Environmental Drivers of Fish Taxonomic Distinctness and Functional Diversity in a Tropical River Basin

ABSTRACT Biodiversity studies have traditionally focused on species rank, yet recent research highlights the inadequacy of this approach alone. Instead, scientists emphasise taxonomic and functional surrogacy methods, such as indices of taxonomic distinctness and functional diversity, to grasp the relationships among species and their functional characteristics within ecosystems. Despite being a significant river in the Deccan Plateau region, understanding of the taxonomic distinctiveness and functional diversity of the fish community of the Bhima River basin remains elusive. Thus, we conducted this study to understand the relationship between these indices and environmental drivers affecting the fish community in the Bhima River basin. We studied taxonomic distinctness ( Δ + ), variation in taxonomic distinctness ( λ + ), functional dispersion (FDis), functional divergence (FDiv) and functional evenness (FEve) of the fish community. By correlation and regression analyses, we found a significant association between taxonomic distinctness and functional diversity indices. We also found that these indices are mainly influenced by annual temperature range, mean temperature diurnal range and precipitation of the dry season. We recommend conducting a comprehensive assessment of fish populations and studying the potential effects of climate change on fish diversity to improve understanding of their distribution in the Bhima River basin.