Padrões de diversidade β e diversidade funcional durante a colonização e sucessão de algas perifíticas em ambiente lêntico no semiárido.

Abstract

Biological diversity can be accessed by β diversity and functional diversity. The components of β diversity becomes a powerful tool for understanding the ecological succession process. The SDR-simplex approach provides a tool to the calculation, visualization and interpretation of diversity β for access components of similarity, replacement of species, species differences, turnover, nesting and agreement of species. Functional diversity refers to the measurement of the values or range of values, of trace species that affect one or more aspects of ecosystem functioning, and can be quantified by the potential resources available to the community who are in disuse, the degree of distribution biomass of a community in a niche space and the niche differentiation. The study aimed to (a) describe the diversity of components β in periphyton assemblages in three ponds in semiarid region and (b) verify the relationship between β diversity and environmental variables, (c) identify patterns of change in functional wealth and functional divergence along of the succession gradient and (d) test the linear models and non-linear, exponential, logarithmic and logistics, the best fit the relation between functional richness and species, and among functional divergence and diversity of species. Colonization and succession took place during 35 days in polyethylene terephthalate substrates, measuring 2 x 5 cm in three lagoons of the municipality of Picos, Piauí. Nine samples were taken during the colonization period, with sampling substrate for determining the composition (n = 3) and density (n = 3). Physical and chemical parameters of water were measured in situ and aliquots of 1 liter of water were collected for determination of nutrients in the water. An RDA was used to relate the species distribution and environmental variables. The β diversity components have been accessed through the SDR-simplex approach, followed by a Mantel test to check the influence of environmental variables on the β diversity and multivariate dispersion homogeneity test to check the β diversity patterns across ponds. For determine the functional diversity, the algae were classified according to their functional characteristics (fixation, growth, adhesion and size), followed by determination of the functional richness, species richness, functional divergence and diversity of species. The Bayesian information criterion is used to identify the best fit model of the relationship between richness and functional richness and diversity of species and functional diversity. Patterns in diversity β along the succession show significant responses in relation to environmental differences. β diversity patterns between the ponds were best represented by components based on abundance. Functional diversity results suggest a high functional redundancy among the pioneer species, giving the community more resilient to disturbances in the initial phase and transition security to the next phase. It identified a logistic behavior between the components of the functional diversity and the diversity of species characterized by a rapid increase in load and differentiation of niches.