Investigation of Matrilineal Relationships via Mitochondrial DNA in the Southeastern Yellowjacket (Vespula squamosa)

The question of whether and how apparently "altruistic" behaviors can evolve in social animals has received an enormous amount of attention from evolutionary biologists and has been termed "the central theoretical problem of sociobiology". Thus, recent interest is eusocial species with coexisting multiple queens stems from the realization that the genetic relatedness of individuals in such colonies presents additional theoretical challenges beyond those addressed by the Hamiltonian model of kin selection and lengthens the potential list of reproductive conflicts of interest. The Southeastern Yellowjacket (Vespula squamosa) exhibits two social forms sympatrically in the southern parts of its range. These two social forms differ with respect to queen number and are termed monogyne (single queen) and polygyne (multiple queens). Since multiple functional queens within a colony affects offspring relatedness, inclusive fitness theory predicts that polygyne colonies are more likely composed of cooperating sister queens. Therefore, this study tested the Hamiltonian model by investigating matrilineal relationships within polygyne colonies to discern if coinhabiting queens were sisters or unrelated individuals. Six hundred and twenty-seven base pairs of the Cytochrome B (Cyt B) gene within the mitochondrial DNA (mtDNA) was sequenced for 13 to 15 queens from 10 polygyne colonies and one worker from 17 monogyne colonies. The Cyt B gene of V. squamosa has a similar AT content (77%) as that found in other Hymenoptera and other taxa in the Insecta. In addition, the Cyt B gene of V. squamosa had the greatest similarity to the Cyt B genes of other insects. The sequence similarity to other vespid Cyt B genes, however, was less than that of the Honey Bee, Apis mellifera. Sequence analysis showed that there was no variation within this region of the mtDNA of V. squamosa and this region, therefore, could not resolve relatedness among individuals. Possible reasons for the lack of genetic variation and the unusual sequence divergence are discussed.