Redescription of Sibling Species of Rhinoleucophenga (Diptera: Drosophilidae): R. brasiliensis and R. fluminensis.

Rhinoleucophenga Hendel comprises an unusual Drosophilidae (Diptera) genus with predaceous larvae, currently compounded by 29 nominal species with New World distribution. In the present study, Rhinoleucophenga brasiliensis (Costa Lima) and R. fluminensis (Costa Lima) are redescribed. These two species are commonly misidentified in Drosophilidae species inventories, mainly by the few morphological character details presented in the original taxonomic description. Thus, by the morphological review performed here, lectotype and paralectotypes designed to R. brasiliensis and R. fluminensis, as well as new morphological characters, drawings and photos (for the first time) are presented in order to avoid further taxonomic mistakes with those referred sibling species of Rhinoleucophenga.

Contributions of Dryland Forest (Caatinga) to Species Composition, Richness and Diversity of Drosophilidae.

In this study, semi-arid environments were tested to see if they support insect diversity. This was evaluated through the structure of the composition of assemblies of drosophilids in three conservation units placed in three different ecoregions in the dryland forests, Caatinga. This is a unique biome in northeast Brazil, comprising approximately 10% of the country. Species richness was investigated over 2 years during a prolonged drought, considered the worst affliction the Caatinga ecosystem had experienced in the last 50 years. Alpha diversity indices and the ecological similarity between the samples were calculated to determine how the environments drive the composition of Drosophilidae in such semi-arid places. A total of 7352 specimens were sampled. They were classified into 20 species belonging to four genera: Drosophila, Rhinoleucophenga, Scaptodrosophila, and Zaprionus. Drosophila nebulosa Sturtevant (44.5%) and Drosophila cardini Sturtevant (12.5%) were the most abundant species. The occurrences and abundances of all the species differed greatly between sites. These results and other ecological analyses indicate that although placed in the same biome, there are great variability in the drosophilid species and abundance among the three protected and conserved dryland environments.

Environmental determinants on the assemblage structure of Drosophilidae flies in a temperate-subtropical region.

The species composition and the relative abundance of species in an insect community can vary in time and space for many reasons, including climatic variables and habitat preferences. Drosophilids were collected each quarter from April 2011 to April 2012 (five collections in all) in a natural area of the Pampa biome, considering three environments: open field, forest edge and the interior of forest patches. Kruskal-Wallis and chi-square tests were used to examine the effects of temporal and spatial components on the drosophilid assemblage. Four diversity measures: S obs , S rar , H' and E var were used to evaluate the community structure. A total of 7164 drosophilids belonging to 51 species were collected. The interaction of species in each environment varied among sampling periods. The abundance of both Neotropical and exotic species was affected by temporal and spatial components. The species of the D. repleta group were predominantly more abundant in the open field, but they migrated to the forest patches during periods of thermal stress. Generally, diversity was greatest in the interior of forest patches. Nevertheless, temporal components appear to be the predominant environmental determinant of the characteristics of the drosophilid community of the Pampas. Furthermore, the forest patches appear to act as a center of recolonization, reinforcing their importance in the maintenance of biodiversity in the Pampas; this function will be even more important in the future, when the temperatures will, most likely, be higher.

Population dynamics of drosophilids in the pampa biome in response to temperature.

Environmental variables such as temperature and rainfall can directly affect the community structure of dipterans. Seasonal oscillations in the abundance of species of Drosophilidae reflect differences in how tolerant populations are to climatic conditions. Over a period of 14 months, we collected samples in two habitats in the Pampa biome in the municipality of São Luiz Gonzaga, state of Rio Grande do Sul, Brazil (28°24'28″S, 54°57'39″W). The influence of environmental variables on populations of Drosophilidae was evaluated for both collecting sites by using correlation analysis. The results suggested a negative correlation between the abundances of Drosophila cardinoides Dobzhansky & Pavan, Drosophila maculifrons Duda, Drosophila melanogaster Meigen, Drosophila nigricruria Patterson & Mainland, and Zygothrica vittimaculosa Burla with temperature, which is reflected in the distribution of these species within Brazil. Our findings are important for characterizing and preserving biodiversity in this almost-unknown biome in southern Brazil given the current climate change scenario.

Ultrastructure and morphogenesis of the wing scales in Heliconius erato phyllis (Lepidoptera: Nymphalidae): what silvery/brownish surfaces can tell us about the development of color patterning?

Usually the literature on Heliconius show three types of scales, classified based on the correlation between color and ultrastructure: type I - white and yellow, type II - black, and type III - orange and red. The ultrastructure of the scales located at the silvery/brownish surfaces of males/females is for the first time described in this paper. Besides, we describe the ontogeny of pigmentation, the scale morphogenesis and the maturation timing of scales fated to different colors in Heliconius erato phyllis. The silvery/brownish surfaces showed ultrastructurally similar scales to the type I, II and III. The ontogeny of pigmentation follows the sequence red, black, silvery/brownish and yellow. The maturation of yellow-fated scales, however, occurred simultaneously with the red-fated scales, before the pigmentation becomes visible. In spite of the scales at the silvery/brownish surfaces being ultrastructurally similar to the yellow, red and black scales, they mature after them; this suggests that the maturation timing does not show a relationship with the scale ultrastructure, with the deposition timing of the yellow pigment. The analysis of H. erato phyllis scale morphogenesis, as well as the scales ultrastructure and maturation timing, provided new findings into the developmental architecture of color pattern in Heliconius.

Drosophilid assemblages at different urbanization levels in the city of Porto Alegre, state of Rio Grande do Sul, southern Brazil.

The present study analyzed the drosophilid assemblages in different levels of urbanization in the city of Porto Alegre, Rio Grande do Sul, Brazil. Collections were carried out in 2008 in three different environments: a highly urbanized area-"Jardim Botânico," a forested area with intermediary urbanization-"Parque Gabriel Knijnik," and in a relatively well-preserved forested area, although threatened by the urban growth-"Morro Santana." In Jardim Botânico, 36 species belonging to four genera were found, with high abundance of exotic species as Drosophila simulans Sturtevant and Zaprionus indianus (Gupta). In Parque Gabriel Knijnik, 33 species that belonged to four genera were found, with higher abundances of native species belonging to the Drosophila tripunctata species group and Drosophila willistoni species subgroup, and lower abundance of exotic species. As for Morro Santana, 32 species and three genera were found, with higher abundances of native groups, low representativeness of exotic species, and absence of Zaprionus indianus. The analysis of the Jaccard index showed higher similarity in the species composition between samples collected in summer and autumn, and between samples collected in winter and spring. On the other hand, the Morisita index differentiated Jardim Botânico from the other two studied sites. Our results show that Morro Santana is an important area of native biodiversity, reinforcing, therefore, the inclusion of this area in the project for the creation of an ecological corridor as proposed by the Ministry of the Environment of Brazil.

Courtship behavior of Zaprionus indianus (Gupta) (Diptera: Drosophilidae) from populations colonizing South America.

We describe for the first time the sexual behavior and the courtship song of males of the African fly Zaprionus indianus (Gupta), a recent invader of South America. The male courtship song is formed by monocyclic pulses and the courtship behavior is simple when compared to that of species of Drosophila. Two interpulse interval (IPI) distributions were observed: pre-mounting and mounting. No significant difference was observed between the pre-mounting IPIs of males that descended from three geographical populations from South America. We also observed the songs produced by females and the homosexual behavior exhibited by males. A sequence of bursts is produced by females as a refusal signal against males, while males emit a characteristic song that identifies sex genus, which differs from the courtship song. The short courtship and mating latencies recorded reveal vigorous males and receptive females, respectively.

The copia retrotransposon and horizontal transfer in Drosophila willistoni.

The copia element is a retrotransposon that is hypothesized to have been horizontally transferred from Drosophila melanogaster to some populations of Drosophila willistoni in Florida. Here we have used PCR and Southern blots to screen for sequences similar to copia element in South American populations of D. willistoni, as well as in strains previously shown to be carriers of the element. We have not found the canonical copia element in any of these populations. Unlike the P element, which invaded the D. melanogaster genome from D. willistoni and quickly spread worldwide, the canonical copia element appears to have transferred in the opposite direction and has not spread. This may be explained by differences in the requirements for transposition and in the host control of transposition.

Taxonomic boundaries, phylogenetic relationships and biogeography of the Drosophila willistoni subgroup (Diptera: Drosophilidae).

The Drosophila willistoni subgroup represents a complex with varying taxonomic levels. It encompasses D. willistoni and its five sibling species: D. equinoxialis, D. insularis, D. paulistorum, D. pavlovskiana and D. tropicalis. Of these, D. equinoxialis, D. tropicalis and D. willistoni present differentiation at subspecific level, whereas D. paulistorum represents a superspecies, formed by six semispecies. Despite this taxonomic and evolutionary complexity, many of these semi and subspecific taxa have not yet had their phylogenetic status tested in an explicitly molecular study. Aiming to contribute to the understanding of the evolution of this challenging group, we analyzed nucleotide sequences from two mitochondrial and four nuclear datasets, both individually and simultaneously, through different phylogenetic methods. High levels of incongruence were detected among partitions, especially concerning the mitochondrial sequences. As this incongruence was found to be statistically significant and robust to the use of different models and approaches, and basically restricted to mitochondrial loci, we suggest that it may stem mainly from hybridization-mediated asymmetrical introgression. Despite this, our nuclear data finally led to a phylogenetic hypothesis which further refines several aspects related to the willistoni subgroup phylogeny. In this respect, D. insularis, D. tropicalis, D. willistoni and D. equinoxialis successively branched off from the willistoni subgroup main stem, which recently subdivided to produce D. paulistorum and D. pavlovskiana. As regards the semispecies evolution, we found evidence of a recent diversification, which highly influenced the obtained results due to the associated small levels of genetic differentiation, further worsened by the possibly associated incompletely sorted ancestral polymorphisms and by the possibility of introgression. This study also raises the question of whether these semispecies are monophyletic at all. This reasoning is particularly interesting when one considers that similar levels of reproductive isolation could be attained through infection with different Wolbachia strains.

Mobilization of a hobo-related sequence in the genome of Drosophila simulans.

The hobo transposable element can occur under three forms in the Drosophila genome: as a complete element (also called canonical), as internally deleted copies, or as hobo-related sequences (relics). Some evidence indicated that canonical elements and internally deleted copies are recent acquisitions of Drosophila genomes, while the "relics" are old components, normally degenerated and immobile. Here we present the characterization of a hobo-related sequence, found in the genome of a hypermutable strain of D. simulans, which insertion into the white locus raised a de novo white mutation. It is a shorter hobo related element presenting, overall, roughly 18% of divergence at the DNA level from the canonical hobo, with many indels that make clear this element is defective. However, its ITRs and flanking regions are extremely conserved. This is the first hobo "relic" showed to be mobilizable. We suggest, and point up some evidences, toward the idea that this sequence could have been mobilized by the canonical element. The presence of a similar "relic" element in D. sechellia allows us to suggest that these elements have been maintained mobilizable since the time of divergence between these species.

Mating activity of yellow and sepia Drosophila willistoni mutants.

By analyzing the mating activity of newly isolated yellow and sepia mutants of Drosophila willistoni no difference in behavior between sepia and wild-type flies were observed, whereas yellow males were less successful than wild-type males when competing for females. These results are in agreement with those reported for other Drosophila species. D. willistoni was different in the 'females-competing' crosses because wild-type males mated more frequently with wild-type females whereas yellow males mated successfully with both phenotypes. These results indicate the complexity of the courtship behavior in D. willistoni and provide data for comparative and evolutionary research into the genus.

Differential gene activation in Drosophila melanogaster populations selected for developmental rate

Foi estudado no estágio de prepupa de zero hora, o padräo de puffs de populaçöes de Drosophila melanogaster submetidas por muitas geraçöes de seleçäo para diferenças na velocidade de desenvolvimento. Puffs com valores médios menores foram encontrados na populaçäo selecionada para velocidade lenta quando comparada com os das populaçöes controle e selecionada para desenvolvimento rápido. Com o balanço entre hormônio juvenil e ecdisona é o fator determinante da velocidade do desenvolvimento e como a ecdisona é responsável pelo início do ciclo de puffs (como por exemplo 47EF, 63E, 71CE e 82EF), nós sugerimos que diferenças na regulaçäo desses hormônios possam explicar as variaçöes nos padröes de puffs observadas aqui. Por outro lado, o padräo de puffs de hibridos entre estas populaçöes sugere que o controle de alguns puffs, como 66B, pode ser devido a um regulador em cis