Maternal and paternal effects on offspring phenotype in the dung beetle Onthophagus taurus

Parents often have important influences on the development of traits in the ir offspring. One mechanism by which parents are able to influence offsprin g phenotype is through the level of care they provide. In onthophagine dung beetles, parents typically provision their offspring by packing dung fragm ents into a brood mass. Onthophagus taurus males can be separated into two discrete morphs: Large, "major" males have head horns, whereas "minor" male s are hornless. Here we show that a switch in parental provisioning strateg ies adopted by males coincides with the switch in male morphology. Male pro visioning results in the production of heavier brood masses than females wi ll produce alone. However, unlike females in which the level of provisionin g increases with body size in a continuous manner, the level of provisionin g provided by males represents an "all-or-none" tactic with all major males providing a Bred level of provisioning irrespective of their body size. Of fspring size is determined largely by the quantity of dung provided to the developing larvae so that paternal and maternal provisioning affects the bo dy size and horn size of offspring produced. The levels of provisioning by individual parents are significantly repeatable, suggesting paternal and ma ternal effects as candidate indirect genetic effects in the evolution of ho rn size in the genus Onthophagus.