Environmental constraints on size-dependent signaling affects mating and rival interactions

Advertisement signals can convey information about a sender’s characteristics, such as body size. The reliability of signals, however, can be reduced when signal production is partially dependent on the environment. Here we show that display site properties can affect signal production and consequently signal attractiveness in a size-dependent manner. We recorded male túngara frogs (Physalaemus pustulosus) while manipulating water levels in order to constrain calling. We found that water level affected male call properties in a size-dependent manner, with call amplitude being less affected in smaller males when forced to call in shallow water. Next, we tested how size-dependent and display site-dependent signaling affected female choice and rival competition. Both males and females showed the strongest response to the call of a large male when he was calling at the deepest water levels. However, females showed no preference for large over small males when both were recorded in shallow w...