Paper wasps (Polistes fuscatus) are very good at recognizing and remembering individual faces. In the spring, sexually mature females, known as “foundresses,” race to secure a nest site which they may maintain either alone or alongside a coterie of co-foundresses with whom they share brood space. For a given foundress to cooperate with her allies and thwart potential usurpers, she must be able to recognize individual wasps as distinct entities.
The most thoroughly studied populations of paper wasps are those in and around Ann Arbor, Michigan and Ithaca, New York. Wasps from both locations show a striking amount of diversity in facial markings and possess the ability to learn and remember individual faces. Recently, a new population was discovered in Rothrock, Pennsylvania in which individuals seem to lack the highly variable face patterning present in the NY and MI populations. Is this observation an indication that this population lacks the ability to recognize individuals in the way that other populations do?
In their study, Elizabeth Tibbetts and her team of researchers from the University of Michigan found that the Pennsylvania population does exhibit far less variation in facial markings than the Michigan wasps. By measuring social interactions between familiar and unfamiliar social partners, they discovered no evidence that the Pennsylvania wasps remember other individuals. Furthermore, when subjected to a learning assay, the Pennsylvania population appeared to be incapable of learning to distinguish faces while the Michigan population learned to do so very quickly. They also demonstrated that Pennsylvania population was genetically distinct from the Michigan population, which they attributed to the geographic distance between them.
It is unclear whether or not the Pennsylvania population has lost the high level of facial pattern variation and individual recognition that has made P. fuscatus famous, or failed to acquire it. What is clear, however, is that paper wasp communication systems are capable of rapid evolution and can vary even within a species.