Seasonal variation of sexually dimorphic spatial learning implicates mating system in the intertidal Cocos Frillgoby (Bathygobius cocosensis)

Spatial learning is an important cognitive function found across a multitude of species. Natural selection can enhance specific cognitive abilities depending on species ecology but, under certain conditions, spatial learning is also known to vary between sexes according to reproductive status. Despite abundant studies on spatial learning across animal taxa, those focusing on sexually dimorphic spatial learning have been largely limited to rodents. Here, we found that spatial cognition varies between the sexes in an intertidal goby, and this difference fluctuates across seasons. Males and females demonstrated similar cognitive abilities when solving a simple maze during all seasons except spring, when males were significantly less successful than females. Spring marks the beginning of the breeding season for this species, when females move between nests to choose a suitable mate, while males guard their nest and forego foraging excursions. We suggest that the reduction in male cognitive ability reduces metabolic costs at a time of reduced need. This study presents the first evidence for sexually dimorphic spatial learning in fish driven by differences in reproductive behaviour as dictated by the mating system.