Does Body Size Influence Male Care? Investigating an Alternative Reproductive Tactic in Manogea porracea (Araneae: Araneidae), a Spider with Amphisexual Care

Abstract

The balance between the investment of time and energy by males in searching for new partners and in protecting and/or feeding offspring can influence reproductive strategies. Strong competitors may enhance their mating effort, while weak competitors may compensate their disadvantage in intrasexual competition by investing in the increase of offspring survival. This balance and its implications to male reproductive strategies have been extensively investigated in vertebrate species but remain poorly understood in invertebrates, because paternal care is rare. Manogea porracea is the only described solitary spider in which extended male care occurs in the absence of females (i.e. amphisexual care). Large males usually win disputes and prefer large, more fecund females. Therefore, they may increase their reproductive success by prioritizing the investment in the search for additional partners, while small males may compensate their competitive disadvantage by increasing their own parental efforts. We tested the prediction that lighter males will invest in the care of the offspring more often than heavier ones. However, our results indicate that males care for offspring regardless of their size. We discuss how the benefits of parental care may override the costs of reducing the number of potential mates for M. porracea males and suggest new directions for further studies.