Tuyển tập báo cáo các nghiên cứu khoa học quốc tế ngành y học dành cho các bạn tham khảo đề tài: Thoracic trident pigmentation in Drosophila melanogaster : Differentiation of geographical populations | Génét. Sél. Evol. 1985 17 2 211-224 Thoracic trident pigmentation in Drosophila melanogaster Differentiation of geographical populations . DAVID p. CAPY Véronique PAYANT and s. TSAKAS . Laboratoire de Biologie et Génétique evolutive F 91190 Gif-sur-Yvette Department of Genetics Agricultural College Athens Greece Summary A phenotypic classification of trident pigmentation allowed the characterization of any natural population by a pigmentation score ranging from 0 to 3. After some training independent observers could produce very similar score values. Growth temperature influences pigmentation intensity and the response curves exhibit a U-shape with a minimum at about 25 C. For the description of natural populations 2 different growth temperatures 17 C and 25 C were chosen. Crosses between a dark French strain and a light Afrotropical strain produced intermediate offspring but a clear maternal effect differentiated the reciprocal Fl s. Numerous populations from various part of the world were investigated and results arranged according to the latitude. For temperate populations collected between 34 and 48 of latitude a steep cline was observed pigmentation being much more darker in high latitude suggesting an adaptive pressure on this phenotype environmental factors which may explain this cline being temperature insolation and desiccation. In tropical populations on the other hand a large variability was observed but without any relation to latitude. Key words Drosophila melanogaster pigmentation temperature response maternal effect latitudinal cline. Résumé La pigmentation thoracique en forme de trident chez Drosophila melanogaster differentiation de populations de diverses origines géographiques Une classification phenotypique de la pigmentation du trident thoracique a permis de caractériser une population natureile par un score de pigmentation variant entre 0 et 3. Après tin certain entramement des observateurs indépendants ont pu obtenir des scores très
