Species where, from birth, the offspring feed themselves in addition to begging for food from the parents can be described as 'partially begging'. Such species provide a unique opportunity to examine the evolution of offspring begging from non-signalling offspring foraging strategies. We used the partially begging burying beetle Nicrophorus vespilloides to test specific hypotheses concerning the coexistence of begging and self-feeding. We first tested whether the cessation of larval begging coincided with an increase in the efficiency of self-feeding. As predicted, begging ceased when the efficiency of self-feeding reached the point where the larvae grew just as well without as with access to food provided by the parent. We next tested whether the transition to nutritional independence was under parental or offspring control. The parent did not change its behaviour towards the larvae over time, while the larvae changed their behaviour by reducing the time spent begging in the presence of the parent. Food allocation during the transition to nutritional independence was therefore under offspring control. Our results on partial begging provide a starting point for new theoretical models for the origin of begging. We suggest that these should be constructed as scramble-competition models because the offspring control food allocation.
Very few studies have examined parent-offspring interactions from a quantitative genetic perspective. We used a crossfostering design and measured genetic correlations and components of social selection arising from two parental and two offspring behaviors in the burying beetle Nicrophorus vespilloides. Genetic correlations were assessed by examining behavior of relatives independent of common social influences. We found positive genetic correlations between all pairs of behaviors, including between parent and offspring behaviors. Patterns of selection were assessed by standardized performance and selection gradients. Parental provisioning had positive effects on offspring performance and fitness, while remaining near the larvae without feeding them had negative effects. Begging had positive effects on offspring performance and fitness, while increased competition among siblings had negative effects. Coadaptations between parenting and offspring behavior appear to be maintained by genetic correlations and functional trade-offs; parents that feed their offspring more also spend more time in the area where they can forage for themselves. Families with high levels of begging have high levels of sibling competition. Integrating information from genetics and selection thus provides a general explanation for why variation persists in seemingly beneficial traits expressed in parent-offspring interactions and illustrates why it is important to measure functionally related suites of behaviors.
Rich and ephemeral resources, such as carrion, are a source of intense interspecific competition among animal scavengers and microbial decomposers. Janzen [Janzen DH (1977) Am Nat 111:691-713] hypothesized that microbes should be selected to defend such resources by rendering them unpalatable or toxic to animals, and that animals should evolve counterstrategies of avoidance or detoxification. Despite the ubiquity of animal-microbe competition, there are few tests of Janzen's hypothesis, in particular with respect to antimicrobial strategies in animals. Here, we use the burying beetle Nicrophorus vespilloides, a species that obligately breeds on carcasses of small vertebrates, to investigate the role of parental care and avoidance as antimicrobial strategies. We manipulated competition between beetle larvae and microbes by providing beetles with either fresh carcasses or old ones that had reached advanced putrefaction. We found evidence for a strong detrimental effect of microbial competition on beetle reproductive success and larval growth. We also found that parental care can largely compensate for these negative effects, and that when given a choice between old and fresh carcasses, parents tended to choose to rear their broods on the latter. We conclude that parental care and carcass avoidance can function as antimicrobial strategies in this species. Our findings extend the range of behavioral counterstrategies used by animals during competition with microbes, and generalize the work of Janzen to include competition between microbes and insects that rely on carrion as an obligate resource for breeding and not just as an opportunistic meal.animal-microbe interactions ͉ parental care ͉ resource competition
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.