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1.
Front Genet ; 9: 359, 2018.
Artigo em Inglês | MEDLINE | ID: mdl-30250479

RESUMO

Introgression should no longer be considered as rare a phenomenon as once thought, since several studies have recently documented gene flow between closely related and radiating species. Here, we investigated evolutionary relationships among three closely related species of fruit flies of the Anastrepha fraterculus group (Anastrepha fraterculus, A. obliqua and A. sororcula). We sequenced a set of 20 genes and implemented a combined populational and phylogenetic inference with a model selection approach by an ABC framework in order to elucidate the demographic history of these species. The phylogenetic histories inferred from most genes showed a great deal of discordance and substantial shared polymorphic variation. The analysis of several population and speciation models reveal that this shared variation is better explained by introgression rather than convergence by parallel mutation or incomplete lineage sorting. Our results consistently showed these species evolving under an isolation with migration model experiencing a continuous and asymmetrical pattern of gene flow involving all species pairs, even though still showed a more closely related relationship between A. fraterculus and A. sororcula when compared with A. obliqua. This suggests that these species have been exchanging genes since they split from their common ancestor ∼2.6 MYA ago. We also found strong evidence for recent population expansion that appears to be consequence of anthropic activities affecting host crops of fruit flies. These findings point that the introgression here found may have been driven by genetic drift and not necessary by selection, which has implications for tracking and managing fruit flies.

2.
Genome Biol Evol ; 10(1): 380-395, 2018 01 01.
Artigo em Inglês | MEDLINE | ID: mdl-29346618

RESUMO

Several studies have demonstrated that genes differentially expressed between sexes (sex-biased genes) tend to evolve faster than unbiased genes, particularly in males. The reason for this accelerated evolution is not clear, but several explanations have involved adaptive and nonadaptive mechanisms. Furthermore, the differences of sex-biased expression patterns of closely related species are also little explored out of Drosophila. To address the evolutionary processes involved with sex-biased expression in species with incipient differentiation, we analyzed male and female transcriptomes of Anastrepha fraterculus and Anastrepha obliqua, a pair of species that have diverged recently, likely in the presence of gene flow. Using these data, we inferred differentiation indexes and evolutionary rates and tested for signals of selection in thousands of genes expressed in head and reproductive transcriptomes from both species. Our results indicate that sex-biased and reproductive-biased genes evolve faster than unbiased genes in both species, which is due to both adaptive pressure and relaxed constraints. Furthermore, among male-biased genes evolving under positive selection, we identified some related to sexual functions such as courtship behavior and fertility. These findings suggest that sex-biased genes may have played important roles in the establishment of reproductive isolation between these species, due to a combination of selection and drift, and unveil a plethora of genetic markers useful for more studies in these species and their differentiation.


Assuntos
Evolução Molecular , Genes de Insetos , Tephritidae/genética , Animais , Feminino , Fluxo Gênico , Masculino , Isolamento Reprodutivo , Seleção Genética , Caracteres Sexuais , Tephritidae/fisiologia , Transcriptoma
3.
Sci Rep ; 6: 17480, 2016 Jan 28.
Artigo em Inglês | MEDLINE | ID: mdl-26818909

RESUMO

The West Indian fruit fly, Anastrepha obliqua, is an important agricultural pest in the New World. The use of pesticide-free methods to control invasive species such as this reinforces the search for genes potentially useful in their genetic control. Therefore, the study of chemosensory proteins involved with a range of responses to the chemical environment will help not only on the understanding of the species biology but may also help the development of environmentally friendly pest control strategies. Here we analyzed the expression patterns of three OBP genes, Obp19d_2, Obp56a and Obp99c, across different phases of A. obliqua development by qPCR. In order to do so, we tested eight and identified three reference genes for data normalization, rpl17, rpl18 and ef1a, which displayed stability for the conditions here tested. All OBPs showed differential expression on adults and some differential expression among adult stages. Obp99c had an almost exclusive expression in males and Obp56a showed high expression in virgin females. Thereby, our results provide relevant data not only for other gene expression studies in this species, as well as for the search of candidate genes that may help in the development of new pest control strategies.


Assuntos
Perfilação da Expressão Gênica , Regulação da Expressão Gênica no Desenvolvimento , Genes de Insetos , Proteínas de Insetos/genética , Receptores Odorantes/genética , Tephritidae/crescimento & desenvolvimento , Tephritidae/genética , Algoritmos , Animais , Feminino , Estudos de Associação Genética , Proteínas de Insetos/metabolismo , Estágios do Ciclo de Vida/genética , Masculino , Receptores Odorantes/metabolismo , Padrões de Referência , Reprodução/genética
4.
PLoS One ; 7(3): e33446, 2012.
Artigo em Inglês | MEDLINE | ID: mdl-22428050

RESUMO

The gene doublesex (dsx) is considered to be under strong selective constraint along its evolutionary history because of its central role in somatic sex differentiation in insects. However, previous studies of dsx used global estimates of evolutionary rates to investigate its molecular evolution, which potentially miss signals of adaptive changes in generally conserved genes. In this work, we investigated the molecular evolution of dsx in the Anastrepha fraterculus species group (Diptera, Tephritidae), and test the hypothesis that this gene evolved solely by purifying selection using divergence-based and population-based methods. In the first approach, we compared sequences from Anastrepha and other Tephritidae with other Muscomorpha species, analyzed variation in nonsynonymous to synonymous rate ratios (dN/dS) in the Tephritidae, and investigated radical and conservative changes in amino acid physicochemical properties. We show a general selective constraint on dsx, but with signs of positive selection mainly in the common region. Such changes were localized in alpha-helices previously reported to be involved in dimer formation in the OD2 domain and near the C-terminal of the OD1 domain. In the population-based approach, we amplified a region of 540 bp that spanned almost all of the region common to both sexes from 32 different sites in Brazil. We investigated patterns of selection using neutrality tests based on the frequency spectrum and locations of synonymous and nonsynonymous mutations in a haplotype network. As in the divergence-based approach, these analyses showed that dsx has evolved under an overall selective constraint, but with some events of positive selection. In contrast to previous studies, our analyses indicate that even though dsx has indeed evolved as a conserved gene, the common region of dsx has also experienced bouts of positive selection, perhaps driven by sexual selection, during its evolution.


Assuntos
Proteínas de Ligação a DNA/genética , Evolução Molecular , Modelos Genéticos , Seleção Genética , Tephritidae/genética , Animais , Sequência de Bases , Brasil , Primers do DNA/genética , Genética Populacional , Haplótipos/genética , Funções Verossimilhança , Dados de Sequência Molecular , Análise de Sequência de DNA , Especificidade da Espécie , Estatísticas não Paramétricas
5.
BMC Evol Biol ; 10: 293, 2010 Sep 24.
Artigo em Inglês | MEDLINE | ID: mdl-20868501

RESUMO

BACKGROUND: Many genes involved in the sex determining cascade have indicated signals of positive selection and rapid evolution across different species. Even though fruitless is an important gene involved mostly in several aspects of male courtship behavior, the few studies so far have explained its high rates of evolution by relaxed selective constraints. This would indicate that a large portion of this gene has evolved neutrally, contrary to what has been observed for other genes in the sex cascade. RESULTS: Here we test whether the fruitless gene has evolved neutrally or under positive selection in species of Anastrepha (Tephritidae: Diptera) using two different approaches, a long-term evolutionary analysis and a populational genetic data analysis. The first analysis was performed by using sequences of three species of Anastrepha and sequences from several species of Drosophila using the ratio of nonsynonymous to synonymous rates of evolution in PAML, which revealed that the fru region here studied has evolved by positive selection. Using Bayes Empirical Bayes we estimated that 16 sites located in the connecting region of the fruitless gene were evolving under positive selection. We also investigated for signs of this positive selection using populational data from 50 specimens from three species of Anastrepha from different localities in Brazil. The use of standard tests of selection and a new test that compares patterns of differential survival between synonymous and nonsynonymous in evolutionary time also provide evidence of positive selection across species and of a selective sweep for one of the species investigated. CONCLUSIONS: Our data indicate that the high diversification of fru connecting region in Anastrepha flies is due at least in part to positive selection, not merely as a consequence of relaxed selective constraint. These conclusions are based not only on the comparison of distantly related taxa that show long-term divergence time, but also on recently diverged lineages and suggest that episodes of adaptive evolution in fru may be related to sexual selection and/or conflict related to its involvement in male courtship behavior.


Assuntos
Proteínas de Insetos/genética , Seleção Genética/genética , Tephritidae/genética , Animais , Proteínas de Drosophila/genética , Haplótipos , Masculino , Proteínas do Tecido Nervoso/genética , Filogenia , Fatores de Transcrição/genética
6.
Biotechnol Lett ; 27(17): 1273-6, 2005 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-16215824

RESUMO

An N-acetylglucosaminidase produced by Streptomyces cerradoensis was partially purified giving, by SDS-PAGE analysis, two main protein bands with Mr of 58.9 and 56.4 kDa. The Km and Vmax values for the enzyme using p-nitrophenyl-beta-N-acetylglucosaminide as substrate were of 0.13 mM: and 1.95 U mg(-1) protein, respectively. The enzyme was optimally activity at pH 5.5 and at 50 degrees C when assayed over 10 min. Enzyme activity was strongly inhibited by Cu2+ and Hg2+ at 10 mM, and was specific to substrates containing acetamide groups such as p-nitrophenyl-beta-N-acetylglucosaminide and p-nitrophenyl-beta-D-N,N'-diacetylchitobiose.


Assuntos
Acetilglucosaminidase/química , Acetilglucosaminidase/isolamento & purificação , Proteínas de Bactérias/química , Proteínas de Bactérias/isolamento & purificação , Streptomyces/enzimologia , Eletroforese em Gel de Poliacrilamida , Temperatura Alta , Concentração de Íons de Hidrogênio , Peso Molecular , Especificidade por Substrato
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