Functional traits and environment drive montane amphibian distribution in the southern Philippines

Montane amphibians are vulnerable to environmental and climatic changes. Species response to these changes can be better understood by analyzing how amphibian communities differ along environmental gradients. We utilized both taxonomic and functional approaches to determine patterns of distribution in montane amphibians in the southern Philippines. We tested habitat variables to explain distribution and filtering of montane amphibian traits from lowland evergreen to upper montane forests. We recorded 24 species of amphibians from seven families. Multivariate tests revealed different species composition of montane amphibians among forest types. Amphibian diversity decreased and endemism increased from lowland evergreen to upper montane forest. Elevation, shrub foliar cover, and tree basal area explained most of the variations in amphibian distribution. Species richness decreased with these habitat variables while abundance decreased with shrub foliar cover. Fourth-corner modeling showed that elevation had the strongest effect on traits, particularly those related to habitat use, larval ecology, and resource acquisition. Our results suggest that both functional traits and environment were interacting in driving the pattern of montane amphibian distribution, highlighting the additive value of incorporating functional traits in understanding amphibian distribution patterns and community assembly mechanisms.