São os locais mais isolados espacialmente ou os ambientalmente mais diferentes que mais contribuem para a diversidade?

Abstract

One way to explain why species organize in such a way in space is through the calculation of beta diversity. In this study, I used the method proposed by Legendre and De Caceres (2013), which partitions the total beta diversity in species contribution to beta diversity (SCBD) and local contribution to beta diversity (LCBD). This approach allows us to understand the mechanisms responsible for generating and maintaining beta diversity in ecosystems. The aim of this study was to examine the relative contribution of the sites (LCBD) and species (SCBD) to the beta diversity in a floodplain, using both taxonomic and functional approaches (Morphologically Based Functional Group - MBFG). Additionally, it aimed to identify which morphologically based functional group had the greatest influence on the LCBD indices of the taxonomic community and the environmental variable related to the high LCBD values. I analyzed the phytoplankton community of 50 permanent lakes, connected and isolated, and tested the hypothesis that the contribution of the sites connected to the hydrological network will be lower than isolated sites. To investigate the influence of the groups on the LCBD indices, a multiple linear regression was conducted. For this regression, the value of total beta diversity (Bdtotal) and the indices of the ecological uniqueness (LCBD and SCBD) were calculated for each MBFG. Eight lakes contributed significantly to the beta diversity, of which only one was connected. The groups with the most substantial effect on the variation in taxonomic community indices were Groups V and VII. Among the species that contributed to beta diversity, 41% belong to the groups that had the greatest effect on the LCBD indices of the taxonomic community. Based on these findings, I conclude that the contribution to beta diversity in floodplains is influenced by hydrological connectivity, a factor that provides unique ecological conditions favoring a more singular species combination. I also found that functional group based on morphology can be used to examine the contribution of species to beta diversity. Considering the negative relationship found between conductivity and LCBD values, we further concluded that sites with special ecological conditions contribute more to beta diversity. The uniqueness in the species composition found, the LCBD indices, indicate the sites that contribute more or less to the beta diversity in the region and these results are useful for conservation studies of the area.