Dynamics of biparental care in a burying beetle: experimental handicapping results in partner compensation

Parental care is thought to be costly, as it consumes time and energy. Such costs might be reduced in animal parents that raise their young on valuable food sources such as dung or carcasses, as parents are able to invest in self-maintenance by feeding from the same resource. However, this might lower the nutritional value for other family members and, as a consequence, food competition might arise. To promote our understanding of the outcome of such competition, we manipulated the necessity of parents to feed from the resource. Using a full factorial design, we paired food-deprived or well-fed males with food-deprived or well-fed females of burying beetles, which are known to raise their young on vertebrate cadavers. We found that food-deprived parents consumed more of the carrion than those that were well-fed and this had a negative impact on other family members. However, the outcome of the competition depended on the sex of the parents, with females suffering when males fed more and offspring suffering when females fed more. Thus, family life involves selfish elements, as both parents remove resources for the purpose of self-maintenance. However, females show altruistic aspects, as they appear to restrict their food consumption for the benefit of their offspring when paired with a food-deprived male. Interestingly, males extend their stay with the brood when having faced food scarcity prior to reproduction, presumably to replenish their energy reserves. Our study therefore reveals that breeding on shared resources can promote family living, but also results in competition.

Section: Discussionmentioning

confidence: 98%

Manipulation of parental nutritional condition reveals competition among family members

Keppner

Ayasse

Steiger

2018

“…handicapped) parents reduce their amount of parental care in the closely related N . quadripunctatus (Suzuki & Nagano, ) and N. orbicollis (Creighton et al ., ). Meanwhile, brood size manipulations on N. vespilloides and N. orbicollis show that parents provide more care towards larger broods (Rauter & Moore, ; Smiseth et al ., ).…”

Section: Methodsmentioning

confidence: 97%

“…Burying beetles of the genus Nicrophorus are ideal for studying the joint effects of handicapping and brood size as prior studies show that parents respond to both treatments (handicapping: Suzuki & Nagano, 2009;Creighton et al, 2015;Suzuki, 2016; brood size manipulations: Rauter & Moore, 2004;Smiseth et al, 2007). These beetles breed on carcasses of small vertebrates that serve as the sole food source for the brood during larval development (Eggert et al, 1998;Scott, 1998).…”

Section: Introductionmentioning

confidence: 99%

Flexible parents: joint effects of handicapping and brood size manipulation on female parental care inNicrophorus vespilloides

Ratz

Smiseth

2018

Parental care is highly variable, reflecting that parents make flexible decisions in response to variation in the cost of care to themselves and the benefit to their offspring. Much of the evidence that parents respond to such variation derives from handicapping and brood size manipulations, the separate effects of which are well understood. However, little is known about their joint effects. Here, we fill this gap by conducting a joint handicapping and brood size manipulation in the burying beetle Nicrophorus vespilloides. We handicapped half of the females by attaching a lead weight to their pronotum, leaving the remaining females as controls. We also manipulated brood size by providing each female with 5, 20 or 40 larvae. In contrast to what we predicted, handicapped females spent more time provisioning food than controls. We also found that handicapped females spent more time consuming carrion. Furthermore, handicapped females spent a similar amount of time consuming carrion regardless of brood size, whereas controls spent more time consuming carrion as brood increased. Females spent more time provisioning food towards larger broods, and females were more likely to engage in carrion consumption when caring for larger broods. We conclude that females respond to both handicapping and brood size manipulations, but these responses are largely independent of each other. Overall, our results suggest that handicapping might lead to a higher investment into current reproduction and that it might be associated with compensatory responses that negate the detrimental impact of higher cost of care in handicapped parents.

“…Females often spend more time provisioning food for the larvae and stay on the carcass for longer than males, whereas males spend more time maintaining the carcass (Fetherston et al ., ; Eggert et al ., ; Smiseth & Moore, ; Rauter & Moore, ; Smiseth et al ., ; Walling et al ., ). Previous studies based on mate removal, handicapping, or random‐pairing designs provide mixed evidence with some support for both negotiation (Fetherston et al ., ; Rauter & Moore, ; Smiseth & Moore, ; Smiseth et al ., ; Suzuki & Nagano, ; Creighton et al ., ) and sealed‐bid models (Jenkins et al ., ; Rauter & Moore, ; Smiseth et al ., ; Suzuki & Nagano, ). A recent study on the effects of inbreeding on biparental care found evidence for both negotiation and sealed‐bid models, suggesting that these two mechanisms are not mutually exclusive (Mattey & Smiseth, ).…”

Section: Introductionmentioning

confidence: 99%

State‐dependent cooperation in burying beetles: parents adjust their contribution towards care based on both their own and their partner's size

Pilakouta

Richardson

Smiseth

2015

Handicapping experiments on species with biparental care show that a focal parent increases its contribution when its partner is handicapped. Such results are interpreted as evidence for negotiation, whereby each parent adjusts its amount of care to that of its partner. However, it is currently unclear whether the focal parent responds to a change in its handicapped partner's behaviour or state. To address this gap, we conducted an experiment on the burying beetle Nicrophorus vespilloides where we first generated different-sized males and females by varying the duration of larval development. We then used a 2 9 2 factorial design in which a small or large male was paired with a small or large female. Small females provided less direct care (food provisioning and interactions with larvae) than large females, and both males and females provided less direct care when paired with a small partner. Thus, the focal parent adjusted its contribution towards care based on both its own state and that of its partner. There was also evidence for negotiation between the two parents as the focal parent adjusted its contribution based on the amount of care by its partner. However, there was no evidence that negotiation accounted for how the focal parent responded to its partner's size. Our results have important implications for our understanding of biparental cooperation as they show that each parent adjusts its contribution not only based on the amount of care provided by its partner but also based on its own state and its partner's state.