Banca de DEFESA: Natália Rodrigues Bijos

Uma banca de DEFESA de DOUTORADO foi cadastrada pelo programa.
STUDENT : Natália Rodrigues Bijos
DATE: 10/06/2024
TIME: 09:30
LOCAL: Auditório 4 e Plataforma Teams
TITLE:

"Taxonomic and phylogenetic diversity of herbaceous-shrub species in veredas (Brazilian savanna palm swamps) and factors that determine their composition and distribution"

KEY WORDS:

Wetlands, Herbaceous-shrub, Palm swamp, Cerrado, Environmental and spatial variables, Taxonomic beta diversity, Phylogenetic beta diversity, Stochastic process, Deterministic process

PAGES: 189
BIG AREA: Ciências Biológicas
AREA: Ecologia
SUMMARY:

Veredas are wet savanna physiognomies characterized as a vegetational complex in which an herbaceous-shrub layer dominates the landscape and the Mauritia flexuosa L. palm tree is distributed in its wetter zone. They are considered as "islands" of vegetation over saturated soils, embedded in a Cerrado savanna matrix over well drained soils. Understanding the taxonomic and phylogenetic alpha and beta diversities of veredas (Brazilian palm swamps) and their correlation with environmental (soil and climate) and spatial variables can provide insights for the management of this unique and endangered environment. Here we aim to assess how ecological and evolutionary processes affect the taxonomic and phylogenetic alpha and beta diversities of herbaceous-shrub species in veredas, and to identify the structuring process (based on neutral or niche theory) that influences these communities. To accomplish that we used the occurrence data of 560 herbaceous, subshrub, and shrub species available for 21 vereda sites (315 10-m transects) in central Brazil, together with their geographic coordinates, 12 soil physicochemical properties, and 14 bioclimatic variables. From this, we first assessed the species diversity in the veredas. We then verified the influence of soil variables on species composition using canonical correspondence analysis. To understand how soil physicochemical properties affect changes in species richness and cover, we used regression models. Secondly, we calculated the taxonomic β-diversity (TBD) indices of the veredas. Then we evaluated the correlation of soil, climatic and spatial factors with the species composition of the veredas using transformation-based Redundancy Analysis and variation partitioning. Finally, we constructed a phylogenetic tree of 540 vereda species and tested the relationship between phylogenetic metrics (alpha diversity) and environmental variables using ordinary least squares models. Afterwards, we examined the effects of soil distance, climatic distance, and spatial distance on phylogenetic β- diversity (PBD) using multiple regressions on distance matrices. Our results showed that the proportion of exclusive species in the veredas ranged from 4 to 38%, indicating that species distribution in the communities is mosaic-like. Vereda soils were acidic, with high levels of aluminum, organic matter, and sand, but low levels of phosphorus, magnesium, and calcium. Soil phosphorus, pH, organic matter, cation saturation, and sand proportion were important in understanding species composition (86% of the variation) and species richness (63%) in veredas. Phosphorus and pH were positively correlated with species richness, whereas organic matter was negatively correlated. Organic matter, cation saturation, and sand were negatively correlated with compositional similarity, but phosphorus was positively correlated. We observed that veredas with high floristic diversity had low fertility soils. Overall, there was high alpha and beta diversities in the studied sites and significant differences in the soil properties of the veredas when only soil factors were considered. Furthermore, we found that the plant communities were more influenced by the spatial turnover of species than by nestedness, with spatial predictors better explaining their composition and distribution. The most important environmental variables influencing the TBD of veredas are cation saturation, average temperature of the coldest quarter, precipitation of the coldest quarter, pH, annual precipitation, sand, and seasonal annual temperature. Finally, our findings revealed a pattern of phylogenetic clustering distribution in the veredas, reflecting the potential role of environmental filtering. Phylogenetic metrics were strongly influenced by bioclimatic variables and organic matter. The turnover component contributed more to PBD between sites than the nestedness component. Geographic, climatic, and soil distance matrices were mutually important to significantly explain the variance in PBD and in the turnover component. In summary, considering the TBD, stochastic processes, probably related to dispersal limitation, act in the formation of vereda communities. On the other hand, both phylogenetic clustering and phylogenetic dispersal act on the flora of veredas, indicating that the combined effect of niche and stochastic processes influences the PBD of these distinguished communities.

COMMITTEE MEMBERS:
Externa à Instituição - INGRID HORAK TERRA - UFVJM
Externo à Instituição - MARCELO FREIRE MORO - UFC
Interno - 404584 - AUGUSTO CESAR FRANCO
Presidente - 5192951 - CASSIA BEATRIZ RODRIGUES MUNHOZ
Interna - 1365470 - ISABEL BELLONI SCHMIDT