| comparative evolution of p-m system and infection by the sigma virus in french and spanish populations of drosophila melanogaster. | in 1983, an extensive survey of populations of d. melanogaster was started in a southern french region (languedoc) in two non-mendelian systems: the p-m system of transposable elements and the hereditary rhabdovirus sigma. unexpectedly fast-evolving phenomena were observed and interesting correlations were noted, giving similar geographical pattern to the region in both systems. for these reasons, the analysis was continued and extended towards the north (rhône valley) and the south (spain). in ... | 1992 | 1334901 |