985 resultados para SQUAMATE PHYLOGENY


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Females of simuliid black flies are haematophagous insects and vectors of several pathogenic agents of human diseases such as the filarial worms Mansonella ozzardi and Onchocerca volvulus. The genus Cerqueirellum is one of the most important groups of vectors of mansonellosis and onchocerciasis diseases in South America, and the genera Coscaroniellum and Shelleyellum are phylogenetically close to Cerqueirellum. There is not yet an agreement among authors about the generic classification of the species which compose these three genera, being all lumped by some taxonomists within Psaroniocompsa. A cladistic analysis of all species of Coscaroniellum, Cerqueirellum, and Shelleyellum, based on 41 morphological characters were done. Species closely related to Cerqueirellum were included in the analysis. The genera Cerqueirellum, Coscaroniellum and Shelleyellum were demonstrated as consistent basal entities and well-defined monophyletic clades.

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Mitochondrial DNA (mtDNA) haplogroup L2 originated in Western Africa but is nowadays spread across the entire continent. L2 movements were previously postulated to be related to the Bantu expansion, but L2 expansions eastwards probably occurred much earlier. By reconstructing the phylogeny of L2 (44 new complete sequences) we provide insights on the complex net of within-African migrations in the last 60 thousand years (ka). Results show that lineages in Southern Africa cluster with Western/Central African lineages at a recent time scale, whereas, eastern lineages seem to be substantially more ancient. Three moments of expansion from a Central African source are associated to L2: (1) one migration at 70-50 ka into Eastern or Southern Africa, (2) postglacial movements (15-10 ka) into Eastern Africa; and (3) the southward Bantu Expansion in the last 5 ka. The complementary population and L0a phylogeography analyses indicate no strong evidence of mtDNA gene flow between eastern and southern populations during the later movement, suggesting low admixture between Eastern African populations and the Bantu migrants. This implies that, at least in the early stages, the Bantu expansion was mainly a demic diffusion with little incorporation of local populations.

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The Roeboides microlepis species-group is revised. Four species are recognized: R. myersii Gill, 1870 from the Amazon basin, R. microlepis (Reinhardt, 1851) from river Paraguay, middle and lower river Paraná, R. araguaito sp. nov. from the river Orinoco basin, and R. margareteae sp. nov. known only from Rio Parnaíba and Pindaré-Mearim, northeastern Brazil. The type-locality of R. microlepis is restricted to river Paraguay; R. bonariensis (Steindachner, 1879) is considered a synonym of R. microlepis. The phylogenetic analysis indicates that R. myersii and R. araguaito are most parsimoniously related and may be a sister group. These two species are here considered as sister group of the monophyletic lineage which includes R. microlepis and R. margareteae. A key to the microlepis species-group genus Roeboides is given.

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The relationship between body size and geographic range was analyzed for 70 species of terrestrial Carnivora ("fissipeds") of the New World, after the control of phylogenetic patterns in the data using phylogenetic eigenvector regression. The analysis from EcoSim software showed that the variables are related as a triangular envelope. Phylogenetic patterns in data were detected by means of phylogenetic correlograms, and 200 simulations of the phenotypic evolution were also performed over the phylogeny. For body size, the simulations suggested a non-linear relationship for the evolution of this character along the phylogeny. For geographic range size, the correlogram showed no phylogenetic patterns. A phylogenetic eigenvector regression was performed on original data and on data simulated under Ornstein-Uhlenbeck process. Since both characters did not evolve under a simple Brownian motion process, the Type I errors should be around 10%, compatible with other methods to analyze correlated evolution. The significant correlation of the original data (r = 0.38; P < 0.05), as well as the triangular envelope, then indicate ecological and adaptive processes connecting the two variables, such as those proposed in minimum viable population models.

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A new molecular phylogeny for akodontine rodents from Brazil was proposed. The phylogenetic tree was enriched with the area of occurrence and with information on the karyotype of the samples. Based on this enriched tree, and with a described methodology, hypotheses were proposed on the karyotype and area of occurrence of the ancestors of each Clade. Thus it was possible to discuss hypotheses on chromosome evolution of the group, and on dispersion events from the "area of original differentiation" of akodontines in the Andes. Chromosome evolution started with high diploid numbers (2n=52) and showed a tendency to reduction (until 2n=14 in more recent clades). Independent side-branches of the tree showed 2n reduction and in one case the 2n increased. At least four dispersion events from the Andes down to South-eastern Brazil were proposed. The results should suggest the direction of new studies on comparative karyology.