A sustained change in the supply of parental care causes adaptive evolution of offspring morphology

Jarrett, Benjamin J. M.; Evans, Emma; Haynes, Hannah B.; Leaf, Miranda R.; Rebar, Darren; Duarte, Ana; Schrader, Matthew; Kilner, Rebecca M.

doi:10.1038/s41467-018-06513-6

Cited by 34 publications

(71 citation statements)

References 52 publications

(56 reference statements)

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“…; Jarrett et al. ). The facultative nature of posthatching parental care makes this an excellent species in which to examine the effect of parental care on the expression and maintenance of phenotypic variation (Smiseth et al.…”

Section: Methodsmentioning

confidence: 98%

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Parental care and sibling competition independently increase phenotypic variation among burying beetle siblings

2018

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Several recent hypotheses suggest that parental care can influence the extent of phenotypic variation within populations; however, there have been few tests of these ideas. We exploited the facultative nature of posthatching parental care in the burying beetle, Nicrophorus vespilloides, to test whether parental care influences the expression of phenotypic variation in an important fitness trait (body size). We found that parental care and brood size (which influences sibling competition) had positive and independent effects on variation in body size. First, the mean coefficient of variation (CV) of body size was significantly greater in broods that received care than in those that did not. Second, CV body size increased with brood size in both parental care treatments. These results are not consistent with predictions from recent hypotheses that predict parental care will reduce phenotypic variation among siblings. The positive effects of parental care and brood size on phenotypic variation that we observed are likely due to sibling competition for access to provisioning parents and competition for limiting resources contained in the breeding carcass. Our results suggest that future theory linking parental care to the generation and maintenance of phenotypic variation must integrate the nature of interactions among family members.

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Section: Methodsmentioning

confidence: 98%

“…Although parents in this treatment were not forced to provide care to their larvae, previous work has shown that under these conditions the parents care for the brood for at least the first 24 hours after hatching (Jarrett et al. ), which is the time period during which parental care is most beneficial to larvae (Eggert et al. ).…”

Section: Methodsmentioning

confidence: 99%

Parental care and sibling competition independently increase phenotypic variation among burying beetle siblings

2018

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“…This cooperative effort is probably achieved through multiple sets of mandibles working simultaneously on the carcass (Jarrett et al ., in press [31]). Larvae that fail in this task die within 8 h of hatching [24].…”

Section: Discussionmentioning

confidence: 99%

Adaptive evolution of synchronous egg-hatching in compensation for the loss of parental care

et al. 2018

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Interactions among siblings are finely balanced between rivalry and cooperation, but the factors that tip the balance towards cooperation are incompletely understood. Previous observations of insect species suggest that (i) sibling cooperation is more likely when siblings hatch at the same time, and (ii) this is more common when parents provide little to no care. In this paper, we tested these ideas experimentally with the burying beetle, Nicrophorus vespilloides. Burying beetles convert the body of a small dead vertebrate into an edible nest for their larvae, and provision and guard their young after hatching. In our first experiment, we simulated synchronous or asynchronous hatching by adding larvae at different intervals to the carrion-breeding resource. We found that ‘synchronously’ hatched broods survived better than ‘asynchronously’ hatched broods, probably because ‘synchronous hatching’ generated larger teams of larvae, that together worked more effectively to penetrate the carrion nest and feed upon it. In our second experiment, we measured the synchronicity of hatching in experimental populations that had evolved for 22 generations without any post-hatching care, and control populations that had evolved in parallel with post-hatching care. We found that larvae were more likely to hatch earlier, and at the same time as their broodmates, in the experimental populations that evolved without post-hatching care. We suggest that synchronous hatching enables offspring to help each other when parents are not present to provide care. However, we also suggest that greater levels of cooperation among siblings cannot compensate fully for the loss of parental care.

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“…In many altricial systems, offspring evolve reduced size in structures that promote independence (Derrickson, ; Nalepa et al, ; Nice, ; O'Reilly et al, ; Ricklefs, ; Werneburg et al, ). Here, we expected independent larvae that might need to self‐feed to have larger mandibles, as mandible size is correlated to feeding ability is observed in other insects (Bernays, ) and larvae of the facultative species N. vespilloides have evolved larger mandibles during experimental adaptation to the absence of parental care (Jarrett et al, ). However, for the two species examined here, we found no such trend.…”

Section: Discussionmentioning

confidence: 99%

“…We focus our attention on the mandible, which is the primary feeding tool for many insects (Chapman & de Boer, ) and is frequently associated with variations in feeding performance (Bernays, ; Hochuli, ). Furthermore, experimental populations of third instar N. vespilloides larvae were recently found to evolve larger mandibles in the absence of parental care, suggesting a role for mandibles in self‐feeding ability (Jarrett et al, ). Specifically, we predicted that the mandibles of first instars of obligate care species would display markedly different morphology from all other larvae, as their evolution should be unconstrained by the need to self‐feed.…”

Section: Introductionmentioning

confidence: 99%

Variation in mandible development and its relationship to dependence on parents across burying beetles

Benowitz

Sparks

McKinney

et al. 2018

Ecology and Evolution

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BackgroundIn species with parental care, there is striking variation in offspring dependence at birth, ranging from feeding independence to complete dependency on parents for nutrition. Frequently, highly dependent offspring further evolve reductions or alterations of morphological traits that would otherwise promote self‐sufficiency. Here, we examine evidence for morphological evolution associated with dependence in burying beetles (Nicrophorus spp.), in which dependence upon parents appears to have several independent origins. In many species, precocial first instar larvae can survive without parenting, but several altricial species die at this stage on their own. We focused specifically on the mandibles, which are expected to be related to feeding ability and therefore independence from parents.ResultsWe find no evidence that the size of the mandible is related to dependence on parents. However, we do find a developmental and phylogenetic correlation between independence and the presence of serrations on the inner edge of the mandible. Mandibles of independent species bear serrations at hatching, whereas dependent species hatch with smooth mandibles, only developing serrations in the second instar when these larvae gain the ability to survive on their own. Phylogenetic evidence suggests that serrations coincide with independence repeatedly. We note a single exception to this trend, a beetle with a serrated mandible that cannot survive without parents. However, this exception occurs in a species that has recently evolved the loss of independence.ConclusionsWe argue that the absence of mandible serrations occurs due to alternative selection pressures incurred in larvae dependent upon parents to survive. We suggest that this may have led to a variable function for mandibles, perhaps related to increased competitive ability among siblings or increased efficiency in receiving nutrition from parents. Furthermore, we propose that the phylogenetic pattern we see is consistent with the long‐held evolutionary hypothesis that evolutionary change in behavior and physiology precede morphological change.

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A sustained change in the supply of parental care causes adaptive evolution of offspring morphology

Cited by 34 publications

References 52 publications

Parental care and sibling competition independently increase phenotypic variation among burying beetle siblings

Parental care and sibling competition independently increase phenotypic variation among burying beetle siblings

Adaptive evolution of synchronous egg-hatching in compensation for the loss of parental care

Variation in mandible development and its relationship to dependence on parents across burying beetles

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