Sex-specific life history dynamics in response to selection for faster development and increased longevity

Trade-offs in resource investment between growth, reproduction and somatic maintenance are key drivers of life history evolution. Although extensively studied using single trait selection in Drosophila melanogaster, the evolutionary responses of simultaneous selection on multiple life history traits are largely unexplored. We investigated sex-specific life history traits evolution in Drosophila melanogaster populations simultaneously selected for faster pre-adult development and increased adult longevity (FLJs) as compared to their ancestral controls (JBs). Both FLJ males and FLJ females emerged with reduced resources, yet their evolutionary responses diverged. FLJ males had comparable pre-copulatory traits and reproductive effectiveness, while achieving higher longevity than JB males. In contrast, FLJ females exhibited significantly reduced lifetime fecundity and fewer ovariole numbers with longevity similar to JB females. These findings indicate a clear sex-specific divergence in resource allocation strategies under identical selection pressures.