571 research outputs found

    Chromosome analysis of five Brazilian species of poison frogs (Anura: Dendrobatidae)

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    Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Dendrobatid frogs have undergone an extensive systematic reorganization based on recent molecular findings. The present work describes karyotypes of the Brazilian species Adelphobates castaneoticus, A. quinquevittatus, Ameerega picta, A. galactonotus and Dendrobates tinctorius which were compared to each other and with previously described related species. All karyotypes consisted of 2n = 18 chromosomes, except for A. picta which had 2n = 24. The karyotypes of the Adelphobates and D. tinctorius species were highly similar to each other and to the other 2n = 18 previously studied species, revealing conserved karyotypic characteristics in both genera. In recent phylogenetic studies, all Adelphobates species were grouped in a clade separated from the Dendrobates species. Thus, we hypothesized that their common karyotypic traits may have a distinct origin by chromosome rearrangements and mutations. In A. picta, with 2n = 24, chromosome features of pairs from 1 to 8 are shared with other previously karyotyped species within this genus. Hence, the A. picta data reinforced that the C-banding pattern and the NOR location are species-specific traits in the genus Ameerega. Moreover, the Ameerega monophyletism proposed by previous phylogenetic studies indicates that the karyotypic differences among species in this genus result from a long divergence time.9013137Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)FAPESP [02/12139-9, 05/05132-6]CNPq [300660/2005-7

    Environmental Costs of Government-Sponsored Agrarian Settlements in Brazilian Amazonia

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    Brazil has presided over the most comprehensive agrarian reform frontier colonization program on Earth, in which ~1.2 million settlers have been translocated by successive governments since the 1970's, mostly into forested hinterlands of Brazilian Amazonia. These settlements encompass 5.3% of this ~5 million km2 region, but have contributed with 13.5% of all land conversion into agropastoral land uses. The Brazilian Federal Agrarian Agency (INCRA) has repeatedly claimed that deforestation in these areas largely predates the sanctioned arrival of new settlers. Here, we quantify rates of natural vegetation conversion across 1911 agrarian settlements allocated to 568 Amazonian counties and compare fire incidence and deforestation rates before and after the official occupation of settlements by migrant farmers. The timing and spatial distribution of deforestation and fires in our analysis provides irrefutable chronological and spatially explicit evidence of agropastoral conversion both inside and immediately outside agrarian settlements over the last decade. Deforestation rates are strongly related to local human population density and road access to regional markets. Agrarian settlements consistently accelerated rates of deforestation and fires, compared to neighboring areas outside settlements, but within the same counties. Relocated smallholders allocated to forest areas undoubtedly operate as pivotal agents of deforestation, and most of the forest clearance occurs in the aftermath of government-induced migration

    Student responses to the introduction of case-based learning and practical activities into a theoretical obstetrics and gynaecology teaching programme

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    BACKGROUND: The fourth-year Obstetrics and Gynaecology course at our institution had previously been taught using theory classes alone. A new teaching model was introduced to provide a better link with professional practice. We wished to evaluate the impact of the introduction of case discussions and other practical activities upon students' perceptions of the learning process. METHODS: Small-group discussions of cases and practical activities were introduced for the teaching of a fourth-year class in 2003 (Group II; 113 students). Comparisons were made with the fourth-year class of 2002 (Group I; 108 students), from before the new programme was introduced. Students were asked to rate their satisfaction with various elements of the teaching programme. Statistical differences in their ratings were analysed using the chi-square and Bonferroni tests. RESULTS: Group II gave higher ratings to the clarity of theory classes and lecturers' teaching abilities (p < 0.05) and lecturers' punctuality (p < 0.001) than did Group I. Group II had greater belief that the knowledge assessment tests were useful (p < 0.001) and that their understanding of the subject was good (p < 0.001) than did Group I. Group II gave a higher overall rating to the course (p < 0.05) than did Group I. However, there was no difference in the groups' assessments of the use made of the timetabled hours available for the subject or lecturers' concern for students' learning. CONCLUSIONS: Students were very receptive to the new teaching model
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