Timing of oviposition and reproductive skew in cobreeding female burying beetles (Nicrophorus vespilloides)

Burying beetles (genus Nicrophorus) are known for their elaborate parental care. Two or more conspecific females may reproduce on the same carcass, es pecially when the carcass is large. Here we present the results of experime nts in which we observed patterns of larval hatching and parental care in u nmanipulated cobreeders, manipulated hatching synchrony between cobreeders, and compared patterns of oviposition in cobreeding and single females. Our results show that in these cobreeding associations, one of the females may or may not monopolize the carcass during the period of larval hatching. We present evidence that in either case, infanticide based on temporal cues c onstitutes an important proximate mechanism underlying the observed reducti on in average reproductive success in cobreeding females. Females with high er synchrony (i.e., greater overlap between their oviposition patterns) pro duce larger broods with lower reproductive skew. Cobreeding females oviposi t later and less synchronously than single breeders. Such delayed ovipositi on may reduce the risk that a female's larvae fall victim to cannibalistic acts committed by her cobreeder or maximize her own opportunity to selectiv ely kill her cobreeder's larvae.