Contribution of X chromosomal and autosomal genes to species differences in male courtship songs of the <em>Drosophila virilis</em> group species

Abstract In sympatric Drosophila species, songs produced by male wing vibration during courtship are an effective mechanism preventing interspecific matings and maintaining sexual isolation between different species. These songs can vary greatly even between closely related species. The aim of this study was to localise X chromosomal and autosomal genes affecting species differences in male courtship song and to study their interaction in the D. virilis group species. Various genes were probed by in situ hybridisation on the X chromosomes of six species of the group, which enabled us to use localised RFLP markers in QTL studies, as well as to compare gene arrangements of different species. Genetic analyses of differences between the songs of D. virilis and D. littoralis showed that species-specific song traits are affected both by X chromosomal and autosomal genes. The X chromosomal gene(s) having a major impact on pause and pulse length in male song were found to be located at the proximal region of the chromosome. Precise localisation of the song genes was, however, not possible due to multiple chromosome rearrangements restricting recombination between RFLP markers located on this area. The same problem was faced when studying hybrids between D. flavomontana and D. montana with less diverged X chromosomal gene arrangements. Interaction between the X chromosomal and autosomal song genes in determining male song traits was studied in four species belonging to the virilis and montana phylads of D. virilis group. The long pauses in courtship song were found to be mainly caused by X chromosomal song genes (or maternal / cytological factors), while pulse length was determined by X chromosomal genes interacting with autosomal genes. This confirms the important role of X chromosomal gene(s) in song evolution in the montana phylad species. The direction of dominance in hybrid songs suggests that the songs of the montana phylad species have been affected by directional selection favouring shorter pulses and longer pauses between sound pulses during their evolution. The levels and patterns of DNA polymorphism in an X-linked fused (fu) gene was studied in different D. montana populations. These studies revealed that D. montana populations are significantly but not completely isolated, and that a selective sweep at fu (or at a gene linked to fu) may be the reason for the reduced levels and patterns of variability of this gene in Finnish D. montana populations. The methods used in this study will be utilized to study variation in 'song genes' in the future

The genetic architecture of sexually selected traits in two natural populations of Drosophila montana

The work was supported by the National Environment Research Council (grant NE/E015255/1 to MGR and RKB) and the Academy of Finland (project 132619 to AH).We investigated the genetic architecture of courtship song and cuticular hydrocarbon traits in two phygenetically distinct populations of Drosophila montana. To study natural variation in these two important traits, we analysed within-population crosses among individuals sampled from the wild. Hence, the genetic variation analysed should represent that available for natural and sexual selection to act upon. In contrast to previous between-population crosses in this species, no major quantitative trait loci (QTLs) were detected, perhaps because the between-population QTLs were due to fixed differences between the populations. Partitioning the trait variation to chromosomes suggested a broadly polygenic genetic architecture of within-population variation, although some chromosomes explained more variation in one population compared with the other. Studies of natural variation provide an important contrast to crosses between species or divergent lines, but our analysis highlights recent concerns that segregating variation within populations for important quantitative ecological traits may largely consist of small effect alleles, difficult to detect with studies of moderate power.PostprintPeer reviewe

Evaluación visual mediante métodos psicofísicos de las personas sometidas a exposición laboral a solventes orgánicos

Os solventes orgânicos são substâncias neurotóxicas que podem causar efeitos danosos sobre as funções visuais. É comum a exposição ocupacional a esses tipos de substâncias, pois elas apresentam grande aplicabilidade em inúmeras atividades. Os efeitos podem ser quantificados por testes psicofísicos. Os testes mais usados nesse tipo de avaliação são de ordenamento de matizes, como o Teste D15 Dessaturado de Lanthony e o Teste dos 100 Matizes de Farnsworth-Munsell, e avaliação de sensibilidade ao contraste espacial de luminância, como MCT 8000 Vistech, VCTS 6500 Vistech e FACT 101. Em geral esses testes descrevem perda de discriminação de cores, afetando tanto o eixo azul-amarelo quanto o eixo verde-vermelho, e diminuição da sensibilidade ao contraste de luminância principalmente para as frequências espaciais mais baixas. Existe correlação positiva entre os resultados da avaliação psicofísica e vários marcadores biológicos e ambientais, mas essa correlação depende do marcador e do tipo de solvente ao qual os indivíduos são expostos. Fatores como alcoolismo crônico e tabagismo inveterado podem interferir no processo de correlacionar esses resultados.ABSTRACT: Organic solvents are neurotoxic substances that can cause damaging effects in the visual system. Occupational exposure to these substances is common because they are used in a wide variety of activities. These effects can be quantified by specific psychophysical tests. The most commonly used tests for color vision assessment are arrangement tests, such as the Lanthony Panel D-15 desaturated test and the Farnsworth-Munsell 100-hue test, and for contrast sensitivity assessment, printed panel tests such as the MCT 8000 VISTECH, VCTS 6500VISTECH, and FACT 101 tests. Generally, these tests show color discrimination losses in the blue-yellow and red-green axis, and a decrease in contrast sensitivity, mainly at low spatial frequencies. There is a positive correlation between psychophysical results and biological environmental markers, but this correlation depends on the marker and on the kind of solvent to which the individuals are exposed. Factors such as alcohol and tobacco can interfere with the correlation of the results.RÉSUMÉ: Les solvants organiques sont des substances neurotoxiques que peuvent causer des effets préjudiciables dans le système visuel. L exposition professionnelle de ces types de substances est commune parce qu ils sont utilisés dans une grande variété d activités. Ces effets peuvent être quantifiés par des tests spécifiques de psychophysique. Les tests les plus utilisés dans cette évaluation sont, pour la vision des couleurs, le Lanthony Panel D-15 désaturé et le test Farnsworth-Munsell 100-Hue, et pour l évaluation de la sensibilité au contraste, le MCT 8000 Vistech, le VCTS 6500 Vistech et le FACT 101. Généralement, ces tests révèlent une réduction de discrimination des couleurs, des effets dans les axes bleu-jaune et rouge-vert, et une diminution de sensibilité au contraste, spécialement dans les basses fréquences spatiales. Il y a une corrélation positive entre les résultats psychophysiques et les marqueurs biologiques environnementaux, mais cette corrélation dépend du marqueur et du type de solvant auquel le sujet a été exposé. Des facteurs tels que l alcool et le tabac peut nuire à la corrélation des résultats.RESUMEN: Los solventes orgánicos son sustancias neurotóxicas que pueden causar efectos dañinos en el sistema visual. La exposición ocupacional a estas sustancias es común, ya que se utilizan en una amplia variedad de actividades. Estos efectos pueden ser cuantificados por las pruebas psicofísicas específicas. Las pruebas más utilizadas para la evaluación de la visión del color son las pruebas de acuerdo, tales como el Panel de Lanthony D-15 desaturado de prueba y la prueba de Farnsworth-Munsell 100-hue, y para evaluar la sensibilidad al contraste, pruebas impresas panel como el MCT 8000 VISTECH, VCTS 6500VISTECH, y el hecho 101 pruebas. En general, estas pruebas demuestran que las pérdidas de color la discriminación en el eje azul-amarillo y rojo-verde, y una disminución de la sensibilidad al contraste, sobre todo a bajas frecuencias espaciales. Hay una correlación positiva entre los resultados de estudios biológicos y psicofísicos marcadores del medio ambiente, pero esta relación depende de la marca y del tipo de disolvente para que los individuos estén expuestos. Factores tales como el alcohol y el tabaco pueden interferir con la correlación de los resultados