TAILIEUCHUNG - Báo cáo khoa hoc:"Body size reaction norms in Drosophila melanogaster: temporal stability and genetic architecture in a natural population"

Tuyển tập các báo cáo nghiên cứu về sinh học được đăng trên tạp chí sinh học thế giới đề tài: Body size reaction norms in Drosophila melanogaster: temporal stability and genetic architecture in a natural population | Genet. Sei. Evol. 31 1999 491-508 Inra Elsevier Paris 491 Original article Body size reaction norms in Drosophila melanogaster temporal stability and genetic architecture in a natural population Dev Karan Jean-Philippe Morin Emmanuelle Gravot Brigitte Moreteau Jean R. David Laboratoire populations génétique et evolution Centre national de la recherche scientifique 91198 Gif-sur-Yvette cedex France Received 2 March 1999 accepted 16 August 1999 Abstract - A natural population of Drosophila melanogaster was sampled twice over a 5-year interval from the same French locality in the same season. Reaction norms of wing and thorax length and wing thorax ratio according to growth temperature 12-31 C were analysed in ten isofemale lines for each sample. Reaction norms were very similar between years showing not only a remarkable stability of the average size but also of the reactivity to temperature. Wing and thorax length reaction norms were characterized by the co-ordinates of their maxima MV maximum value of character TMV temperature of maximum value . The wing thorax ratio which exhibited a decreasing sigmoid norm was characterized by the co-ordinates of the inflexion point. Again these characteristic values were found to be very similar for samples between years. The results were further analysed by pooling the 20 lines into a single data set. Heritability was significantly variable according to temperature but in a fairly irregular way with lowest values at extreme temperatures. Genetic variance of the three traits exhibited more regular variation with a minimum at intermediate temperatures and maxima at extreme high or low temperatures. Such was also the case of evolvability . the genetic coefficient of variation. Heritability and evolvability were found to be slightly but negatively correlated showing that they provide independent biological information. The temporal stability of a natural population over the years suggests some stabilizing selection for both mean

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