Clonemate cotransmission supports a role for kin selection in a puppeteer parasite

Significance The lancet flukeDicrocoelium dendriticum can precisely manipulate its ant host to facilitate transmission to its ungulate host. However, the sole parasite manipulator in the ant brain is presumed not infective to its next host whereas the parasites in the abdomen of the same ant are infective. We conducted a test of genetic relatedness between the brain fluke to those flukes in the abdomen. Our data show that clonemates (i.e. genetically identical individuals) are cotransmitted into ants and that the brain fluke is often a clonemate of flukes in the abdomen. Hence, our study provides empirical evidence that supports a role for kin selection in the evolution of a host-manipulating behavior.