Banca de DEFESA: LETÍCIA BARBOSA QUESADO

Uma banca de DEFESA de DOUTORADO foi cadastrada pelo programa.
DISCENTE : LETÍCIA BARBOSA QUESADO
DATA : 26/06/2017
HORA: 14:00
LOCAL: Sala de Reuniões do Centro de Biociências
TÍTULO:

Spatial scale influence on geographic patterns of taxonomic and functional diversity of phytoplankton in semi-arid and coastal freshwaters ecosystems of Rio Grande do Norte

PALAVRAS-CHAVES:

Local factors; regional factors; β-diversity; functional diversity; functional redundancy; intraspecific variation; interspecific variation; phytoplankton; species sorting; turnover.

PÁGINAS: 142
GRANDE ÁREA: Ciências Biológicas
ÁREA: Ecologia
RESUMO:

We aimed to evaluate how the spatial scale influences the taxonomic and functional composition of phytoplankton in freshwater environments distributed along an arid gradient from the (humid region) coast to the countryside (semiarid region) of Rio Grande do Norte. Likewise, we also intended to verify (i) which factors (local or regional) determines taxonomic and functional β-diversity (Chapter 1); (ii) how the relationships between functional and taxonomic metrics (richness, evenness, diversity, and functional redundancy) vary according to spatial observation scale (lake or watershed) (Chapter 2); and (iii) how environmental gradients explain the variation of phytoplankton size and functional groups (Chapter 3). We collected samples in the subsurface of the limnetic region of 98 lakes distributed along 14 watersheds, between September and October 2012. The functional metrics were based on mixed traits, as surface, size, presence of mucilage and pigment composition (green, blue, brown and mixed) and type of life forms (colonial, filamentous or unicellular). Our results show that although the environment was spatially structured mainly by watershed, the importance of space in structuring phytoplankton increased with presented a slight increasing spatial scale. Phytoplankton community was structured by species sorting at the watershed level and by the region’s and watershed’s identity at larger spatial scale. The only exception was Piranhas-Açú watershed, in which space was already structuring the community due to the great distances between its lakes. There was a strong role of functional complementarity at the local level for structuring phytoplankton communities. Opposite to what we expected, functional β-diversity was not a good predictor of local factors. Once, functional redundancy became more influent at the metacommunity level. At the regional level, both approaches (taxonomic and functional) explaining almost the entire distribution of organisms and functional traits. A positive relationship was found between all the functional and taxonomic metrics of the community (richness, evenness, and diversity). Moreover, on the contrary of what we expected, only the functional-taxonomic richness relationship increased the power of explicability with increasing spatial scale. Although the functional redundancy index weighted by abundance presented low values, it increased slightly on average with the spatial scale and was inversely related to environmental heterogeneity. These results suggest a substantial role of functional complementary at local scale for structuring phytoplankton communities and the importance of the functional redundancy at metacommunity level to maintain local communities functionally. In general, there was an increase in the average size of the phytoplankton community, with a Cyclopoida and Rotifera biomass, and reduced light availability. The predominance of SPT repeated itself within each of the functional groups, except for the non-toxic unicellular algae with hard cell wall and the toxic filamentous algae for which intraspecific variation was more important than SPT along predator (Calanoida biomass) and resource gradient (total phosphorus), respectively.

MEMBROS DA BANCA:
Externo à Instituição - ADRIANO SANCHES MELO - UFG
Interno - 1837921 - ALEXANDRE FADIGAS DE SOUZA
Presidente - 1434166 - LUCIANA SILVA CARNEIRO
Interno - 1764855 - VANESSA BECKER
Externo à Instituição - VERA LUCIA DE MORAES HUSZAR - UFRJ