Although natural populations of drosophilid flies have been the subject of ecological studies, the population ecology of these insects in the tropics is still poorly known. This paper discusses aspects of the relationship between drosophilids and their environment, based on 28 monthly collections made in two contrasting vegetations of the Brazilian Cerrado biome: gallery forest and savanna. Exotic species were found in both types of environment; but 14 of the 30 captured Neotropical species occurred exclusively in the gallery forests, probably because of their climatic stability and greater environmental heterogeneity. Even though some endemic species were more abundant in the dry and cold months, most populations exhibited peaks of abundance in the wet season. The species diversity indexes (H ′ and D), higher in the dry season, were probably affected by increased evenness at this time of year, when the populations of practically all the species are greatly reduced. As species richness in the savanna vegetation clearly decreased in the dry season, increasing again in the wet season, it is suggested that some drosophilids migrate to the forests when climatic conditions are too stressful in the savannas.

Evolutionary Biology integrates several disciplines of Biology in a complex and interactive manner, where a deep understanding of the subject demands knowledge in diverse areas. Since this knowledge is often inaccessible to the majority of specialized professionals, including the teachers, we present some reflections in order to stimulate discussions aimed at the improvement of the conditions of education in this area. We examine the profile of evolutionary teaching in Brazil, based on questionnaires distributed to teachers in Secondary Education in the Federal District, on data provided by the "National Institute for Educational Studies and Research", and on information collected from teachers working in various regions of this country. Issues related to biological misconceptions, curriculum and didactic material are discussed, and some proposals are presented with the objective of aiding discussions aimed at the improvement of the teaching of evolutionary biology.

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Modern environmental destruction through human action has had a big impact on biological diversity. In the Brazilian Cerrado, the second largest South American biome, more than 60% of the native vegetation has been devastated mainly due to anthropic activities. One of the consequences of these activities is the distinct dispersion patterns of endemic and colonizer species in urban environments. In this report we assess the colonizing potential of drosophilids in environments with different grades of urbanization, defined according to the vegetation cover, edifications and demographic density. We performed 12 monthly collections in the city of Brası´lia, the capital of Brazil, which is located in the core region of the Cerrado. Although we identified 16 species, 90% of the 22,509 captured specimens were Zaprionus indianus, a species recently introduced in Brazil, and the cosmopolitan D. simulans. We captured all the exotic species that occur in the Biome, with the exception of D. kikkawai, but only 8 from the 25 endemic species that occur in natural sites around Brası´lia. The abundance of four endemic species (D. nebulosa, D. sturtevanti, D. cardini and D. prosaltans) decreased as the grade of urbanization increased. D. immigrans, an exotic species, showed the opposite pattern. We concluded that most endemic species of Drosophilidae are not able to colonize the new environment represented by the city, and that some species of this family may detect not only environmental alteration, by their presence or absence, but also the grade of environmental disturbance, by their relative abundance.

Although predictions of potential distributions of invasive species often assume niche conservatism, recent analyses suggest that niche shifts can also occur. Thus, further studies are necessary to provide a better understanding of niche dynamics and to predict geographic distribution in invaded areas. The present study investigated the niche shift hypothesis at a broad biogeographical scale, using the comprehensive distribution of the invasive species Zaprionus indianus in its native (Africa) and invaded (America and India) ranges. Z. indianus is a very successful invasive species that presents high adaptive flexibility and extreme physiological tolerance. To investigate whether Z. indianus changed its climatic niche from Africa to America and India, multivariate analyses, as well as ecological niche modeling procedures (GARP, MAXENT and Mahalanobis distances), were used. Multivariate analyses showed that the niche spaces of Z. indianus in Africa, India and the Americas were significantly different (Wilks' k from a Multivariate Analysis of Variance, MANO-VA = 0.115; P \ 0.0001). Out of 108 occurrences in America, only 11 (ca 10%) were classified, by Canonical Variate Analysis scores, as belonging to its original range in Africa, whereas only 5% of the 39 occurrences in India were classified as belonging to Z. indianus' original range. Consensus results from MAXENT, GARP and Mahalanobis distances correctly predicted only 27% of the occurrences in India and 85% of occurrences in America. Thus, all analyses showed that Zaprionus indianus quickly expanded ranges into different environments in the invaded areas, suggesting climatic niche shifts, primarily in India.