Name: RAFAELA DUDA PAES
Type: PhD thesis
Publication date: 07/04/2017
Advisor:
Name |
Role |
|---|---|
| Leonora Pires Costa | Advisor * |
| Marcelo Weksler | Co-advisor * |
Examining board:
| Name |
Role |
|---|---|
| Alexandre Reis Percequillo | External Examiner * |
| Ana Carolina Loss Rodrigues | Internal Examiner * |
| Bárbara Maria de Andrade Costa | External Examiner * |
| Cecília Waichert Monteiro | Internal Examiner * |
| Leonora Pires Costa | Advisor * |
| Pablo Rodrigues Gonçalves | External Alternate * |
| Yuri Luiz Reis Leite | Internal Alternate * |
Summary: Oecomys bicolor is a small oryzomine rodent with a wide geographic distribution through Central America to Brazil. His taxonomy is not yet well established, since morphological data assign ten synonyms to this species, while genetic information shows more clades and points to a species complex. Studies based on cytochrome b sequences indicate groups with low averages intraclade divergences (< 2%), but with higher interclade divergences. Also, only one research associated genetic and morphological characters, which are polymorphic. Mitochondrial genes accumulate homoplasies fastly and, for so, lose resolution as the depth of the tree branches increases, which encourages the inference of multigene phylogenies with nuclear locus, since the slow rates of evolution are useful to recover deeper relationships. In order to elucidate the taxonomy of the group, this work aims to present a phylogenetic hypothesis to the O. bicolor complex, using qualitative and quantitative morphological data of exemplars of all age classes, covering the geographic distribution across the Americas, as well as phylogenetic analyses with partial sequences of one mitochondrial and two nuclear markers. The results recovered a paraphyletic O. bicolor, with 11 geographically structured clades, which are accompanied by diagnosable morphotypes. Among them, two lineages are recognized as O. bicolor sensu stricto (widely present in the Amazon and trans-Andean forests) and O. cleberi (endemic to the Cerrado, Pantanal and Amazon of Brazil, exclusive to the distribution of O. bicolor), one is revalidated as O. nitedulus (restricted to the Guianas) and eight are potential new species, of which five are described (distributed in Amazonia, with cases of sympatry and limitation by the Tapajós River). The propositions made on the revalidation of O. nitedulus and the recognition of eight new lineages increase the number of Oecomys species from 17 to 26. Moreover, three other nominal taxa represent potential species complexes, evidencing the difficulty in identifying species of the genus and the need for more taxonomic revisions.
