Matt Schrader and collaborators at the University of Cambridge have published a paper titled Cooperative interactions within the family enhance the capacity for evolutionary change in body size in Nature Ecology and Evolution examining how cooperation among family members influences the evolution of body size. The study combined artificial selection on lab populations of the burying beetle, Nicrophorus vespilloides, with comparative data from many other species of Nicrophorus to ask how parental care influences the potential for evolutionary change. Beetles in this genus rely on vertebrae carrion to breed and display remarkably complex parental care.
Selection for large body size only resulted in evolutionary change when beetle parents were allowed to care for their young. In contrast, selection for small body size was only successful when parents were prevented from caring for their larvae. In addition, the authors found a strong positive correlation between the importance of parental care and body size among different species of Nicrophorus. Specifically, large species require parental care whereas small species can survive without it. These results suggest that evolutionary increases in body size are intimately tied to cooperative interactions among parents and offspring.