Descrição do comportamento de corte em duas espécies do grupo Cardini de Drosophila (Diptera: Drosophilidae)

TCC(graduação) - Universidade Federal de Santa Catarina. Centro de Ciências Biológicas. Biologia.Foram observados 200 casais de Drosophila cardinoides e 200 casais de Drosophila polymorpha a fim de descrever o comportamento de corte destas espécies. A análise foi feita pela observação dos casais por um tempo mínimo de 50 minutos, ou até que o casal terminasse a cópula. Ambas as espécies demonstraram ser extremamente similares e seguiram os comportamentos já descritos para o gênero. Esta observação permitiu também determinar os tempos médios de latência, corte e cópula em 4,5 min, 12 min e 18 min para D. cardinoides e 3,5 min, 17 min e 26 min para D. polymorpha. A avaliação do comportamento de corte como barreira reprodutiva em Drosophila já foi bastante estudada dentre as espécies do grupo melanogaster. Estes dados foram importantes para o desenvolvimento desta área, mas não exprimem necessariamente toda a variação encontrada no gênero. Trabalhos feitos com espécies do grupo cardini sobre hibridização exploraram apenas as questões associadas a morfologia das moscas e negligenciam outras barreiras reprodutivas como, por exemplo, o comportamento. As observações feitas neste trabalho sugerem que a corte não deva ser uma barreira reprodutiva importante entre estas espécies. Pois, além das já conhecidas semelhanças morfológicas, estas espécies apresentam muitas semelhanças comportamentais na corte. Dentre as variações observadas na corte das espécies de Drosophila, uma das principais é a forma de vibração das asas. Os sons desta vibração são produzidos por complexos movimentos das asas associados a forma da mesma. A covariação entre a forma da asa e o sucesso do acasalamento tem sido descrito para várias espécies de Drosophila. Por isso, dados da morfometria geométrica das asas contribuem muito para o entendimento de como variações na forma das asas influenciam no acasalamento e o sucesso reprodutivo dos indivíduos. As correlações entre tamanho macho/fêmea de casais com e sem sucesso na copula de D. cardinoides e D. polymorpha não foram significativas. Do mesmo modo, não há diferença no tamanho médio entre os machos que conseguiram ou não copular. Tais dados levam a pensar que a relação entre o tamanho do corpo e o sucesso masculino é complexa e pode não ser tão forte como pensado inicialmente, sugerindo que a seleção sexual direcional para aumento do tamanho do corpo masculino não é universal em Drosophila.In order to describe the courtship behavior of Drosophila cardinoides and D. polymorpha, 200 couples of each species were observed. The couples were observed for at least 50 minutes, or until the end of copulation. Both species were shown to be extremely similar, following the behavior already described for the genus. This observation also allowed us to determine the average latency, courtship and copulation times, being 4.5 min, 12 min and 18 min, respectively, for D. cardinoides and 3.5 min, 17 min and 26 min for D. polymorpha. The assessment of courtship behavior in Drosophila as a reproductive barrier has been widely studied among the species of the melanogaster group. These data were important for the development in this area, but do not necessarily express the whole range found within the genre. Previous work involving hybridization of species from the cardini group only explored the issues associated with the flies’ morphology and neglected other reproductive barriers such as the behavior. The observations made in this study suggest that the courtship should not be a major reproductive barrier between these species. Therefore, besides the well-known morphological similarities, these species present many behavioral similarities in courtship. A major form of courtship variation observed in Drosophila species is related to the wing fluttering. Complex wing movements associated with its shape are responsible for producing a vibration sound. The covariation between wing shapes and mating success has been reported for various species of Drosophila. Therefore, data from geometric morphometric wings contribute a lot to the understanding as to how variations in wing shape influence the mating and reproductive success of the studied individuals. According to our results, there is no significant correlation between male/female size and success in copulation for D. cardinoides and D. polymorpha. Also, no differences in mean size were observed between copulating and non copulating flies. Such data leads us to assume that the relationship between body size and male success is complex and may not be as strong as originally thought, suggesting that directional sexual selection related to increasing male body size is not universal in Drosophil

DrosoPhyla: Resources for Drosophilid Phylogeny and Systematics.

The vinegar fly Drosophila melanogaster is a pivotal model for invertebrate development, genetics, physiology, neuroscience, and disease. The whole family Drosophilidae, which contains over 4,400 species, offers a plethora of cases for comparative and evolutionary studies. Despite a long history of phylogenetic inference, many relationships remain unresolved among the genera, subgenera, and species groups in the Drosophilidae. To clarify these relationships, we first developed a set of new genomic markers and assembled a multilocus data set of 17 genes from 704 species of Drosophilidae. We then inferred a species tree with highly supported groups for this family. Additionally, we were able to determine the phylogenetic position of some previously unplaced species. These results establish a new framework for investigating the evolution of traits in fruit flies, as well as valuable resources for systematics

A phylogenomic study of Steganinae fruit flies (Diptera: Drosophilidae): strong gene tree heterogeneity and evidence for monophyly

Abstract Background The Drosophilidae family is traditionally divided into two subfamilies: Drosophilinae and Steganinae. This division is based on morphological characters, and the two subfamilies have been treated as monophyletic in most of the literature, but some molecular phylogenies have suggested Steganinae to be paraphyletic. To test the paraphyletic-Steganinae hypothesis, here, we used genomic sequences of eight Drosophilidae (three Steganinae and five Drosophilinae) and two Ephydridae (outgroup) species and inferred the phylogeny for the group based on a dataset of 1,028 orthologous genes present in all species (> 1,000,000 bp). This dataset includes three genera that broke the monophyly of the subfamilies in previous works. To investigate possible biases introduced by small sample sizes and automatic gene annotation, we used the same methods to infer species trees from a set of 10 manually annotated genes that are commonly used in phylogenetics. Results Most of the 1,028 gene trees depicted Steganinae as paraphyletic with distinct topologies, but the most common topology depicted it as monophyletic (43.7% of the gene trees). Despite the high levels of gene tree heterogeneity observed, species tree inference in ASTRAL, in PhyloNet, and with the concatenation approach strongly supported the monophyly of both subfamilies for the 1,028-gene dataset. However, when using the concatenation approach to infer a species tree from the smaller set of 10 genes, we recovered Steganinae as a paraphyletic group. The pattern of gene tree heterogeneity was asymmetrical and thus could not be explained solely by incomplete lineage sorting (ILS). Conclusions Steganinae was clearly a monophyletic group in the dataset that we analyzed. In addition to ILS, gene tree discordance was possibly the result of introgression, suggesting complex branching processes during the early evolution of Drosophilidae with short speciation intervals and gene flow. Our study highlights the importance of genomic data in elucidating contentious phylogenetic relationships and suggests that phylogenetic inference for drosophilids based on small molecular datasets should be performed cautiously. Finally, we suggest an approach for the correction and cleaning of BUSCO-derived genomic datasets that will be useful to other researchers planning to use this tool for phylogenomic studies

An investigation of Y chromosome incorporations in 400 species of Drosophila and related genera.

Y chromosomes are widely believed to evolve from a normal autosome through a process of massive gene loss (with preservation of some male genes), shaped by sex-antagonistic selection and complemented by occasional gains of male-related genes. The net result of these processes is a male-specialized chromosome. This might be expected to be an irreversible process, but it was found in 2005 that the Drosophila pseudoobscura Y chromosome was incorporated into an autosome. Y chromosome incorporations have important consequences: a formerly male-restricted chromosome reverts to autosomal inheritance, and the species may shift from an XY/XX to X0/XX sex-chromosome system. In order to assess the frequency and causes of this phenomenon we searched for Y chromosome incorporations in 400 species from Drosophila and related genera. We found one additional large scale event of Y chromosome incorporation, affecting the whole montium subgroup (40 species in our sample); overall 13% of the sampled species (52/400) have Y incorporations. While previous data indicated that after the Y incorporation the ancestral Y disappeared as a free chromosome, the much larger data set analyzed here indicates that a copy of the Y survived as a free chromosome both in montium and pseudoobscura species, and that the current Y of the pseudoobscura lineage results from a fusion between this free Y and the neoY. The 400 species sample also showed that the previously suggested causal connection between X-autosome fusions and Y incorporations is, at best, weak: the new case of Y incorporation (montium) does not have X-autosome fusion, whereas nine independent cases of X-autosome fusions were not followed by Y incorporations. Y incorporation is an underappreciated mechanism affecting Y chromosome evolution; our results show that at least in Drosophila it plays a relevant role and highlight the need of similar studies in other groups