Trade-off of ovarian lipids and total body lipids for fecundity and starvation resistance in tropical populations of Drosophila melanogaster.

Abstract

In Drosophila melanogaster, clines of starvation resistance along a latitudinal gradient (south to north) have been reported in India, which matched with their cline for total body lipids (TL ). Nevertheless, producing too many reserves is likely to be costly and a trade-off might exist with life-history traits. Previous studies on starvation resistance and life-history traits of D.melanogaster have mainly focused on quantification of total body lipids, instead of separating ovarian lipids from total body lipids. In the present study, we have quantified absolute ovarian lipids (OL ) versus absolute body lipids excluding ovarian lipids (BL ) and examined associations with fecundity as well as starvation resistance in two latitudinal populations (8.34 vs. 32.43°N) of D.melanogaster. Firstly, we observed a trade-off between BL and OL that matched the trade-off of starvation resistance, longevity versus fecundity and development time in latitudinal populations of D.melanogaster. Southern populations had higher starvation resistance, more BL and lesser OL, whereas northern populations had enhanced fecundity, OL and lesser BL . Secondly, within population, starvation resistance also correlated with BL , and fecundity with OL . However, there was no correlation between starvation resistance and OL . Moreover, there was utilization of BL and nonutilization of OL under starvation stress. Therefore, resources invested for fecundity in the form of OL were independent of evolved starvation resistance in D.melanogaster. Our results suggest that a common pool of energy storage compounds (lipids) are allocated differentially between fecundity and starvation resistance and are consistent with Y-model of resource allocation.