RESUMEN
Abstract It is repeatedly stressed the need to characterize the extant biodiversity in tropical ecosystems. However, inventory studies are still progressing slowly in dry ecosystems, leading to the underestimation of their true biodiversity and hindering conservation efforts. In this study, we present primary and secondary data, along with an updated list of amphibians and reptiles from two localities in the São Francisco-Gurguéia region in Piauí. Additionally, we compare the species composition between nine areas within the Caatinga, which were sampled using standardized methods over the past ten years, to examine broader spatial patterns of community composition. To survey reptiles and amphibians, we employed similar methods and sampling efforts in two areas within the Serra das Confusões National Park (SCNP) region. Our surveys recorded a total of 73 species of amphibians and reptiles, of which 24 are new distribution records for the SCNP region. Consequently, our findings increase the known herpetofauna in the region to 94 species. Despite their proximity, the two sites in the SCNP region exhibited only 42% similarity in species composition, and they differed significantly from other areas within the Caatinga. Furthermore, even the closer Caatinga areas presented differences in species composition, highlighting the necessity to evaluate biodiversity across the landscape and contribute to understanding biogeographic patterns.
Resumo É repetidamente enfatizada a necessidade de caracterizar a biodiversidade vivente em ecossistemas tropicais. No entanto, os estudos de inventário ainda estão progredindo lentamente em ecossistemas secos, levando à subestimação de sua verdadeira biodiversidade e dificultando os esforços de conservação. Neste estudo, apresentamos dados primários e secundários, juntamente com uma lista atualizada de anfíbios e répteis de duas localidades na região de São Francisco-Gurguéia, do Piauí. Além disso, comparamos a composição de espécies entre nove áreas dentro da Caatinga, que foram amostradas usando métodos padronizados nos últimos dez anos, para examinar padrões espaciais mais amplos de composição da comunidade. Para estudar répteis e anfíbios, utilizamos métodos e esforços de amostragem semelhantes em duas áreas na região do Parque Nacional da Serra das Confusões (PNSC). Nossos levantamentos registraram um total de 73 espécies de anfíbios e répteis, das quais 24 são novos registros de distribuição para a região do PNSC. Consequentemente, nossos resultados aumentam a herpetofauna conhecida na região para 94 espécies. Apesar da proximidade, os dois locais na região do PNSC exibiram apenas 42% de similaridade na composição de espécies e diferiram significativamente de outras áreas dentro da Caatinga. Mesmo áreas mais próximas da Caatinga apresentaram diferenças na composição de espécies, destacando a necessidade de avaliar a biodiversidade em toda a paisagem e contribuir para a compreensão de padrões biogeográficos.
RESUMEN
Preparation for oxidative stress (POS), i.e., the buildup of endogenous antioxidants during metabolic depression or low oxygen stress conditions, has been observed in at least 8 animal phyla under controlled conditions in laboratory. Despite the expected implications on the endurance to extreme environments and ecosystem occupation, the extent to which POS occurs in animals under natural conditions remains unexplored. Therefore, we took advantage of the natural history of the Brazilian Caatinga's frog Proceratophrys cristiceps to investigate the modulation of endogenous antioxidants and redox balance in their skeletal muscle and to verify if POS occurs under natural conditions. Expectedly, estivating frogs had low levels of the oxidative metabolism enzymes. Citrate synthase and isocitrate dehydrogenase activities were 36% and 25% lower than those in active frogs respectively. We found an overall upregulation of antioxidants in estivating P. cristiceps. Reduced glutathione concentration was 61% higher in estivating frogs than that in active animals. During estivation the activities of the hydroperoxide detoxification enzymes catalase, glutathione peroxidase, and glutathione H2O2-peroxidase were 48%, 57%, and 78% greater than those during the rainy season. Moreover, estivating frogs had a 47% lower ratio of disulfide to total glutathione levels than active frogs. Our findings confirm the occurrence of 'preparation for oxidative stress' in naturally estivating frogs and paves the way for further research on the redox biology of animals under natural settings. Such approach might reveal biochemical strategies under ecologically relevant scenarios.