Where are the survivors? Tracking relictual populations of endangered frogs in Costa Rica

Abstract

Aim We used abiotic environmental variables and historical locality records to infer distributions of endangered anuran species of Costa Rica to promote efficient strategies for future amphibian surveys. Location Costa Rica. Methods We used a Maximum Entropy Algorithm (Maxent) to predict potential distribution maps for 17 species of endangered anurans and create a consensus map of species richness. We compared the environmental conditions from localities where relictual amphibian populations were recently rediscovered with the conditions across their historical range to evaluate the possibility that these relictual populations might occur in specific climatic conditions that could explain their persistence. We used a multicriteria analysis considering the following factors: the intersection zones between the consensus map, conservation areas, potential Batrachochytrium dendrobatidis (Bd) distribution, collecting effort and areas within the precipitation range at which reappearances had occurred to locate sites for future surveys. Results The resulting predictions suggest that suitable areas for the highest number of species occur between 1300 and 2500 m.a.s.l and are concentrated along the Pacific slopes of the Cordillera de Talamanca and Cordillera Volcánica Central. Around 45% of the high potential richness area is under protection. Relictual populations of declined species seem to persist mainly in highly humid localities (2500–3500 mm of mean annual precipitation). Around 240 km2 has an ideal environment for the rediscovery of relictual populations. The multicriteria analysis showed that around 0.5% of the Costa Rican territory should be surveyed exhaustively for frogs. Main conclusions Many of the potential refugia we identified here have not been surveyed since 2000, the areas identified by the best model predictions correspond well with the localities of the relictual populations recently reported. We suggest future surveys of missing amphibian species should focus on these areas. The discovery of populations of endangered species can be used to propose conservation areas.

Infection with Batrachochytrium dendrobatidis is common in tropical lowland habitats: Implications for amphibian conservation

“…Furthermore, conducting more seasonal sampling in lowlands will increase the record of presence–absence datasets on Bd and can be used to generate more robust species distribution models (SDMs) from nonopportunistically collected data (Puschendorf et al, ). SDMs can help identify hotspots for future outbreaks of Bd and can be used to predict potential locations for amphibian rediscoveries (García‐Rodríguez et al, ; Puschendorf et al, ). Recent validation surveys have led to the discovery of relict peripheral populations that occur in potential environmental refuges from disease (Puschendorf et al, ; Raffel & Fox, ; Scheele, Hunter, Skerratt, Brannelly, & Driscoll, ), validating increased surveys outside the boundaries of core geographic distributions (Abarca, Chaves, García‐Rodríguez, & Vargas, ; Chaves et al, ; González‐Maya et al, ; Jiménez & Alvarado, ; Nishida, ).…”

“…Despite the focus on highlands for most Bd‐related studies, the few studies conducted in lowlands of Central America have found new locations where this pathogen occurs, suggesting that Bd is more widely distributed than previously thought (Flechas, Vredenburg, & Amézquita, ; Kilburn et al, ; von May, Catenazzi, Santa‐Cruz, & Vredenburg, ; Whitfield et al, ; Whitfield, Kerby, Gentry, & Donnelly, ; Woodhams et al, ; Zumbado‐Ulate et al, ). Predictive models and abiotic suitability for Bd across heterogenous landscapes (Brannelly, Martin, Llewelyn, Skerratt, & Berger, ; García‐Rodríguez, Chaves, Benavides‐Varela, & Puschendorf, ; Puschendorf et al, ; Rödder et al, ) can be generated using available bioclimatic databases such as WorldClim. This dataset contains 19 bioclimatic variables generated by land area interpolations of climate point data from 1950 to 2000.…”

Renewing hope: the rediscovery of Atelopus varius in Costa Rica

“…These findings follow a pattern similar to our finding in that species considered extinct or near-extinct, with recorded massive declines due to chytrid have been rediscovered at previously known locations. Recent analyses suggest that certain areas of Costa Rica have high probabilities of re-discovering populations, and most have not been sampled since 2000 (García-Rodríguez et al, 2012). Our locality is one of these areas which fall within predicted priority regions for surveys and conservation.…”

Living quarters of a living fossil—Uncovering the current distribution pattern of the rediscovered Hula painted frog (Latonia nigriventer) using environmental DNA

“…Usage of presence data to identify landscape factors that are associated with species distribution and to construct habitat suitability maps is an approach increasingly applied in ecology and conservation practice in general (for a review, see Guisan & Zimmermann, 2000), and in the study of endangered amphibians in particular (Blank & Blaustein, 2012;Garc ıa-Rodr ıguez, Chaves, Benavides-Varela, & Puschendorf, 2012). Nevertheless, the performance of such models is poor when sample size is small (Wisz et al, 2008), as is usually the case for rare and elusive species.…”