Banca de DEFESA: SILVIA BRITTO BARRETO

Uma banca de DEFESA de DOUTORADO foi cadastrada pelo programa.
DISCENTE : SILVIA BRITTO BARRETO
DATA : 29/08/2019
HORA: 14:00
LOCAL: Salão Nobre do Instituto de Biologia da UFBA
TÍTULO:

Phylogeography, hybrid zone and speciation in lineages of Nematocharax (Characiformes: Characidae)

PALAVRAS-CHAVES:

coastal basins, river captures, diversification, Neotropics, paleodrainages.

PÁGINAS: 150
GRANDE ÁREA: Ciências Biológicas
ÁREA: Zoologia
RESUMO:

The Neotropical region harbors the richest freshwater ichthyofauna of the world, with taxonomical issues that generate conflicts in the definition of boundaries between species and complex biogeographic histories that are still poorly understood. In this region, fish of the genus Nematocharax represent an interesting model for studies on speciation and hybridization, due to genetic and morphological divergences described for the group. Therefore, this thesis investigated evolutionary processes in this group, as well as their relationship with the geological evolution of hydrographic basins of the Northeast Atlantic Forest freshwater ecoregion, which stands out for its extensive topographic variation and high endemism of fish. In chapter 1, it was evidenced that the high divergence of a lineage from the Upper Contas river in genetic and morphological characters allows to recognize it as a new species of Nematocharax, restricted to the Chapada Diamantina region. In this work, its diagnosis and description are then given, and its conservation status is evaluated. In chapter 2, we investigated how the diversification history of Nematocharax occurred in a spatio-temporal context based on the geographical distribution and genetic structure of its lineages. As results, we found that, different from what occurs in Southern Brazil, the continental shelf of the Northeast is considerably narrower, and the paleodrainages do not explain the phylogeographic pattern found, so that drainage rearrangement events in the interior of the continent probably played a more significant role in the diversification of fish in this area during the Pleistocene. Finally, in chapter 3, we investigated the hybridization process in the contact area between divergent mitochondrial lineages of Nematocharax in drainages from the Lower Contas river, and we showed how genetic and morphological characters vary along the transect of this hybrid zone, with the identification of genomic regions with abrupt clines and, therefore, probably under selection. In addition, the results suggest an old history of hybridization, with predominance of pure individuals and F2 offspring, in a scenario of low dispersal of parental genotypes to the center of the cline and of hybrids out of the center of the cline. The data of this thesis allowed to understand the evolutionary history of Nematocharax and to test hypotheses of diversification of its lineages, being possible to correlate distribution patterns and geological events, such as river captures and formation of paleodrainages, that provided connection and vicariance between basins. In addition, it was possible to elucidate the dynamics of a hybrid zone and to understand the evolutionary mechanisms responsible for its origin and maintenance.

MEMBROS DA BANCA:
Externo à Instituição - ANDRÉA TONOLLI THOMAZ - UBC
Presidente - 2048980 - HENRIQUE BATALHA FILHO
Interno - 1349793 - MARCELO FELGUEIRAS NAPOLI
Interno - 3062387 - PRISCILA CAMELIER DE ASSIS CARDOSO
Externo à Instituição - SERGIO MAIA QUEIROZ LIMA - UFRN