risk category by natural regions in Ecuador.

Categories: CR = Critically Endangered, EN = Endangered, VU = Vulnerable, NT = Near Threatened, DD = Data Deficient. Least Concern taxa have been removed from this figure.

Fig 10. The IUCN Red List of amphibians from Ecuador representation in the National System of Protected Areas.

Categories: CR = Critically Endangered, EN = Endangered, VU = Vulnerable, NT = Near Threatened, LC = Least Concern, DD = Data Deficient. SNAP–Governmental National System of Protected Areas, from the Spanish acronym.