Meeting Abstract

37.5  Wednesday, Jan. 5  Adaptive sex-ratio bias and the resolution of intralocus sexual conflict COX, R.M.*; DURYEA, M.C.; CALSBEEK, R.; Dartmouth College; Dartmouth College; Dartmouth College robert.m.cox@dartmouth.edu

When selection favors alternative genotypes in each sex, high-fitness parents often produce low-fitness progeny of the opposite sex. Recent studies suggest that this sexual conflict can overwhelm the benefits of mate choice for “good genes” because preferred males incur a net fitness cost through the production of low-quality daughters. Here, we present a counterpoint in a lizard that exhibits strong intralocus sexual conflict over body size. We show that female brown anoles (Anolis sagrei) produce more sons with sperm from high-quality sires of large size and good condition, but more daughters with sperm from low-quality sires of small size and poor condition. By measuring natural selection on progeny in the wild, we show that maximal fitness payoffs are achieved by shifting offspring production from daughters to sons as sire size increases. This occurs because the viability of male progeny increases dramatically with sire size, whereas the viability of female progeny is independent of sire size. Our results suggest that observed patterns of sex-ratio bias with respect to paternal phenotypes allow females to obtain genetic benefits by preferentially producing high-fitness sons via large sires.