| Grant number: | 05/01299-3 |
| Support Opportunities: | Regular Research Grants |
| Start date: | December 01, 2005 |
| End date: | February 28, 2009 |
| Field of knowledge: | Biological Sciences - Zoology - Taxonomy of Recent Groups |
| Principal Investigator: | Fernando Portella de Luna Marques |
| Grantee: | Fernando Portella de Luna Marques |
| Host Institution: | Instituto de Biociências (IB). Universidade de São Paulo (USP). São Paulo , SP, Brazil |
| City of the host institution: | São Paulo |
Abstract
Among the groups of Neotropical freshwater fishes of marine origin, there is a unique group of elasmobranchs taxonomically included within the family Potamotrygonidae. Members of Potamotrygonidae represent the only elasmobranchs exclusively restricted to freshwater; although they belong to a large group of rays predominantly marine (Myliobatiformes) of which some members occasionally invade brackish water environments. Morphological end molecular evidences suggest that the family Potamotrygonidae is a monophyletic taxon, sister group of amphi-Americam member of Himantura, and possibly derived from a Caribbean marine ancestor via marine incursion to the Paleo-Amazon-Orinoco during the Miocene. The complex origin of potamotrygonids resulted in a parasite fauna represented by groups predominantly marine and others endemic to freshwater. This makes this system an interesting model to study historical associations among parasites, hosts, and biogeographical areas. The parasite fauna inhabiting potamotrygonids is poorly known and the processes responsible for the patterns of diversification of these organisms depend still on the description of the diversity of parasites associated with potamotrygonid. Although recent studies have documented the cestode fauna of potamotrygonids, other groups have never been addressed satisfactorily. In addition, even the diversity of potamotrygonids themselves lack taxonomic treatment; for some nominal species persist without unambiguous definition. That is particularly true for species with widespread distribution. This proposal attempts to contribute to our present understanding of this host/parasite complex focusing on the diversity of a group of parasites for which to date only two nominal species are known and on the definition of the limits of a host species that lacks unequivocal definition. Within this framework, the objectives of this research proposal are: (1) to describe the diversity of Monogenoidea parasites of Potamotrygonidae using morphological and molecular data; (2) to propose a phylogenetic hypothesis of this group of parasites based on total evidence (i.e., simultaneous phylogenetic analysis of morphological and molecular data); (3) to characterize the components and the historical structure of the parasite fauna of monogenoids of Potamotrygon orbignyi from different hydrographic basins; (4) to erect a phylogeographic hypothesis for P. orbignyi based on molecular data; and (5) to elucidate the coevolutionay and biogeographical processes responsible for the diversification patterns of this host/parasite system in different temporal scales (i.e., biogeographic and phylogenographic). (AU)
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