Navegando por Assunto "Cricetidae"

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Acesso aberto (Open Access)
Caracterização cromossômica e mapeamento genômico comparativo de Oecomys paricola e Oecomys auyantepui com sondas de Hylaeamys megacephalus (Cricetidae – Sigmodontinae)
(Universidade Federal do Pará, 2015-05-19) ROSA, Celina Coelho da; NAGAMACHI, Cleusa Yoshiko; http://lattes.cnpq.br/8887641213110093
The Order Rodentia represents the largest mammal order, with approximately 42% of species currently known. Rodents have 2,227 species, 468 genera and 33 families recent, the latter being raised to 50 if the extinct families are considered. Their huge variation in morphology, diversity of habitats and climates and food are the causes of this be most numerous and evolutionarily successful among mammalian orders. The Oecomys genus belongs to the subfamily Sigmodontinae (Cricetidae, Rodentia) with approximately 16 described species, distributed in tropical and subtropical forest of Central and South America. Previous cytogenetic studies suggest that Oecomys features large karyotype diversity, with the diploid number ranging from 58 to 86. In this study were analyzed by conventional cytogenetic techniques and multidirectional chromosome painting (using whole chromosome probes of Hylaeamys megacephalus) 18 specimens of Oecomys were analyzed, four were collected in the metropolitan area of Belém, Pará; two in the city of Santa Barbara, Pará; five in the region of Carajás, Pará and 7 in Calha Norte region, Pará. Specimes from Belém Environmental Park had 2n = 72 and FN = 76; specimes from Santa Barbara had 2n = 70 and FN = 74; from Carajás presented 2n = 70 and FN = 72. All this sample was identified as O. paricola. Specimens collected from the Calha Norte region had 2n = 62 and NF = 80 and were identified as O. auyantepui. The cytotypes described for O. paricola showed differences in five HME peaks, indicating 3 associations for this species. O. auyantepui showed five associations. Chromosomal differences found for O. paricola from different geographic regions suggest that these cytotypes belong to cryptic species. We suggest that these populations of O. paricola are a complex of species where the chromosomal differentiation already happened but not the morphological and molecular ones.
Acesso aberto (Open Access)
Edge effects and the impact of wildfires on populations of small non-volant mammals in the forest-savanna transition zone in Southern Amazonia
(2012) FREITAS, Tiago Magalhães da Silva; ALMEIDA, Vitor Hudson da Consolação; VALENTE, Roberta de Melo; MONTAG, Luciano Fogaça de Assis
The impact of fire and edge effects on the community of small non-volant mammals was investigated in transitional Amazon forest within a matrix of soybean plantations. The animals were live trapped on 24 line transects, of which 16 were distributed in unburned areas and 8 in a burned area. A total of 11 species was recorded, including six rodents and five marsupials. The abundance and richness of small mammals appeared to decrease in burned areas, although this impact appeared to mask edge effects. In the absence of fire impacts, a positive relationship was found between mammal abundance and the distance from the forest edge. The impact of the edge effect on the diversity of small mammals appears to be influenced by the type of anthropogenic matrix and the ecological characteristics of the different species.
Acesso aberto (Open Access)
Estudos citogenéticos em roedores do gênero oecomys (rodentia: cricetidae)
(Universidade Federal do Pará, 2011-04-29) ROSA, Celina Coelho da; NAGAMACHI, Cleusa Yoshiko; http://lattes.cnpq.br/8887641213110093
The rodents are one of the most diversified groups of living mammals and also have a large range of ecological adaptations. The rodents, because of yours population characteristics, developed as the most specious group of mammals in Neotropical forests and one of the most interesting for studies of genetic variation and evolution among vertebrates. The genus Oecomys (Sigmodontinae) comprises approximately 16 species that inhabit tropical and subtropical forests in Central and South America. Six of these species are expected to occur in eastern Brasilian Amazon. In literature, the genus Oecomys has a large karyotypic variation, where the diploid number ranges from 58 to 86. In this study specimens of Oecomys paricola Thomas, 1904 from Belém and Marajó Island, northern Brazil, were investigated using cytogenetic, molecular and morphological analyses. Three karyotypes were found, two from Belém (2n=68, FN=72 and 2n=70, FN=76) and a third from Marajó Island (2n=70, FN=72). No molecular or morphological differences were found between the individuals with differing cytotypes from Belém and Marajó Island. Specimens from the Belém City region may represent two cryptic species because two different karyotypes are present in the absence of significant differences in morphology and molecular characteristics. The Marajó Island and Belém populations represent distinct species that have been separated for some time, and are in the process of morphological and molecular differentiation as a consequence of reproductive isolation at the geographic and chromosomal levels.