Navegando por Orientadores "SCHNEIDER, Horacio"

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Acesso aberto (Open Access)
Análise da variabilidade genética e estudo populacional de Antilophia bokermanni (Aves: Pipridae) com implicações para sua conservação
(Universidade Federal do Pará, 2010) RÊGO, Péricles Sena do; SCHNEIDER, Horacio; http://lattes.cnpq.br/3621033429800270
The Araripe Manakin Antilophia bokermanni (Passeriformes, Pipridae) is the most threatened member of this family, and is classified as “critically endangered”. With an estimated population of only 800 individuals, this species is endemic to a small area (approximately 30 km²) of forest on the slopes of the Araripe Plateau in northeastern Brazil. The urgent need for the implementation of an effective conservation program for the Araripe Manakin has stimulated intensive research into various aspects of its biology. In the present study, we examined sequence variation in segments of the mtDNA and ncDNA in specimens of A. bokermanni and A. galeata. The current analysis provides no evidence for population substructuring nor for a history of population expansion of A. bokermanni. The genetic variability is slightly reduced in comparison with its sister species, but their similarity indicates a relatively recent process of separation, indicated by retention of ancestral polymorphisms (incomplete lineage sorting) all markers. We also did not detect any association between plumage variation and nucleotide variation at MC1R in genus Antilophia. This study represents a contribution of genetics to the Conservation Plan of Araripe Manakin (Antilophia bokermanni).
Acesso aberto (Open Access)
Análises populacionais em Lutjanus purpureus (Poey, 1866) da costa atlântica ocidental a partir de marcadores moleculares
(Universidade Federal do Pará, 2015-03-02) SILVA, Raimundo Darley Figueiredo da; GOMES, Grazielle Fernanda Evangelista; http://lattes.cnpq.br/5740656339448561; SCHNEIDER, Horacio; http://lattes.cnpq.br/3621033429800270
Marine organisms with wide distribution are excellent models for the understanding of historical genetic connectivity patterns. Lutjanus purpureus, or Caribbean snapper, as the species is popularly known, is a marine Teleost belonging to the Family Lutjanidae. The species distribution is from Cuba to the Northeast of Brazil, being often found on rocky and sandy bottoms. It has high economic importance, however there are few studies available on the genetic architecture of the species. Of major goals of this study, the first deals with the development and characterization of the EPIC primers, for population approaches in L. purpureus, and others marine teleosts. The characterization of genomic regions with sufficient polymorphism to population analysis is fundamental for genetic studies with multiple unlinked regions. Were obtained eight primers, and the majority has high levels of genetic variation. EPIC primers have the advantage of being applicable on a wide taxonomic level, thereby these primers were tested and amplified in other taxonomic groups of organisms, so that an indication can be useful in various approaches to intraspecific groups of marine fish. The second main objective was to evaluate issues of genetic diversity, demographics and historical genetic connectivity for L. purpureus using multiple loci (mitochondrial and nuclear DNA). It was found high levels of genetic diversity, probably related to a high effective size presented by species. The Caribbean snapper apparently shows high levels of genetic homogeneity along of the study area, which is consistent with biological traits of species such as spawning in offshore and larval pelagic development. In relation to aspects of historical demography, a population growth scenario is presented, whose beginning is dated about 170,000 years, this period being congruent with a period of glacial maximum to the region of the western Atlantic.
Acesso aberto (Open Access)
Filogenia e história biogeográfica do grupo Callicebus moloch (Primates, Pitheciidae)
(Universidade Federal do Pará, 2015-01-29) CARNEIRO, Jeferson Costa; SILVA JÚNIOR, José de Sousa e; http://lattes.cnpq.br/4998536658557008; SCHNEIDER, Horacio; http://lattes.cnpq.br/3621033429800270
Callicebus is a genus of Neotropical primate of the family Pitheciidae. Thirty-two species are currently recognized. They are classified in two subgenera, Torquatus and Callicebus, and five species groups: C. torquatus, C. moloch, C. cupreus, C. donacophilus and C. personatus. The arrangement of subgenera and groups is based on morphology and geographic distributions. The first section, we is introduction to the taxonomy of Callicebus. In the second section, I present an article for submission to the jounrla Primates concerning the chapter presence or absence of a molecular region known as an Alu element. An Alu element is a transposon in the genome of primates Because of this particular characteristic of Alu insertion, I discovered that the C. moloch and C. cupreus groups are closely related and that C. torquatus is the basal group in the genus. In the third section , from a multilocus approach I investigated the phylogenetic relationships of the C. moloch group and the time of diversification between the species, in order to test the hypothesis of formation of the Amazon River basin during the Plio-Pleistocene. Our results support the hypothesis of origin of Amazonian rivers in the last 3 Ma. However, not all diversification events in Callicebus can be explained by the theory of rivers. the results also indicate that the different species groups are derived from a radiation in the Amazonian region at different times during the upper Miocene. The phylogenetic analysis identified a number of potentioal taxa that a number of taxa which the current knowledge of species diversity in Callicebus is underestimated, and that recently diversified species are taxonomically neglected.
Acesso aberto (Open Access)
Filogenia molecular dos xenarthra (Mammalia): análise do grupo cingulata a partir de sequências nucleotídicas do gene mitocondrial rRNA 16S
(Universidade Federal do Pará, 2007-05-01) PAMPLONA NETO, Christóvam; SCHNEIDER, Horacio; http://lattes.cnpq.br/3621033429800270
Xenarthra is the group of mammals which include armadillos, anteaters and sloths. South America was the landscape of their natural history. Only toward the end of the Cenozoic they spread from South America to Cen-tral America and, in decreasing variety, farther in North America and to some of the West Indian islands. The 31 extant species are described within xenarthran lineage. They are distributed in 13 genera, four families (Brady-podidae, Magelonychidae, Myrmecophagidae and Dasypodidae) and two or-ders orders (Cingulata and Pilosa). The phylogeny of this group has been addressed by multiple researchers using both morphological and molecular data sets. Through phylogenetic analyses of protein-coding nuclear genes and mitochondrial genes, Delsuc et al. (2003) found evidence for the hy-pothesis of monophyly of the subfamilies Dasypodinae, Tolypeutinae and Euphactinae within the family Dasypodidae. They had generated the fol-lowing tree: (((Bradypus, Choloepus)100, ((Myrmecophaga, Tamandua)100, Cyclopes)100), ((D. kappleri, D. novemcinctus)100, (Tolypeutes, (Priodontes, Cabassous)54)100, (Zaedyus, (Euphractus, Chaetophractus)60)100)). Gaudin (2005) presented a work that reviewed and extended the morphological data available, concluding that the extant armadillos are divided in two groups, a basal group (Dasypodinae) and another more derivative (Euphractinae), in accordance with the following arrangement: (Bradypus, Tamandua), (Dasy-pus, (Priodontes, (Cabassous, (Tolypeutes, (Euphractus, Chaetophractus, (Za-edyus, Ch/amyphorus)42)36)72)72)40)85). In the work described in this dis-sertation, we sequenced part of the 16S rRNA mitochondrial gene from 12 extant taxa of Xenarthra to perform phylogeny analysis based on maximum-likelihood. Our results are presented analysing the 16S gene data alone, an concatenated with the dataset of Delsuc et al. (2003): (Bradypus, (Choloe-pus, ((Cyclopes, (Myrmecophaga, Tamandua)100)100, (Dasypus, (((Cabas-sous, Priodontes)68, Tolypeutes)100,((Chaetophractus, Euphractus)65, Za-edyus)100)100)100)100)100). Results were similar to those of previous stu-dies. However, an improvement in bootstrap values of certain branches could be noticed. We believe that Transposable Elements (UNES) are the molecular markers more adjusted to confirm uncertain arrangements sugges-ted by phylogenetic analyses mitocondrials and nuclear genes.
Acesso aberto (Open Access)
Genética de populações de pirarucus (Arapaima gigas) da Reserva Mamirauá e considerações sobre estrutura genética para a espécie
(Universidade Federal do Pará, 2008-10-24) SILVA, Juliana Araripe Gomes da; SCHNEIDER, Horacio; http://lattes.cnpq.br/3621033429800270
The pirarucu (Arapaima gigas) is an important fishing resource in the Amazon which has been exploited since the XIXth century. There are indications of a decrease in population size in some parts of its distribution. Management is one of the strategies adopted to maintain fishing activity associated to the conservation of the species. We evaluate aspects of pirarucu populations in two places in the Mamirauá Reserve (Jarauá and Maraã), and compare these populations with those of Santarém and Tucuruí, analyzing their genetic variability and structure. In order to achieve this, seven microsatellite loci were genotyped for 463 pirarucus from Mamirauá Reserve collected along five years. Our results show a greater genetic diversity for this population in comparison to populations from Santarém and Tucuruí. Analyses indicate that management has been ecologically efficient, since there were no significant change in genetic diversity over the five years of study. Lateral migration, associated with a possible standardized return to lakes without spacial fidelity seems to have great importance for local genetic admixture. However, this admixture is limited in space, with a small degree of genetic differentiation seem between pirarucus from Jarauá and Maraã. When including more distant localities to the analysis, the differentiation is greater though geographic distance cannot explain all of this. We believe that a population decline in intermediate localities, probably caused by overexploiting is influencing the connectivity among the localities studied.
Acesso aberto (Open Access)
Variação geográfica em Schizodon dissimilis (Garman, 1890) e diversidade genética e filogeográfica do grupo Schizodon fasciatus sensu lato (Characiformes: Anostomidae)
(Universidade Federal do Pará, 2013) ABREU, João Marcelo da Silva; SCHNEIDER, Horacio; http://lattes.cnpq.br/3621033429800270