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ABSTRACT: A latitudinal cline in characteristics associated with the P DNA transposable element is well known in eastern Australian populations of Drosophila melanogaster. In order to survey the long-term patterns of P-M system characteristics and genomic P element content, we established 292 isofemale lines from 54 localities in 1996-1997 and evaluated them for gonadal dysgenesis (GD) sterility and the ratio of KP to full-size P elements (KP/FP ratio). The results were compared to those from collections made in 1983-1986 and 1991-1994. Over 10-14 years, 1) the cross A GD scores of the northern-middle populations declined dramatically; 2) the clinal pattern of the cross A* GD scores did not change; 3) the latitudinal pattern of the KP/FP ratio did not change. The results suggest that only a few P elements determine P-M characteristics and that there has been selection for genomes with fewer active P elements, but not for a great change in proportions of size classes.
Genes & Genetic Systems 01/2008; 82(6):479-87. · 0.95 Impact Factor
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ABSTRACT: As part of our effort to monitor changes in the clinal pattern of P element-associated traits in eastern Australian Drosophila melanogaster, we investigated 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 all 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 the lines tested. South of about 26° south Latitude (°SLat), the ratio of KP to full-size P elements (KP/P ratio) increased, correlating weakly with the P-M phenotypes of the populations, from moderately P populations
(26–29°SLat) to M populations (37–38°SLat) North of 26°SLat, in weak P populations, the KP/P ratio was higher than between
26 and 29°Slat. The KP/P ratio appears to be higher in the northern 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 it also correlated with reduced repressor
function. In a sample of 30 lines, a maternal effect of repressor function did not show a pattern with latitude, nor with
KP/P ratio, nor with presence or absence of P activity.
Genetica 04/1999; 106(3):231-245. · 2.15 Impact Factor
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ABSTRACT: As part of our effort to monitor changes in the clinical pattern of P element-associated traits in eastern Australian Drosophila melanogaster, we investigated 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 all 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 the lines tested. South of about 26 degrees south Latitude (degree SLat), the ratio of KP to full-size P elements (KP/P ratio) increased, correlating weakly with the P-M phenotypes of the populations, from moderately P populations (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 between 26 and 29 degrees Slat. The KP/P ratio appears to be higher in the northern 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 it also correlated with reduced repressor function. In a sample of 30 lines, a maternal effect of repressor function did not show a pattern with latitude, nor with KP/P ratio, nor with presence or absence of P activity.
Genetica 02/1999; 106(3):231-45. · 2.15 Impact Factor
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ABSTRACT: The latitudinal cline in P transposable element-associated characteristics in eastern Australian populations of Drosophila
melanogaster has changed between 1986 and 1991–1994. New collections were made in 1991–1994 from localities along the eastern
coast of Australia. P element-associated properties of 256 isofemale lines from 43 localities were evaluated using gonadal
dysgenesis and/or singed-weak hypermutability assays. The overall results indicate that both P activity and P susceptibility
have declined, with all populations showing a tendency towards a state with little P activity potential but with P repressor
function (neutral or ‘Q’). P repressor function is strong in all populations except some of the most southerly. P activity
potential peaks at about 27° SLat, and drops off to the south (as in 1983–1986 collections) and to the north (in contrast
to 1983–1986 collections); thus the cline is no longer a simple P-to-Q-to-M pattern from north to south, but is now Q-P-Q-M.
A mtDNA RFLP that putatively distinguishes North American and European populations varies in frequency among the populations
but the frequency does not vary clinally with latitude, ruling out massive introductions from North America and Europe as
causing the cline.
Genetica 04/1998; 104(1):45-57. · 2.15 Impact Factor
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ABSTRACT: The latitudinal cline in P transposable element-associated characteristics in eastern Australian populations of Drosophila melanogaster has changed between 1986 and 1991-1994. New collections were made in 1991-1994 from localities along the eastern coast of Australia. P element-associated properties of 256 isofemale lines from 43 localities were evaluated using gonadal dysgenesis and/or singed-weak hypermutability assays. The overall results indicate that both P activity and P susceptibility have declined, with all populations showing a tendency towards a state with little P activity potential but with P repressor function (neutral or 'Q'). P repressor function is strong in all populations except some of the most southernly. P activity potential peaks at about 27 degrees SLat, and drops off to the south (as in 1983-1986 collections) and to the north (in contrast to 1983-1986 collections); thus the cline is no longer a simple P-to-Q-to-M pattern from north to south, but is now Q-P-Q-M. A mtDNA RFLP that putatively distinguishes North American and European populations varies in frequency among the populations but the frequency does not vary clinically with latitude, ruling out massive introductions from North America and Europe as causing the cline.
Genetica 02/1998; 104(1):45-57. · 2.15 Impact Factor
