RESUMO
Genes involved in the reproductive isolation are particularly useful as molecular markers in speciation studies. Lutzomyia longipalpis (Diptera: Psychodidae: Phlebotominae), a putative species complex, is a vector of visceral leishmaniasis in Latin America. We isolated from this species a fragment homologous to cacophony, a Drosophila gene that encodes features of the lovesong, an acoustic signal that is important in the sexual isolation of closely related species and known to vary considerably among L. longipalpis putative siblings species. Using an intron of the sandfly cacophony as a marker, we analyzed the molecular variation and sequence divergence among five populations of L. longipalpis from Brazil, three allopatric (Jacobina, Lapinha and Natal) and two putative sympatric sibling species from the locality of Sobral. A high level of polymorphism was found and analysis of the data indicates that very little gene flow is occurring among the populations of Jacobina, Lapinha, and Natal. A high level of differentiation was also observed between the two putative sympatric species of Sobral, one of which seems to be the same sibling species found in Natal, while the other is somewhat more related to Jacobina and Lapinha. However, the amount of estimated gene flow among the Sobral siblings is about seven times higher than the previously estimated for period, another lovesong gene, perhaps indicating that introgression might be affecting cacophony more than period. The results suggest that L. longipalpis is not a single species in Brazil, but it is yet not clear whether the different populations studied deserve species status rather than representing an incipient speciation process.
Assuntos
Proteínas de Drosophila/genética , Evolução Molecular , Variação Genética , Genética Populacional , Psychodidae/genética , Análise de Variância , Animais , Sequência de Bases , Brasil , Análise por Conglomerados , Primers do DNA , Geografia , Íntrons/genética , Dados de Sequência Molecular , Filogenia , Alinhamento de Sequência , Análise de Sequência de DNA , Especificidade da EspécieRESUMO
The molecular evolution of the clock gene period was studied in Phlebotomine sandflies (Diptera: Psychodidae). Comparison of the synonymous and nonsynonymous substitution rates between sandflies and Drosophila revealed a significantly higher evolutionary rate in the latter in three of the four regions analyzed. The differences in rate were higher in the sequences flanking the Thr-Gly repetitive domain, a region that has expanded in Drosophila but remained stable and short in sandflies, a result consistent with the coevolutionary scenario proposed for this region of the gene. An initial phylogenetic analysis including eight neotropical sandfly species and one from the Old World was also carried out. The results showed that only the subgenus Nyssomyia is well supported by distance (neighbor-joining) and maximum parsimony analysis. The grouping of the other species from the subgenus Lutzomyia and Migonei group shows very low bootstrap values and is not entirely consistent with classical morphological systematics of the genus Lutzomyia.
Assuntos
Evolução Molecular , Genes de Insetos , Proteínas Nucleares/genética , Psychodidae/genética , Sequência de Aminoácidos , Animais , Sequência de Bases , Relógios Biológicos/genética , DNA/genética , Proteínas de Drosophila , Dados de Sequência Molecular , Proteínas Circadianas Period , Filogenia , Homologia de Sequência de Aminoácidos , Homologia de Sequência do Ácido NucleicoRESUMO
Lutzomyia longipalpis (Diptera: Psychodidae: Phlebotominae), the main vector of visceral leishmaniasis in the Americas, is a putative species complex. Molecular polymorphism was characterized in a 266 bp fragment of L. longipalpis homologous to period, a 'speciation gene' from Drosophila. Samples from the Brazilian localities of Jacobina (BA), Lapinha (MG) and Natal (RN) were analysed and the data indicate that the three populations are highly differentiated, with a very low level of gene flow between them. These results are in agreement with published pheromone and copulation song studies that suggest the existence of a sibling species complex in Brazil.
Assuntos
Proteínas Nucleares/genética , Psychodidae/genética , Sequência de Aminoácidos , Animais , Sequência de Bases , Brasil , DNA/química , DNA/genética , Proteínas de Drosophila , Feminino , Variação Genética/genética , Masculino , Dados de Sequência Molecular , Proteínas Nucleares/química , Proteínas Circadianas Period , Filogenia , Reação em Cadeia da Polimerase , Análise de Sequência de DNA , Homologia de Sequência do Ácido NucleicoRESUMO
We present the results of recording male courtship songs of the sandfly Lutzomyia longipalpis. The striking differences in the songs from 3 Brazilian populations of this sandfly with 3 distinct male pheromones support the 3 sibling species previously proposed based on this characteristic.
Assuntos
Copulação/fisiologia , Psychodidae/fisiologia , Vocalização Animal , Animais , Corte , Masculino , Psychodidae/classificação , Especificidade da EspécieRESUMO
A number of insects produce acoustic signals during courtship. Genes involved in the control of the courtship song are particularly interesting from an evolutionary viewpoint because interspecific variation in this signal is potentially important as a reproductive isolation mechanism and, as a consequence, in the speciation process. The cacophony gene was identified by a mutation affecting the "lovesong" in Drosophila melanogaster. Phlebotomine sandflies (Diptera: Psychodidae) also produce acoustic stimuli during courtship and therefore cacophony can be used as an interesting molecular marker in evolutionary studies in these important disease vectors. In this paper we have studied the molecular evolution of the IVS6 region of cacophony in sandflies. We compared the level of divergence in the exon sequences encoding this conserved domain in Drosophila and Phlebotomines. We also analysed the high level of variation in an intron that is present in sandflies but that was lost in Drosophila during evolution. The available cacophony sequences were also used for a phylogenetic analysis of some species of the Neotropical genus Lutzomyia.
Assuntos
Proteínas de Drosophila/genética , Evolução Molecular , Proteínas de Insetos/genética , Psychodidae/genética , Sequência de Aminoácidos , Animais , Sequência de Bases , DNA Complementar , Proteínas de Drosophila/classificação , Éxons , Proteínas de Insetos/classificação , Íntrons , Dados de Sequência Molecular , Filogenia , Psychodidae/classificação , Homologia de Sequência de Aminoácidos , Homologia de Sequência do Ácido NucleicoRESUMO
Using degenerate-primers PCR we isolated and sequenced fragments from the sand fly Lutzomyia longipalpis homologous to two behavioural genes in Drosophila, cacophony and period. In addition we identified a number of other gene fragments that show homology to genes previously cloned in Drosophila. A codon usage table for L. longipalpis based on these and other genes was calculated. These new molecular markers will be useful in population genetics and evolutionary studies in phlebotomine sand flies and in establishing a preliminary genetic map in these important leishmaniasis vectors.
Assuntos
Psychodidae/genética , Sequência de Aminoácidos , Animais , Códon/química , DNA/genética , DNA/isolamento & purificação , Drosophila/genética , Marcadores Genéticos/genética , Dados de Sequência Molecular , Filogenia , Reação em Cadeia da Polimerase , Psychodidae/química , Psychodidae/classificação , Alinhamento de Sequência , Análise de Sequência de DNA , Homologia de Sequência de Aminoácidos , Comportamento Sexual Animal/fisiologiaRESUMO
Lutzomyia longipalpis (Lutz & Neiva, 1912) (Diptera: Psychodidae: Phlebotominae) is a vector of visceral leishmaniasis in the Americas and it might represent a complex of sibling species. Reproductive isolation between closely related species often involves differences in courtship behaviour. cacophony (cac) and period (per) are two Drosophila genes that control features of the "lovesong" males produce during courtship that has been implicated in the sexual isolation between closely related species. We are using gene fragments from L. longipalpis' homologues of these two genes to study the speciation process in this putative species complex.
Assuntos
Corte , Genes de Insetos , Psychodidae/genética , Atrativos Sexuais/genética , Vocalização Animal , Animais , Feminino , Genes de Insetos/genética , Masculino , Polimorfismo Genético , Psychodidae/fisiologia , Comportamento Sexual AnimalRESUMO
Lutzomyia longipalpis (Lutz & Neiva, 1912) (Diptera: Psychodidae: Phlebotominae) is a vector of visceral leishmaniasis in the Americas and it might represent a complex of sibling species. Reproductive isolation between closely related species often involves differences in courtship behaviour. cacophony (cac) and period (per) are two Drosophila genes that control features of the "lovesong" males produce during courtship that has been implicated in the sexual isolation between closely related species. We are using gene fragments from L. longipalpis' homologues of these two genes to study the speciation process in this putative species complex