Genomic P elements and P-M characteristics of eastern Australian populations of Drosophila melanogaster

As part of our effort to monitor changes in the clinal pattern of P element -associated traits in eastern Australian Drosophilamelanogaster, we investi gated the genomic P elements of 293 isofemale lines collected in the period 1991-1994 from 45 localities. P elements were present in many copies in al l genomes examined, with full-size P and KP element size classes accounting for the large majority. SR elements were not present in at least 92% of th e lines tested. South of about 26 degrees south Latitude (degrees SLat), th e ratio of KP to full-size P elements (KP/P ratio) increased, correlating w eakly with the P-M phenotypes of the populations, from moderately P populat ions (26-29 degrees SLat) to M populations (37-38 degrees SLat) North of 26 degrees SLat, in weak P populations, the KP/P ratio was higher than betwee n 26 and 29 degrees Slat. The KP/P ratio appears to be higher in the northe rn populations than it was when previous studies were done. Overall, a high KP/P ratio among lines correlated roughly with a lack of P activity, but i t also correlated with reduced repressor function. In a sample of 30 lines, a maternal effect of repressor function did not show a pattern with latitu de, nor with KP/P ratio, nor with presence or absence of P activity.