Metacomunidades bacterianas de sistemas aluviales: ¿Cuánto de azar hay en su estructura? How random are bacteria metacommunity assemblages in a complex floodplain system?

HUBER P.; METZ S.; MAYORA G.; UNREIN F.; DEVERCELLI M.

Valparaíso

Congreso; 1er CONGRESO ISME AMERICA LATINA; 2019

Determining which processes take place in the spatial distribution of bacterioplankton metacommunities has been a central goal of microbial ecology. In freshwater systems, selection has been spotted as the main driver shaping the structure of assemblages. However, its relative importance compared with other processes (i.e. dispersal, drift, speciation) may depend on spatial heterogeneity and dispersal rates within a metacommunity. Here, we design a spatio-temporal study in a complex floodplain system of Paraná River to investigate in which strength the deterministic and stochastic processes drive the structure of bacterial metacommunity. We hypothesized that the importance of the different processes depends mainly on hydrological connectivity that determines the environmental heterogeneity (EH). We used an analysis based on phylogenetic and taxa turnover and co-occurrence networks. We predicted that, as hydrological connectivity increases (i) bacterioplankton metacommunity is mainly driven by drift, leading to (ii) random associations between bacterial taxa. Contrary, we found that selection was the main driver of bacterial metacommunities regardless of hydrological periods. However, its relative importance as well as the type of selection, changed according to the EH. Homogeneous and heterogeneous selection had the major role in structuring the metacommunity in periods of high and low EH, respectively. However, in the period of intermediate EH, the relative importance of non-selection processes were twice as high as those of other periods. Additionally, changes in hydrological conditions significantly affected the associations between bacterial zOTUs being more random in the period of intermediate EH.