Indirect fitness benefits can reinforce the direct fitness benefits of male mate choice.

Mating preferences frequently evolve because they confer fitness benefits to the chooser. While there is strong evidence for both direct and indirect fitness benefits in the context of female mate choice, the potential for males to receive indirect benefits from mate choice remains understudied. Male mate choice for larger female body size is widespread among ectotherms and is generally attributed to the direct fitness benefits larger females provide due to their higher fecundity. However, when female size is heritable or condition-dependent, males could also receive indirect benefits from mating with larger females in the form of increased offspring fitness. We tested this possibility in Drosophila melanogaster by first confirming the direct fitness benefits associated with large females and then comparing the fitness of offspring produced by large versus small females. Although female body size did not influence offspring juvenile viability, large females produced daughters with higher reproductive success than the daughters of small females. Males only received these indirect benefits through their daughters, however, as reproductive success did not differ significantly between the sons of large and small females. Our findings demonstrate that indirect fitness benefits can serve to reinforce the direct benefits of male mate choice, suggesting that indirect effects may play an underappreciated role in the evolution of male preferences.