The mate choice mind: studying mate preference, aversion and social cognition in the female poeciliid brain

Male phenotypes vary across mating systems, but what about the female mind? In poeciliid fishes, we observe that female response towards males varies, both at inter- and intraspecific levels. By using the natural variation in poeciliid male reproductive phenotypes, we can probe female responses in different social contexts to isolate the neuromolecular components associated with mate choice. Female Xiphophorus nigrensis exhibit differential nonapeptide (isotocin, vasotocin) gene expression between social contexts that differ by social affiliation; while differential expression of synaptic plasticity genes (neuroserpin, neuroligin-3, NMDAR) is more strongly predictive of social contexts that differ by mate preference discrimination. Gene expression and pharmacological manipulation with X. nigrensis females suggests that the social cognition task of mate choice involves neuromolecular processes linked to learning at the cellular (synaptic plasticity genes) and regional (amygdala and hippocampus) levels. Comparative assays between two poeciliid species with different mating systems provide the first hint of a shared neuromolecular pathway underlying female mate preference response. Yet, it is still unclear how specific components of this neuromolecular pathway (nonapeptides and synaptic plasticity processes) interact to coordinate behavioural tasks associated with mate choice encounters (vigilance, affiliation, evaluation and discrimination). Nevertheless, this collection of studies, coupled with the natural diversity of poeciliid mating systems, pave the way for exciting new insights into the social cognition of mate choice.