Anuran assemblages in western Philippines: Unraveling the effects of habitat types, water availability, and elevation

Abstract

Understanding the patterns and drivers of species assemblages is the central tenet of community ecology and this may inform effective conservation and management strategies. Such information is scarce in tropical regions, particularly the Palawan faunal region and island group in the western Philippines. Here we examined the patterns of anuran richness and identified correlations in species co-occurrences and their shared responses to habitat types, water availability, and elevation. We sampled anuran populations using standardized transects established across Palawan's major islands between 2013 and 2019. We generated interpolated and extrapolated richness using Hill numbers. To investigate species co-occurrences and the relative importance of environmental variables, we used Joint Species Distribution Model (JSDM). A total of 18 anuran species were recorded, including seven non-endemic and 11 species restricted to Palawan. Anuran richness was highest in forests habitats than in cultivated land areas. Sites with water sources had higher anuran richness than those without water. Species richness observed along elevational gradient exhibited a hump-shaped pattern. Significant positive correlations in species co-occurrences were found among aquatic and semi-aquatic species. Anuran species showed tight associations with elevation and water availability, indicating that these variables are strong predictors of anuran co-occurrences. Finally, this study broadens our understanding of the differences and similarities in habitat requirements among anuran species, highlighting the need to consider such information when developing conservation strategies other than the traditional vulnerability and irreplaceability measures.