Female choice for optimal combinations of multiple male display traits increases offspring survival

Females commonly incorporate information from more than 1 male trait when making mating decisions, which may increase their ability to choose high-quality males. Assessment of multiple male traits may also incur increasing costs of time and/or energy and should therefore provide an adaptive advantage over females that do not exhibit such complex mating decisions. Although this benefit has been assumed/concluded in previous mate choice studies, it has rarely been empirically verified with female fitness data. Here we show that female side-blotched lizards (Uta stansburiana) that assess males for optimal trait combinations of throat color (a polymorphic social signal) and dorsal patterning (a polymorphic antipredator trait) recruit more offspring to the next adult generation. Specifically, females preferred males with a barred dorsal pattern, but only when males were yellow throated (signaling a sneaker strategy in males). Females mated to sires with both these traits experienced high rates of progeny survival to adulthood, via inheritance of favorable genetic combinations from sires (indirect benefits). Previous results suggest that this is because barredness confers crypsis primarily in yellow-throated lizards and not in lizards with alternative throat colors. Together, these results support the hypothesis that female preference for multiple, interacting male traits is an adaptive response to complex patterns of natural selection on offspring, such as correlational selection on unlinked traits. Our results provide new evidence for an adaptive advantage to females that exhibit complex mating-decision rules and suggest that one advantage lies in reducing deleterious recombination of genes for traits that, only in specific combinations, enhance fitness.