Connectivity and phylogenetic diversity of a fish metacommunity in subtropical coastal lakes

Abstract Neotropical freshwater biodiversity is remarkable, mainly due to historical, biotic, and environmental processes. Landscape connectivity can promote or restrict species dispersal in fish metacommunities, thereby influencing the diversity and phylogenetic structure of communities. This study evaluated whether structural landscape variables of the Tramandaí River basin affect the phylogenetic diversity of the component communities of a fish metacommunity. The variables considered were primary and estuarine connection, lake shape and area, and distance from the sea. Phylogenetic diversity was estimated using a time-calibrated fish phylogeny and multiple phylogenetic diversity metrics, while the relationships between landscape variables and each metric were assessed using path analysis. The distribution of phylogenetic lineages across lakes was examined using Principal Coordinates of Phylogenetic Structure. The results revealed a negative effect of primary connection on the Nearest Relative Index and a negative effect of distance from the sea on the Nearest Taxon Index, as well as phylogenetic structuring associated with more isolated lakes and greater saline influence. The results highlight the importance of connectivity and distance from the sea in shaping the phylogenetic organization of fish metacommunities in the Tramandaí River basin, contributing to a better understanding of the processes that structure diversity in Neotropical coastal systems.