Variation in allocation toward growth in burying beetles with size determined competitive interactions

Background/Question/Methods

Life-history theory predicts that where energy is limited, there exists a trade-off in which an organism must invest a limited quantity of energy either toward growth in size or toward storage for maintenance and survival. Natural selection will determine which strategy is favored. Burying beetles Nicrophorus orbicollis raise their offspring on small animal carcasses. Competition for carcasses between individuals is common in natural populations.  Such competitive events generally favor larger beetles. Burying beetles show determinant growth and attain maximum size upon emerging as adults from a pupa.  As larger beetles generally show higher reproductive success than smaller beetles, selection could potentially favor increased investment in growth by pupating larva.  However, increased investment in growth would likely come at the cost of energy storage which may be essential for survival in newly emerged beetles.  Therefore, over-allocation to growth could increase mortality and decrease overall fitness. We examine whether there is a correlation between size of larva at dispersal and size at emergence of N. orbicollis beetles.

Results/Conclusions

We find a significant correlation between size at pupation and size at emergence, however, some variation in the amount of energy allocated to growth does occur. We additionally show that  there is heritability with regard to variation in the amount of energy devoted to growth in N. orbicollis.