O Brasil apresenta alta diversidade de moscas do gêneroDrosophila sendo parte desta riqueza representada pelo grupo cardini. Nós analisamos as flutuações na riqueza e na abundância deste grupo em ambientes que nunca haviam sido estudados na região Nordeste do Brasil. Entre os 28.204 drosofilídeos amostrados, 1.294 pertenceram ao grupo cardini e foram representados por: D. polymorpha, D. cardini,D. neocardini e D. cardinoides. As ocorrências de D. neocardini e D. cardinoides foram registradas pela primeira vez para a Caatinga. Neste bioma, D. cardini destacou-se como a espécie mais abundante e D. polymorpha não foi observada. Na Floresta Atlântica costeira D. cardini não foi registrada, masD. polymorpha foi observada em todas as localidades investigadas. Os manguezais foram os ambientes com a menor abundância e riqueza do grupo cardini. Os Brejos de Altitude apresentaram a maior riqueza deste grupo. Nós sugerimos que a alta abundância deD. polymorpha nos Brejos de Altitude e na Floresta Atlântica Costeira pode refletir a relação histórica entre estes dois ambientes.

Brazil has a high diversity of flies of the genusDrosophila, and part of this richness is represented by thecardini group. We analyzed the fluctuations in the richness and abundance of this group, in environments that had never previously been studied in the northeastern region of Brazil. Among the 28,204 drosophilids sampled, 1,294 belonged to the cardini group and were represented by D. polymorpha, D. cardini, D. neocardini and D. cardinoides. Occurrences ofD. neocardini and D. cardinoides were registered for the first time in the Caatinga. In this biome,D. cardini stood out as having the highest abundance, andD. polymorpha was not observed. In the coastal Atlantic Forest, D. cardini was not registered, but D. polymorpha was found in all the localities investigated. Mangrove swamps were the environment with the lowest abundance and richness of thecardini group. The High-altitude Forest presented the highest richness of this group. We suggest that the high abundance of D. polymorpha in the High-altitude Forest and in the coastal Atlantic Forest may be a reflection of the historical relationship between these two environments.

Drosophila paulistorum Dobzhansky & Pavan, 1949 era considerada inicialmente ausente em ambientes com influência antrópica, mas a detecção dessa espécie na cidade de Porto Alegre, sul do Brasil, em 1985, sugeriu seu potencial de colonização de novos ambientes e levou a fundação de estudos ecológicos com populações desta espécie. Este estudo acompanhou as variações populacionais de D. paulistorum nesta cidade quase 20 anos depois de seu primeiro registro neste local. Coletas de Drosophilidae foram realizadas em pontos com diferentes graus de urbanização e os resultados apontaram para uma expressiva diminuição dos tamanhos populacionais de D. paulistorum em Porto Alegre. Este declínio pode estar relacionado com o crescimento da cidade, assim como com retrações naturais no tamanho das populações devido a mudanças climáticas, tais como, variações nas temperaturas mínimas e máximas como conseqüência do aquecimento global. A introdução recente de Zaprionus indianus Gupta, 1970 também parece contribuir com esse quadro, uma vez que poderia estar modificando as interações entre as espécies nativas.

Drosophila paulistorum Dobzhansky & Pavan, 1949 had initially been considered absent in anthropogenically disturbed environments, but in 1985 the detection of the species in Porto Alegre city, southern Brazil, suggested its potential to colonize new habitats and laid the foundations for ecologic studies on this species' populations. This study followed the variations in D. paulistorum populations in this town almost 20 years after its first local record. Drosophilid specimens were collected in sites with different urbanization grades and the results point to the expressive decline in D. paulistorum populations in Porto Alegre. This decline may be linked to urban growth and to naturally driven population decline, as imputed to climatic changes like variations in maximum and minimum temperatures as a consequence of a global climate warming. Also, the recent introduction of exotic species Zaprionus indianus Gupta, 1970 seems to play a role in this scenario, changing the interactions between native species.

Body color polymorphism of urban populations of cosmopolite fly Drosophila kikkawai Burla, 1954 was investigated in relation to its possible association with environmental temperature. Samples of D. kikkawai were collected in spring, summer, autumn and winter between 1987 to 1988, in zones with different levels of urbanization in the southern Brazilian city of Porto Alegre, Rio Grande do Sul. A clear association was observed between darker flies and both seasons with low temperatures and areas of low urbanization (where temperature is generally lower than in urbanized areas). Results of preliminary laboratory experiments involving six generations of flies grown in chambers at temperatures of 17º and 25ºC confirmed this tendency to a relationship between body color and temperature, with allele frequency of the main gene involved in body pigmentation changing over time.

Chromosomal polymorphism in natural populations of Drosophila willistoni from Uruguay and southern Brazil was investigated in order to understand the genetic characteristics and evolutionary potential of these almost geographically marginal populations. The level of chromosomal polymorphism in samples from Uruguay was higher than in those from the southernmost Brazilian state of Rio Grande do Sul. The increase in the polymorphism of these populations, in which the species almost reaches its southern limit, contradicts the low level of paracentric inversion polymorphism expected under the central-marginal chromosomal polymorphism cline previously reported. The high frequency of some inversions and the presence of unique inversions in samples from Uruguay indicate the uniqueness of these populations.

Disgenesia gonadal dependente de temperatura foi encontrada na prole tanto de cruzamentos intra como interlinhagens, envolvendo duas populações de Drosophila willistoni. Uma delas é derivada de um velho estoque de laboratório e a outra, de uma amostra recentemente coletada de uma população natural. Tal fenômeno não havia ainda sido descrito em D. willistoni e nós sugerimos que a disgenesia gonadal encontrada seja causada por elementos transponíveis, como ocorre em muitas outras espécies de Drosophila.

Temperature-dependent gonadal dysgenesis was shown to occur in the progeny of both inter- and intrastrain crosses involving two populations of Drosophila willistoni, one of which was an old laboratory stock, and the other, freshly collected from a natural population. We propose that the phenomenon observed was caused by the mobilization of transposable elements, as occurs in several other Drosophila species.