Female mate choice and the potential for ornament evolution in túngara frogs Physalaemus pustulosus

The potential for ornament evolution in response to sexual selection rests on the interaction between the permissivenessor selectivity of female preferences and the constraints on male development of signaling related traits. We investigate theformer by determining how latent female preferences either exaggerate the magnitude of current traits (i.e. elaborations) or favornovel traits (i.e. innovations). In tunngara frogs, females prefer complex mating calls (whine-chucks) to simple calls (whine only).The whine is critical for mate recognition while the chuck further enhances the attractiveness of the call. Here we use a combinationof synthetic and natural stimuli to examine latent female preferences. Our results show that a diversity of stimuli, includingconspecific and heterospecific calls as well as predator-produced and human-made sounds, increase the attractiveness of a callwhen added to a whine. These stimuli do not make simple calls more attractive than a whine-chuck, however. In rare cases wefound stimuli that added to the whine decrease the attractiveness of the call. Overall, females show strong preferences for bothelaborations and innovations of the chuck. We argue that the emancipation of these acoustic adornments from mate recognitionallows such female permissiveness, and that male constraints on signal evolution are probably more important in explaining whymales evolved their specific adornment. Experimentally probing latent female preferences for stimuli out of the species’ range is auseful means to gain insights about the potential of female choice to influence signal evolution and thus the astounding diversityin male sexually-selected traits [Current Zoology 56 (3): 343-357, 2010].