Does sibling competition have a sex-specific effect on offspring growth and development in the burying beetle Nicrophorus vespilloides?

During offspring growth, reduction in resource availability through competitive interactions will restrict how large individuals can become. Given that selection to mature at a large size will be greater for the sex in which large size provides the highest fitness return, sex-specific differences in response to a decrease in resource availability may be expected. Using Nicrophorus vespilloides Herbst (Coleoptera: Silphidae) we examined the sex-specific response of offspring to resource availability through sibling competition. We found that males and females were affected similarly by an increase in the level of sibling competition as brood size increased. Interestingly, although male N. vespilloides were consistently heavier than females, over a range of brood sizes, they were only significantly heavier than females at intermediate brood sizes. At present, the causes behind this finding remain unclear. © 2008 The Authors.