A latitudinal cline in P-M gonadal dysgenesis potential in Australian Drosophila melanogaster populations.

Abstract

SummaryIsofemale lines ofDrosophila melanogasterfrom six localities along the east coast of Australia, spanning 2900 km and 26 degrees of latitude, were assayed for their gonadal dysgenesis characteristics in theP–Msystem of hybrid dysgenesis. A strong clinal pattern with latitude was discovered. From north to south, the first two populations were typical strongPpopulations, and the next population was moderateP. The next population to the south was neutral (Q), with some weakPand weakMcharacteristics. The two southernmost populations were typicalMpopulations. Much variance inPactivity inPpopulations and in susceptibility toPactivity inMpopulations was detected among isofemale lines. This clinal pattern with latitude of theP–Msystem is paralleled by similar clinal patterns for frequencies of common cosmopolitan inversions and of certain allozymes in Australia. A model of introductions of flies with different characteristics in the north and south could account for theP–Mclinal pattern, but cannot account for an intermediateQpopulation, nor establish the inversion and isoenzyme dines at the same time. Current models of transposable element population dynamics are limited to single population dynamics, and are therefore inadequate for these clinal data.