Pune, August 12, 2011: The European paper wasps, Polistes dominulus, build their nests, where usually a dominant female - the queen - lays the eggs, and several subordinate females do the job of nursing the brood. The behavior of the subordinate females, who are themselves capable of raising their own brood, but instead choose to help raise the brood of another female, has been considered altruistic. A recent study by Dr. Ellouise Leadbeater and other researchers from the University of Sussex, University of Sheffield and the University College London, shows that this apparent 'altruistic' behavior is actually an act in 'self-interest'. The researchers published their findings in a paper* in the latest issue of Science. Following is reproduced from the Public release dated August 12, 2011 by EurekAlert.
*Reference cited: Leadbeater, E., Carruthers, J.M., Green, J.P., Rosser, N.S. and Field, J. 2011. Nest inheritance is the missing source of direct fitness in a primitively eusocial insect. Science 333 (6044): 874-876. DOI:10.1126/science.1205140
EurekAlert Public release date: 12-Aug-2011
'Altruistic' wasps actually looking out for number one
What motivation could animals like the social wasp Polistes dominulus have to work together and help each other out? Until now, researchers have assumed that such cooperative behavior must provide some sort of benefit to the individuals' relatives in order to make the toil worthwhile. But, a new study of these wasps shows that the social insects don't serve their queen for the benefit of their kin. Instead, they receive direct fitness benefits -- and a chance to inherit the throne -- if they stick with the group rather than set out on their own. These findings suggest that individual selection might be enough to explain many instances of social behavior in nature. Ellouise Leadbeater and colleagues explain that each spring, female Polistes wasps, or foundresses, begin building nests on their own or with a group of co-foundresses. In co-founded nests, many of the wasps are completely unrelated, which makes it unclear why they would help the group. So, these researchers performed a large field study in Spain, measuring the reproductive success of 1,113 foundresses -- including dominant queens and subordinate workers -- from 228 different wasp nests. They found that co-foundresses, who were subordinate to the queen, generally produced more offspring than the solitary foundresses, who chose to establish nests on their own. Some of the co-foundresses' offspring were born after inheriting the throne when the queen had died. According to Leadbeater and her team, even the number of offspring from subordinate co-foundresses who did not inherit the queen's position could equal or exceed the number of offspring born from lone foundresses. In light of these findings, it seems like the behavior of these Polistes wasps is not altruistic after all. And, the benefits of inheriting the queen's position may help to explain the evolution of cooperation among these social insects. A Perspective by Raghavendra Gadagkar explains the study in greater detail.