Reconsidering sex differences during place learning in túngara frogs.

Abstract

In túngara frogs, female mate choice requires remembering the location and/or calls of preferred males who advertise from fixed positions within a breeding pond. A previous study found that, when solving a place discrimination task in the laboratory, female túngara frogs were able to learn a visual cue to solve the task, whereas males were not. In that task, male performance appeared to be inhibited, in part, by their attempt to use egocentric cues. We tested whether the sex difference in place learning previously reported would generalize to other training parameters with different cues available by eliminating the potential to use egocentric cues and increasing the number of trials per day. As before, frogs were given a choice between a red or yellow door, one of which led to shelters and return to their home cage. In the current testing conditions, we detected a preference for the red door; thus, we only considered frogs rewarded to the yellow door. Training was associated with an increase in correct choices and an increased preference for the yellow door. However, there was no evidence for a sex difference in learning. In summary, under the current training conditions, we found that the apparent female advantage in place learning was no longer evident. Future studies that investigate sex differences in cue preference and/or ability to switch among cues will further illuminate the conditions under which sex differences in learning are manifest in túngara frogs.