Adaptive Plasticity in Female Mate Choice Dampens Sexual Selection on Male Ornaments in the

Theory on the evolution of ornamental male traits by sexual selection assumes consistency in selection over time. Temporal variation in female choice could dampen sexual selection, but scant information exists on the degree to which individual female preferences are flexible. Here we show that in lark buntings sexual selection on male traits varied dramatically across years and, in some cases, exhibited reversals in the direction of selection for a single trait. We show that these shifts are probably because of flexibility in mate choice by individual females and that they parallel shifts in the male traits that predict female reproductive success in a given year. Plasticity in choice and concomitant reversals in mating patterns across time may weaken the strength of sexual selection and could maintain genetic variation underlying multiple sexual ornaments. Sexual selection for exaggerated secondarysexual traits arises from two different mech-anisms that result in correlations between male traits and mating success—male-male com-petition for access to females and female mate choice (1, 2). These mechanisms can be difficult to disentangle (3), but direct female choice for extravagant male traits has been shown in man