WITHIN-GENERATION AND BETWEEN-GENERATION EFFECTS OF TEMPERATURE ON EARLY FECUNDITY OF DROSOPHILA-MELANOGASTER

We used a repeated-measures, four-factor experimental design to determ ine how the fecundity of Drosophila melanogaster during the first 5 da ys of adult life was influenced by paternal, maternal, developmental a nd laying temperature, with two different temperature levels (18 degre es C vs. 25 degrees C) per factor. Laying temperature had by far the l argest effect on fecundity and accounted for 79 per cent of the varian ce in overall fecundity: flies laying at 25 degrees C began laying egg s about a day earlier and had much higher daily fecundities than did t hose laying at 18 degrees C. Developmental temperature had no signific ant effect either on overall fecundity or on the pattern of daily egg production. Dam temperature had a slight effect on the pattern of dail y egg production, but not on overall fecundity. In contrast, sire temp erature slightly influenced both overall fecundity and the pattern of daily egg production. Our results demonstrate that early fecundity is extraordinarily sensitive to laying temperature (360 per cent increase if laying at 25 degrees C vs. at 18 degrees C), but is relatively wel l buffered against developmental and cross-generational effects (maxim um effect only 7 per cent, for sire temperature).