Ecological drivers of multiple facets of beta diversity using disparate biological groups and different taxonomic level across hierarchical spatial and temporal scales.

Abstract

Our knowledge on temporal and fine- and broad-scale patterns of biodiversity, as a basis for biogeographical models and conservation planning, have been few explored to two fundamental components of beta diversity: replacement and richness difference. Whether variability in these components of beta diversity is congruent in space and time for disparate biological groups, which show wide variation in functional traits (e.g., dispersal mode), is, hitherto, unknown. Moreover, one of the main standing paradigms is to understand whether the empirical biogeographic patterns of macro-organisms also apply to micro-organisms. This thesis consists of three papers. The first one aimed to determine whether the cross-taxon congruence of taxonomic and functional beta diversity and its components varies across space, and time. Our results showed how detailed hierarchical analyses can reveal hidden patterns of cross-taxon congruence. We partly supported the hypothesis that the strength of cross-taxon congruence generally decreases with the increase of functional distances between pairs of biological groups. In the second paper, we contrasted longitudinal patterns in the total beta diversity and its components in the last non-dammed stretch of the Paraná River for actively (fish) and passively (phytoplankton) dispersing biological groups. The results ratify that biodiversity patterns exhibited by single biological groups do not necessarily match those of other groups that show wide variation in biological features. Our findings have improved understanding of tributary-induced heterogeneity and highlight the importance of dam-free stretches of rivers for preserving its integrity. In the third paper, we used morphological data from live organisms and molecular data to verify which approach better explain the role of environmental and spatial predictors on the ciliates structuration, as well as clarify their biogeography. We found that environmental filters had a greater influence on the morphological than on the molecular site-by-site dissimilarities. Meanwhile, biogeographic factors and the distance among sites limit the distribution of molecular-based composition, resulting in significantly different species compositions in each of the floodplain-associated lakes analyzed. In summary, the findings of this thesis suggest that conservation biology and environmental assessment need to monitor different biological groups, as well as take into account for the choice of taxonomic resolution, as each group and approach provides unique insights.