Effects of egg attendance on male mating success in a harvestman with exclusive paternal care

Abstract

The expected quality of paternal behavior can influence female mating decisions and determine male mating success. We evaluated the importance of oviposition site quality, male body size, parental status (presence vs. absence of eggs under males' protection), and time invested in care (less vs. more than 1 month) for male mating success in the harvestman Iporangaia pustulosa. The chances of acquiring a clutch are relatively small for noncaring males but increase nearly 4 times once males start caring for eggs. After 1 month of caring, the chances of acquiring an additional clutch show a marked decline, probably because the cumulative energetic costs imposed by paternal care decreases males' attractiveness or their ability to replenish gametes throughout the caring period. Therefore, male mating success seems to be affected by a combination of presence of eggs and body condition while caring. Because the presence of eggs increases male attractiveness, we also conducted a field experiment removing caring males from their broods and expected that noncaring males would adopt unattended broods as a deceptive strategy to acquire matings. However, noncaring males cannibalized eggs and no brood adoption was recorded. Because well-fed males stay stationary on the vegetation waiting for mating opportunities, unattended broods may have been found more often by vagrant and poorly fed males. We argue that detailed comprehension of the costs and the benefits of paternal activities, as well as the direct benefits of female preference, is fundamental to better understand the interaction between male care and female mate choice.