93 research outputs found
Phenetic distances in the Drosophila melanogaster-subgroup species and oviposition-site preference for food components
Oviposition-site preferences (O.S.P.) have been investigated in females of six sibling species of the Drosophila melanogaster subgroup. O.S.P. were determined for standard food components and yeast genotypes. Females of all species showed a strong preference for complete medium and avoidance of pure agar as an egg-deposition site.\ud
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Ecological trees of the species on the basis of rank correlations were constructed. In ‘no-choice’ situations they agree with phylogenetic trees obtained by different means but in ‘choice’ situations they do not agree too well.\ud
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All species showed a high egg production on live yeast compared with standard medium (with killed yeast) and D. erecta females demonstrated discrimination between yeast genotypes. Niche breadth calculated from survival on the sterol mutant yeasts correlated fairly well with phylogenetic trees
Evolutionary Genomics of Genes Involved in Olfactory Behavior in the Drosophila melanogaster Species Group
Previous comparative genomic studies of genes involved in olfactory behavior in Drosophila focused only on particular gene families such as odorant receptor and/or odorant binding proteins. However, olfactory behavior has a complex genetic architecture that is orchestrated by many interacting genes. In this paper, we present a comparative genomic study of olfactory behavior in Drosophila including an extended set of genes known to affect olfactory behavior. We took advantage of the recent burst of whole genome sequences and the development of powerful statistical tools to analyze genomic data and test evolutionary and functional hypotheses of olfactory genes in the six species of the Drosophila melanogaster species group for which whole genome sequences are available. Our study reveals widespread purifying selection and limited incidence of positive selection on olfactory genes. We show that the pace of evolution of olfactory genes is mostly independent of the life cycle stage, and of the number of life cycle stages, in which they participate in olfaction. However, we detected a relationship between evolutionary rates and the position that the gene products occupy in the olfactory system, genes occupying central positions tend to be more constrained than peripheral genes. Finally, we demonstrate that specialization to one host does not seem to be associated with bursts of adaptive evolution in olfactory genes in D. sechellia and D. erecta, the two specialists species analyzed, but rather different lineages have idiosyncratic evolutionary histories in which both historical and ecological factors have been involved
Sur quelques Diptères de l'Ile Majorque
En septembre 1958, j'ai en l'occasion d'effectuer une récolte de
Diptères aux environs du village Valldemosa de l'Ile de Majorque
(Baleares). Le résultat de cette récolte est assez maigre en ce qui concerne
le nombre d'espèces récoltées. Cela n'est pas étonnant si l'on
considère la saison tardive et la longue période de sécheresse, quatre
mois de suite sans la moindre pluie. La végétation armuelle était absolument
sèche, voire bralée. Elle ne persistait que près de deux petites
sources et d'un petit réservoir d'eau et c'est lä précisément que j'ai pu
récolter quelques Diptères. Dans les oliveraies environnant le village je
n'ai pas pu trouver méme le Da cus oleae malgré que sur quelques olives
on voyait des piqüres d'ovoposition.Peer reviewe
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