Research Article

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The evolution of the metazoa has been characterized by gene redundancy, generated by polyploidy, tandem duplication and retrotransposition. Polyploidy can be detected by looking for duplicated chromosomes or segments of orthologous chromosomes in post-polyploid animals. It has been proposed that the evolutionary role of polyploidy is to provide extra-copies of genes, whose subsequent ... more

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Polyploidy is a prominent and significant force in plant evolution, taking place since ancient times and continuing until today. Recent cytogenetic studies in the genus Brachiaria using germplasm collected from wild African savannas in the 1980s revealed that most species and accessions within species are polyploid. Diploid, tetraploid, and pentaploid accessions have been found. ... more

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R.A.Bernardo Filho; A.C.C. Santos; F.H.D. Souza; J.F.M. Valls; M.S. Pagliarini
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Evolution; Future selection; Immune system; Lamarck & Darwin legacies; Somatic selection
H. Hoenigsberg
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Cell biology conservation; Darwinian evolution; Evolution; Prokaryotes

Our theory is embarrassingly simple. What made today’s prokaryotes and modern cyanobacteria so robust is the fact that in their origin, back in the Archean (3 billion years ago), selection did not play a central role in evolution, it had only a transitory role. Asexual reproduction, mutation, drift and sampling variance in local demes were more important especially when they were ... more

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We examined the variation in mitochondrial DNA by sequencing the D-loop region in wild and domestic (large-white breed) pigs, in hybrids between domestic and wild pigs, and in Monteiro pigs. A D-loop fragment of approximately 330 bp was amplified by PCR. Sequencing of DNA amplicons identified haplotypes previously described as European and Asian types. Monteiro pigs and wild pigs had ... more

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A total of 98 Manihot species have been recognized in the genus. All of them are native to the tropics of the New World, particularly Brazil and Mexico. The cultigen, Manihot esculenta Crantz (cassava), grows throughout the lowland tropics. Wild species vary in growth habit from acaulescent or short shrubs to tree-like. Because of their adaptations to different conditions, ... more

N.M.A. Nassar; D.Y.C. Hashimoto; S.D.C. Fernandes
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Ctenomyidae; Cytochrome b; Evolution; Molecular phylogeny

The genus Ctenomys (Rodentia: Ctenomyidae) shows several taxonomic inconsistencies. In this study, we used an integrative approach including DNA sequences, karyotypes, and geometric morphometrics to evaluate the taxonomic validity of a nominal species, Ctenomys bicolor, which was described based on only one specimen in 1912 by Miranda Ribeiro, and since then neglected. ... more

J.F.B. Stolz; G.L. Gonçalves; L. Leipnitz; T.R.O. Freitas
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45S rDNA; AgNOR-banding; Anura; chromosome; Evolution

Chromosome numbers, morphology, and nucleolus organizer region (NOR) locations are useful cytological characters for taxonomic and evolutionary studies. In this study, we provide the first cytogenetic analysis of Phyllomedusa bahiana and Phasmahyla spectabilis, and report new cytogenetic data on variation in NOR numbers and positions in Phyllomedusa rohdei and ... more

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Evolution; FISH; Neotropical region; Systematic phylogeny

A species complex hypothesis involving Astyanax fasciatus from southern Brazil was tested using 12S mtDNA sequences. Phylogenetic inferences were performed with maximum likelihood, maximum parsimony and Bayesian as phylogenetic methods and Hemigrammus bleheri as the outgroup. Besides 11 sequences from A. fasciatus, the data set was comprised of other partial ... more

D.A. Matoso; M. da Silva; R.F. Artoni; R.A. Torres

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