Macroecologia Microbiana: dispersão bacteriana em lagos rasos distribuídos pelo estado de São Paulo
Studies in microbial ecology have had rapid advances in the last decades, in part due to the influence of technological innovations that allowed us to perceive a much greater microbial diversity than was previously found. There are increasing evidences that ecological patterns previously attributed only to macro-organisms can also be observed in microorganisms, a fact that brings the study of microorganisms closer to the application of theories and models already consecrated in classical ecology. Still, the contribution of microorganisms to theoretical ecology is still in its infancy. The present dissertation aims to study the patterns of spatial distribution in prokaryotic organisms of dozens of small lakes inserted in a tropical region in a perimeter of more than 3000 km. This thesis is divided in four chapters, first focusing on the historical context of ecological studies related to spatial attributes of species distribution, which was the basis for the creation of new paradigms such as metapopulations and metacommunities, and discussed the advances of microbiological studies in convergence with these new paradigms and how molecular technologies have contributed to bring microbial ecology closer to general ecology. The second chapter aims to present in a more detailed view on the methods used, problems faced and their solutions, in order to facilitate future studies where the same techniques of extraction, sequencing and data processing (bioinformatics) need to be applied. In the third chapter two well-known extraction methods were tested to evaluate their influence in indices commonly used in ecological studies. The last chapter demonstrates the presence of a bimodal distribution of occupancy-frequency distribution through the analysis of 60 shallow lakes near springs distributed in a large-scale matrix covering the entire state of São Paulo, a pattern already widely demonstrated for macro-organisms, but not yet tested in freshwater bacteria. In addition, the most abundant bacterial groups among the 'core' organisms and the most diverse among the 'satellite' and their potential relevance for the communities in which they were inserted were evaluated. This study is a contribution of microbial ecology to general ecology, aiming at a full understanding of the processes that drive the composition of microbial communities in a given environment.