Social preferences in spadefoot toads
To test our hypothesis that the preoptic area mediates social preferences, and is central to their evolution, we turned to the Plains spadefoot toad. Female Plains spadefoot toads modify their mate choice according to their body condition.
We found that dopamine and norepinephrine in the preoptic area were sensitive to body condition and were higher in response to the preferred mating call, even when the preferred call differed according to body condition. When we compare to a close relative without condition-dependent mate choice, we found that only in the Plains spadefoot does body condition change how the preoptic area responds to social signals.
These results suggest that norepinephrine and/or dopamine signaling in the preoptic area could have been a target of selection in the evolution of condition-dependent preferences in Plains spadefoot toads.