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| Author(s): |
Rafael Splendore de Borba
Total Authors: 1
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| Document type: | Doctoral Thesis |
| Press: | Rio Claro. 2018-04-11. |
| Institution: | Universidade Estadual Paulista (Unesp). Instituto de Biociências. Rio Claro |
| Defense date: | 2018-03-13 |
| Advisor: | Patricia Pasquali Parise Maltempi; Sandra Mariotto |
| Abstract | |
The Ancistrus genus is one of the most diverse of the Ancistrini tribe possessing 64 nominal species. These fishes differ from the other loricariids by the absence of plaques and odontodes at the tip of the muzzle, where there are only small fleshy tentacles and well-developed interopercular odontodes. The genus is characterized by showing great cytogenetic variability with the diploid number ranging from 2n = 34 and 2n = 54 chromosomes. Ancistrus is also widely distributed in the Uruguay, Paraguay and Amazon basins, with the latter two showing the greatest diversity of species and karyotypes of the genus. Despite these characteristics, the group is still known to present dubious taxonomy species that are difficult to identify, so that the phylogenetic relationships and phylogeographic patterns, especially in the Amazon and Paraguay basins, have not yet been revealed. In this sense, the present work aimed to discriminate the different Ancistrus lineages from the Amazon and Paraguay basins using the DNA barcoding tool, as well as to identify the phylogenetic and phylogeographic relationships of these lineages using multiple DNA sequences. 146 sequences of the Cytochrome Oxidase Subunit I (COI) gene were obtained, which were used to discriminate the lineages. The analysis of DNA barcoding showed the occurrence of seven lineages of Ancistrus in the Amazon basin and eight lineages in the Paraguay basin. The technique also revealed a high average genetic distance among these lineages (8.4%), indicating a high level of genetic isolation among them. In the phylogenetic analyzes, 93 concatenated sequences of the mitochondrial ATP synthase subunits 6 and 8 (ATPase 6/8) and COI and sequences of the Rag2 nuclear gene were used, whereas in the phylogeographic analysis only the ATPase 6/8 gene sequences were used. In the topology generated by the Bayesian method, 3 clades were distinguished, subdivided into 21 groups. The clades show a monophyletic relationship among the lineages from Paraguay and Amazon basins, and the 21 identified groups present high average genetic distance (8.4%). In the haplotype network, eight large groups were observed: seven belonging to the Paraguay basin and one corresponding to the Amazon basin, and there was no haplotype sharing between the two basins. These results indicate that Ancistrus forms a monophyletic unit in the Paraguay and Amazon basins, and these lineages have a high level of divergence and genetic isolation among them. This corroborates the existence of cryptic species in these regions and points out the need for a taxonomic revision for the genus in Paraguay and Amazon basins. (AU) | |
| FAPESP's process: | 13/17826-9 - PHYLOGENETIC AND PHYLOGEOGRAPHIC RELATIONS AND MOLECULAR DISCRIMINATION OF THE ANCISTRUS GENUS SPECIES KNER, 1854 (SILURIFORMES: LORICARIIDAE) THAT COMPOSE THREE WATERSHED OF THE MATO GROSSO STATE, BRAZIL. |
| Grantee: | Rafael Splendore de Borba |
| Support Opportunities: | Scholarships in Brazil - Doctorate |