We investigated the costs of building and maintaining this spherical carcass nest, in relation to any benefits that might be gained by the larvae from its spherical nature or ‘sphericity’.Ī perfect sphere of flesh creates the lowest possible surface area to volume ratio of the carcass, which could have several associated advantages for the parents.
Beetles also defend carcasses from microbial decay by smearing them with antimicrobial exudates 8, 9 and this imposes a fitness cost on the parents 10. This becomes an edible nest, which nourishes and houses the developing larvae 7. Within two days they transform the carcass into a naked ball of flesh. They roll the flesh into a ball by sinking it below ground and repeatedly thrusting it against a tunnel wall, turning it between thrusts 6. Here we use these methods to determine whether the costs of nest-building and maintenance are correlated with natural variation in burying beetle nest architecture.īurying beetles ( Nicrophorus vespilloides) prepare the carcass of a small vertebrate for reproduction by removing any fur or feathers.
The advantage of each of these approaches is that the costs of nest-building can be estimated without quantifying details of the behaviour involved (see also 5). A different technique for quantifying costs is to measure an individual’s residual fitness after nest construction or maintenance: the lower its residual fitness, the greater the cost it has incurred through its nesting activity. If there are costs involved, however, only the highest quality parents should be able to build this ideal nest. If constructing a nest is entirely cost-free, then all parents should be able to construct an ‘ideal’ nest, irrespective of their quality. One approach is to seek a correlation with parental quality. Just as with other behavioural traits 4, the costs associated specifically with nest-building can be exposed in different ways. Although it is clear how some aspects of nest architecture function to promote successful reproduction 1, 2, 3 it has been much harder to isolate elements of nest design that are linked to the costs borne by parents of nest construction and maintenance. Specifically, natural selection is predicted to favour designs that enhance reproductive success while minimising building and maintenance costs to parental fitness 1, 2, 3. Nest-building is widespread among animals, and the extraordinary diversity in nest architecture is thought to be adaptive 1.
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