192 resultados para Phylogenetic analysis


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We re-evaluated the larval support for families within majoids using the Wilcoxon signed-rank test with emphasis on Inachoididae. To accomplish our objectives, we added 10 new taxa, two of which are traditionally assigned to the family of special interest, to a previous larval database for majoids, and re-appraised the larval characters used in earlier studies. Phylogenetic analysis was performed with PAUP* using the heuristic search with 50 replicates or the branch-and-bound algorithm when possible. Multi-state transformation series were considered unordered; initially characters were equally weighted followed by successive weighting, and trees were rooted at the Oregoniidae node. Ten different topological constraints were enforced for families to evaluate tree length under the assumption of monophyly for each taxonomic entity. Our results showed that the tree length of most constrained topologies was not considerably greater than that of unconstrained analysis in which most families nested as paraphyletic taxa. This may indicate that the present larval database does not provide strong support for paraphyly of the taxa in question. For Inachoididae, although the Wilcoxon signed-rank test rejected a significant difference between unconstrained and constrained cladograms, we were unable to provide a single synapomorphy for this clade. Except for the conflicting position of Leurocyclus and Stenorhynchus, the two clades correspond to the traditional taxonomic arrangement. Among inachoidids, the clade (Anasimus (Paradasygyius (Collodes + Pyromaia))) is supported, whereas for inachids, the clade (Inachus (Macropodia + Achaeus)) is one of the most supported clades within majids. As often stated, only additional characters will provide a better test for the monophyly of Inachoididae and other families within Majoidea.

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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

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The genus Mycetagroicus is perhaps the least known of all fungus-growing ant genera, having been first described in 2001 from museum specimens. A recent molecular phylogenetic analysis of the fungus-growing ants demonstrated that Mycetagroicus is the sister to all higher attine ants (Trachymyrmex, Sericomyrmex, Acromyrmex, Pseudoatta, and Atta), making it of extreme importance for understanding the transition between lower and higher attine agriculture. Four nests of Mycetagroicus cerradensis near Uberlandia, Minas Gerais, Brazil were excavated, and fungus chambers for one were located at a depth of 3.5 meters. Based on its lack of gongylidia (hyphal-tip swellings typical of higher attine cultivars), and a phylogenetic analysis of the ITS rDNA gene region, M. cerradensis cultivates a lower attine fungus in Clade 2 of lower attine (G3) fungi. This finding refines a previous estimate for the origin of higher attine agriculture, an event that can now be dated at approximately 21-25 mya in the ancestor of extant species of Trachymyrmex and Sericomyrmex.

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Specimens of Leptodactylus mystacinus from Brazil were karyotyped with conventional and differential staining. The 2n = 22 karyotype is similar to that found for the majority of the Leptodactylus, the karyotypic conservatism also confirmed by the similarity of the replication banding patterns with those previously described. L. mystacinus has a small amount of C-banded heterochromatin, located mainly at the centromeres, although telomeric or interstitial bands have also been noticed. With DA/CMA(3) some chromosome regions showed slightly bright fluorescence, and with DA/DAPI, no particular AT-rich repetitive region was observed. Silver staining showed an extensive inter- and intraindividual variation in the number and position of Ag-positive regions, in 1p, 4p, 8p, 8q, and 11p. Nevertheless, FISH using rDNA probes confirmed only the signals on the short arms of chromosomes 4 and 8 as true NORs. The remaining silver stained regions are probably due to the heterochromatin with some affinity to the Ag-staining. Phylogenetic analysis based on partial cytochrome b sequence revealed that L. mystacinus forms a basal branch, so that the presence of multiple NORs in pairs 4 and 8 in this species indicates an autapomorphy.

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Paratelmatobius and Scythrophrys are leptodactylid frogs endemic to the Brazilian Atlantic forest and their close phylogenetic relationship was recently inferred in an analysis that included Paratelmatobius sp. and S. sawayae. To investigate the interspecific relationships among Paratelmatobius and Scythrophrys species, we analyzed a mitochondrial region (approximately 2.4 kb) that included the ribosomal genes 12S and 16S and the tRNAval in representatives of all known localities of these genera and in 54 other species. Maximum parsimony inferences were done using PAUP* and support for the clades was evaluated by bootstrapping. A cytogenetic analysis using Giemsa staining, C-banding and silver staining was also done for those populations of Paratelmatobius not included in previous cytogenetic studies of this genus in order to assess their karyotype differentiation. Our results suggested Paratelmatobius and Scythrophrys formed a clade strongly supported by bootstrapping, which corroborated their very close phylogenetic relationship. Among the Paratelmatobius species, two clades were identified and corroborated the groups P. mantiqueira and P. cardosoi previously proposed based on morphological characters. The karyotypes of Paratelmatobius sp. 2 and Paratelmatobius sp. 3 described here had diploid chromosome number 2n = 24 and showed many similarities with karyotypes of other Paratelmatobius representatives. The cytogenetic data and the phylogenetic analysis allowed the proposal/corroboration of several hypotheses for the karyotype differentiation within Paratelmatobius and Scythrophrys. Namely the telocentric pair No. 4 represented a synapomorphy of P. cardosoi and Paratelmatobius sp. 2, while chromosome pair No. 5 with interstitial C-bands could be interpreted as a synapomorphy of the P. cardosoi group. The NOR-bearing chromosome No. 10 in the karyotype of P. poecilogaster was considered homeologous to chromosome No. 10 in the karyotype of Scythrophrys sp., chromosome No. 9 in the karyotype of Paratelmatobius sp. 1, chromosome No. 8 in the karyotypes of Paratelmatobius sp. 2 and of Paratelmatobius sp. 3, and chromosome No. 7 in the karyotype of P. cardosoi. A hypothesis for the evolutionary divergence of these NOR-bearing chromosomes, which probably involved events like gain in heteochromatin, was proposed.

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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

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Haematobia irritans is a hematophagous parasite of cattle that causes significant economic losses in many parts of the world, including Brazil. In the present work, one American and four Brazilian populations of this species were studied by Random Amplified Polymorpht DNA (RAPD) to assess basically genetic variability within and between populations. Ten different decamer random primers were employed in the genomic DNA amplification, yielding 117 fragments in the five H.. irritans populations. In Drosophila prosaltans, used as an outgroup, 81 fragments were produced. Forty-three of these fragments were shared by both species. Among the H. irritans samples, that from Rio Branco (Acre State, Brazil) produced the smallest numbers of fragments and polymorphic bands. This high genetic homogenity may be ascribed to its geographic origin (in the Northwest of Brazil), which causes high isolation and low gene flow, unlike the other Brazilian populations, from the South Central region, in which cattle trade is very intensive. Marker fragments (exclusive bands) detected in every sample enabled the population origin to be characterized, but they are also potentially useful for further approaches such as the putative origin of Brazilian populations from North America. Similarity indices [Nei & Li, 1979, Proc. Natl. Acad. Sci. USA 76: 5269-5273] and phylogenetic trees, rooted by using the outgroup and produced by the Phylogenetic Analysis using Parsimony (PAUP 4.0-Swofford, 2001) program showed the closest relationships between flies from Sao Jose do Rio Preto and Turiuba (both from São Paulo State, Brazil) while flies from the geographically distant Rio Branco showed the greatest differentiation relative to the others.

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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

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The present work describes the identification and characterization of a potyvirus isolated from siratro (Macroptilium atropurpureum Urb.) in the north-west region of the State of Sdo Paulo, Brazil. The virus was transmitted by mechanical inoculation. Its host range was restricted mainly to members of the Fabaceae. A cDNA fragment of about 930 bp was amplified by RT/PCR, cloned and sequenced. The fragment, which included the coat protein gene, had amino acid identity percentages between 88 and 98% with isolates of Bean common mosaic virus (BCMV). Phylogenetic analysis grouped the. siratro potyvirus and BCMV isolates in 99% of the replicates, including Azuki mosaic virus, Dendrobium mosaic virus, Blackeye cowpea mosaic virus and Peanut stripe virus, which have been classified as BCMV strains. This is the first citation on the presence of BCMV in siratro plants in Brazil.

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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)