Navegando por Assunto "Saguinus"

Agora exibindo 1 - 5 de 5

Acesso aberto (Open Access)
A comparative study of eleven protein systems in tamarins, genus Saguinus (Platyrrhini, Callitrichinae)
(1997-03) MEIRELES, Carla Maria Marques; SAMPAIO, Maria Iracilda da Cunha; SCHNEIDER, Horacio; FERRARI, Stephen Francis; COIMBRA-FILHO, Adelmar Faria; PISSINATTI, Alcides; SCHNEIDER, Maria Paula Cruz
The genetic variability of six tamarin taxa, genus Saguinus, was analyzed comparatively using protein data from eleven systems coded by 15 loci. S. fuscicollis weddelli and S. midas midas were the most polymorphic taxa, and S. bicolor the least. The results of the phylogenetic analyses (UPGMA and neighbor-joining) and the genetic distances between taxa were generally consistent with their geographic and probable phylogenetic relationships. Analyses of the S. bicolor and S. midas populations suggested that they represent no more than three subspecies of a single species, S. midas, with the bicolor forms belonging to a single subspecies, S. midas bicolor. If supported by additional studies, this would have important implications for the conservation of the bicolor form, which is endangered with extinction. The genetic similarity of S. fuscicollis and S. mystax was also consistent with their geographical and morphological proximity, although more data from a larger number of taxa will be required before the taxonomic relationships within the genus can be defined.
Acesso aberto (Open Access)
Cytogenetic study of the genus Saguinus (Callithrichidae, Primates)
(1997-12) DANTAS, Sandra Maria Mendes de Moura; BARROS, Regina Maria de Souza
Eight subspecies from the genus Saguinus (S. fuscicollis fuscicollis, S. fuscicollis weddelli, S. bicolor bicolor, S. bicolor martinsi, S. mystax mystax, S. imperator imperator, S. midas midas, and S. midas niger) were studied. Five of them (S. f. fuscicollis, S. f. weddelli, S. b. martinsi, S. m. mystax and S. i. imperator) had their karyotypes described for the first time. Conventional coloration, banding patterns G, C and NOR, and G/C sequential banding tecniques were used. All samples showed the same diploid number (2n = 46). The patterns of the G, C and NOR bands were very similar with little differences in the quantity and constitutive heterochromatin distribution of the autosomes. Constitutive heterochromatin was observed only in telomeric regions of some chromosomes of S. f. fuscicollis and S. f. weddelli. The X chromosome was the same in all subspecies, but chromosome Y differed in size and morphology. XX/XY chimerism was verified in all subspecies.
Acesso aberto (Open Access)
Mitochondrial DNA-like sequence in the nuclear genome of Saguinus (Callitrichinae, Primates): transfer estimation
(2000-03) SOUZA, Marcelo Nazareno Vallinoto de; SENA, Leonardo dos Santos; SAMPAIO, Maria Iracilda da Cunha; SCHNEIDER, Horacio; SCHNEIDER, Maria Paula Cruz
Mitochondrial DNA-like sequences have been found in the nuclei of a variety of organisms. These nuclear pseudogenes can be used to estimate relative evolutionary rates of mitochondrial genes, and can be used as outgroups in phylogenetic analyses. In this study, mitochondrial sequences with pseudogene-like characteristics, including deletions and/or insertions and stop codons, were found in tamarins (Saguinus spp., Callitrichinae, Primates). Phylogenetic analysis allowed estimation of the timing of the migration of these sequences to the nuclear genome, and also permitted inferences on the phylogeny of the genus. The choice of an inadequate outgroup (Aotus infulatus) prevented a good phylogenetic resolution of the subfamily Callitrichinae. The relatively ancient divergence of the Cebidae (Callitrichinae, Aotinae and Cebinae) may have favored confounding homoplasies.
Acesso aberto (Open Access)
Molecular phylogeny of the genus Saguinus (Platyrrhini, Primates) based on the ND1 mitochondrial gene and implications for conservation
(2005-03) TAGLIARO, Claudia Helena; SCHNEIDER, Horacio; SAMPAIO, Maria Iracilda da Cunha; SCHNEIDER, Maria Paula Cruz; SOUZA, Marcelo Nazareno Vallinoto de; STANHOPE, Michael
The systematics of the subfamily Callitrichinae (Platyrrhini, Primates), a group of small monkeys from South America and Panama, remains an area of considerable discussion despite many investigations, there being continuing controversy over subgeneric taxonomic classifications based on morphological characters. The purpose of our research was to help elucidate the phylogenetic relationships within the monkey genus Saguinus (Callitrichinae) using a molecular approach to discover whether or not the two different sections containing hairy-faced and bare-faced species are monophyletic, whether Saguinus midas midas and Saguinus bicolor are more closely related than are S. midas midas and Saguinus midas niger, and if Saguinus fuscicollis melanoleucus and Saguinus fuscicollis weddelli really are different species. We sequenced the 957 bp ND1 mitochondrial gene of 21 Saguinus monkeys (belonging to six species and nine morphotypes) and one Cebus monkey (the outgroup) and constructed phylogenetic trees using maximum parsimony, neighbor joining, and maximum likelihood methods. The phylogenetic trees obtained divided the genus Saguinus into two groups, one containing the small-bodied species S. fuscicollis and the other, the large-bodied species S. mystax, S. leucopus, S. oedipus, S. midas, S. bicolor. The most derived taxa, S. midas and S. bicolor, grouped together, while S. fuscicollis melanoleucus and S. f. weddelli showed divergence values that did not support the division of these morphotypes into subspecies. On the other hand, S. midas individuals showed divergence compatible with the existence of three subspecies, two of them with the same morphotype as the subspecies S. midas niger. The results of our study suggest that there is at least one Saguinus subspecies that has not yet been described and that the conservation status of Saguinus species and subspecies should be carefully revised using modern molecular approaches.
Acesso aberto (Open Access)
Tocantins river as an effective barrier to gene flow in Saguinus niger populations
(2006) SOUZA, Marcelo Nazareno Vallinoto de; SILVA, Juliana Araripe Gomes da; RÊGO, Péricles Sena do; TAGLIARO, Claudia Helena; SAMPAIO, Maria Iracilda da Cunha; SCHNEIDER, Horacio
The Saguinus represent the basal genus of the Callitrichinae subfamily. Traditionally this genus is divided into three groups: Hairy, Mottled and Bare-face, however, molecular data failed to validate these groups as monophyletic units, as well as raised some subspecies to the species status. This is the case of the former subspecies Saguinus midas midas and S. midas niger, which are now considered as different species. In the present study, we sequenced a portion of the D-loop mtDNA region in populations from the East bank of the Xingu and from both banks of the Tocantins river, in order to test the effectiveness of large rivers as barriers to the gene flow in Saguinus. According to our results, the populations from the East and West banks of the Tocantins river are more divergent than true species like S. mystax and S. imperator. The Tocantins river may be acting as a barrier to gene flow, and consequently these very divergent populations may represent distinct taxonomic entities (species?).