Caracterização da diversidade filogenética e o legado de paisagens em comunidades de peixes de riacho

Abstract

Freshwater fish constitute the most diverse group of continental vertebrates recorded, in which the aquatic ecosystems they inhabit are in constant and complex connection with the vegetative area around them. Furthermore, changes in riparian vegetation and how they impact the biodiversity of the aquatic environments with which they interact are being studied, although there are still many knowledge gaps. The present work aims to investigate the phylogenetic diversity of fish communities from 38 streams sampled in 2003 and 2013 in the Brazilian Southeast region (a period marked by intense conversion of pasture areas into sugarcane areas). The results from the generated phylogenetic tree showed the 54 identified species dispersed over 16 families and 5 orders. The main phylogenetic diversity metrics calculated reinforced the relationship between richness and phylogenetic diversity at the metacommunity level, in addition to allowing the observation of high values of evolutionary distinctiveness (ED) both in endemic species and in non-native generalist species. The investigation of the phylogenetic diversity (PD) of each stream and analysis of the correlation of this diversity with variations in environmental gradients related to land use showed little direct correlation between the variables. However, we observed a weakening trend in the correlations in the comparison between 2003 and 2013, indicating the possibility of the legacy of these changes in land use making these relationships even more complex. In summary, the study offers new perspectives on the phylogenetic diversity of freshwater fish communities and highlights the importance of a holistic approach to the conservation of these ecosystems. In addition, it is essential to understand that the environmental gradient that surrounds each stream is complex and the analyzes start from regions that already have a long history of recurrent environmental changes that are not duly registered. Such conclusions reinforce the need for monitoring biodiversity and changes in the regions, to allow more assertive conclusions of the ecosystemic consequences, in addition to effective policies for their conservation.