Clonality and gall cohabitation in Tamaila coweni

Populations of the Manzanita leaf gall aphid Tamalia coweni in Northern California have exhibited an unusual willingness to co-habitate within their leaf galls, increasing overall reproduction per gall but lowering individual reproductive fitness. A potential explanation for this behvior is that the cohabiting individuals are clones produced in an earlier, asexual reproductive phase and thus the individuals within the gall who share the same genotype are functioning as a single reproductive unit. To test the relatedness of cohabiting individuals, DNA was isolated from individual aphids found within the same gall and subjected to PCR-AFLP analysis. The results produced genetic profiles of high similarity for cohabiting aphids, supporting the hypothesis that the individuals share the same genotype. This data, along with the discovery of "soldierly" morphs in local populations, indicates a possible trend towards eusociality in these organisms.