HIGH-RATE OF MOVEMENT OF ONE (MDG3) OUT OF 4 TRANSPOSABLE ELEMENTS INA NATURAL-POPULATION OF DROSOPHILA-MELANOGASTER

We have analysed by in situ hybridization the insertion site polymorph ism of the copia, mdg1, mdg3, and p transposable elements in diploid g enomes of wild males from a natural population of Drosophila melanogas ter. The values of observed average degree of individual heterozygosit y for all elements except mdg3 deviate statistically from the values e xpected by site frequencies, revealing a tendency toward homozygosity as if drift or a structuration in the population was operating. The hi gh degree of heterozygosity for mdg3 which in addition does not deviat e from the expected value, suggests that recent high rate of movements has strongly countered the populational host effect on this element. Hence, heterozygosity for TEs may well reflect the history of the popu lation, and reveals temporary high rate of site movement existing in n atural populations