Female spadefoot toads compromise on mate quality to ensure conspecific matings

When high-quality conspecifics resemble heterospecifics, females may be unable to engage effectively in both species recognition and mate-quality recognition. Consequently, females engaging primarily in mate-quality recognition risk heterospecific matings and females engaging primarily in species recognition risk matings with low quality mates. I examined the evolutionary consequences of this conflict between species and mate-quality recognition in spadefoot toads. I compared mate preferences and the fitness consequences of these preferences in spadefoot toad populations that did and did not overlap with congeners. In non-overlapping populations, females preferred an extreme call character resembling that possessed by heterospecifics, and they had more eggs fertilized. In overlapping populations, females preferred those call characteristics that were closest to the norm for their population, and they did not benefit from mate choice. Thus, female spadefoots appear to trade-off species and mate-quality recognition, such that those co-occurring with heterospecifics forego benefits of high-quality matings to ensure conspecific matings.