Navegando por Assunto "Marsupial"

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Acesso aberto (Open Access)
Dieta de Micoureus demerarae (Thomas) (Mammalia, Didelphidae) associada às florestas contíguas de mangue e terra firme em Bragança, Pará, Brasil
(2006-12) FERNANDES, Marcus Emanuel Barroncas; ANDRADE, Fernanda Atanaena Gonçalves de; SILVA JÚNIOR, José de Sousa e
The diet of Micoureus demerarae (Thomas, 1905) was studied in mangrove and terra firme stands by using stomachal and faecal samples. The number of captured individuals was inversely proportional to availability of fruits and insects, being Coleoptera and Hemiptera the most consumed arthropod orders and Passifloraceae and Arecaceae the most ingested fruits. Thus, either fruits variability or their high yield during the dry season seem to explain the increase of captured animals in the terra firme stands, where they originally come from. The food items suggest that this species has an omnivorous diet, independently of the seasonality or distribution of available resources.
Acesso aberto (Open Access)
Diversidade de espécies no complexo Monodelphis brevicaudata (Didelphimorphia:Didelphidae), inferida por dados moleculares e morfológicos
(Universidade Federal do Pará, 2009) PAVAN, Silvia Eliza D´Oliveira; ROSSI, Rogério Vieira; http://lattes.cnpq.br/0447251112059340
Short‐tailed opossums of the Monodelphis revicaudata complex inhabit northern South America, and comprise three described species ‐ M. brevicaudata, M. glirina, and M. palliolata ‐ and two undescribed forms already recognized in prior studies. Species delimitation based solely on morphological features is difficult, and because of that many nominal taxa have been associated with this species complex, and several taxonomic arrangements have been proposed. Previous molecular phylogenetic studies using specimens of this species complex revealed substantial genetic divergence rates. The present study aims to elucidate the systematics of the M. brevicaudata species complex through the analyses of molecular and morphological characters. We performed phylogenetic analyses on two mitochondrial genes (cyt b and 16S), studied the external and cranial morphology, and investigated whether observed genetic variation is congruent with morphological differences. Our morphological results were generally concordant with the molecular results. We recognize nine species in the species complex. M. brevicaudata, M. palliolata, and M. glirina are considered valid species; M. touan is re‐established from the synonymy of M. brevicaudata and two new species are described and named; the species M. domestica proved to be closely related to specimens of the M. brevicaudata complex, and thus are considered as part of that group; we also recognized two new species without formallly naming them; M. maraxina is considered a synonym of M. glirina. Sexual dimorphism is observed in the species, and in two species males showed skulls significantly larger than females. Major rivers seem to have played an important role in generating genetic differentiation and phylogeographical structure of the species. The phylogeographical pattern suggests at least two diversification centers for the group, one in the Guiana shield, comprising species ranging north of the Amazon river, and another in the Brazilian shield, comprising M. glirina and M. domestica.
Acesso aberto (Open Access)
Estudo da comunidade de pequenos mamíferos não-voadores, sob efeito do fogo e da borda, em área de floresta de transição Amazônia-Cerrado, Querência, MT
(Universidade Federal do Pará, 2008-10-10) SANTOS, Paulo Guilherme Pinheiro dos; OLIVEIRA, Ana Cristina Mendes de; http://lattes.cnpq.br/1199691414821581
The deforestation of the Amazon, caused by farming and agribusiness activities in the northern state of Mato Grosso, has committed Transition Forests Amazon-Savanna, before the biodiversity of these areas is known by researchers. The fauna of small non-flying mammals is part of the little-known groups in the region, and may be suffering impacts of human activities, primarily effect of fire, used for cleaning of pastures and deforestation for the soybean plantations. This study characterized the diversity of small mammals not flying in an area of Amazon forest-savannah transition in the northern state of Mato Grosso and investigated the effect of fire and the effect of edge on this group of fauna. Two areas of 150 hectares were sampled, a preserved and another under impact of fire, with 183 traps of the type live-trap for three years in two season (dry and rainy seasons). The method used was the capture-mark-recapture. The sampling effort was 23,424-traps night. 390 individuals were captured with a successfully capture of 1.66%. A total of 11 species were caught, 6 rodents and 5 marsupials. Hylaeamys megacephalus was the most abundant species. The diversity of small mammals in the study area was more related to the Savanna than Amazon. In relation to fire, the species richness was not statistically different, but the abundance was significantly higher in transects located in an area without fire. Two distinct groups of transects were characteristic depending on the presence or absence of fire based on the composition of small mammals. The abundance of Hylaeamys megacephalus was significantly higher in transects that suffered no impact from fire. Regarding the effect of edge in Area 2, despite the richness of species was not significantly different, the abundance was significantly higher regarding distance from the border. Already in Area 1, nor richness nor abundance was statistically different regarding distance from the edge. This fact could be masked by both the direct and indirect effect of experimental fire on small mammals. When considered together fire and distance from the border, the relationship between them became clearer, since all transects sampled under effect of the fire had minor abundances. The population size of Hylaemys megacephalus was calculated over five seasons (dry and wet) in the area without influence of fire, and the rainy season of 2006 was statistically different peak and the other that growth can be explained by the “Alle effect”. There was no statistically significant differences in the structure of the community of small non-flying mammals between the dry and rainy seasons. This work contributed to the search of mammal knowledge at this region threatened by human pressures.
Acesso aberto (Open Access)
Parâmetros demográficos de Micoureus demerarae (Didelphidae, Marsupialia) em áreas contíguas de manguezal e terra firme, Bragança, Pará, Brasil
(2007-06) ANDRADE, Fernanda Atanaena Gonçalves de; FERNANDES, Marcus Emanuel Barroncas; BRITO, Stélio Ângelo da Costa
This study investigated some aspects of the population dynamics of Micoureus demerarae (Thomas, 1905), such as: density, recruitment, and survivorship in two contiguous ecosystems, mangal and terra firme at the Fazenda das Salinas in the northeast of the state of Pará. One transect in each system was used for fieldwork. Data collection was carried out from November 2002 to September 2003. The following population parameters were estimated: density, recruitment, and survivorship. The results defined an open population with an even distribution for individuals from mangal and a clumped one for individuals from terra firme, and the evident seasonality with higher proportion of males in the terra firme. The reproductive period was the most important parameter to the population fluctuation in the beginning of the dry season. The environmental impacts over the population dynamics parameters of M. demerarae seem to be determinant for the maintenance of these populations.