Kin recognition by tadpoles and froglets of the wood frog Rana sylvatica

We investigated kin recognition by the wood frog Rana sylvatica in blind laboratory experiments using spatial proximity as a recognition assay. Tadpoles were tested for the ability to discriminate between: 1) familiar full-sibs and unfamiliar non-kin, 2) unfamiliar paternal half-sibs and unfamiliar non-kin, and 3) familiar and unfamiliar full-sibs. Tadpoles discriminated full- and paternal half-sibs from unrelated conspecifics, but did not discriminate between familiar and unfamiliar full-sibs. Froglets from the same laboratory population were tested for the ability to discriminate between 1) familiar full-sibs and unfamiliar non-kin, and 2) unfamiliar paternal half-sibs and unfamiliar non-kin. Froglets preferentially associated with full- and half-sibs over unrelated conspecifics. Our results show that familiarity, i.e., prior association, is not necessary for kin recognition in tadpoles and froglets. The ability of tadpoles and froglets to recognize unfamiliar paternal half-sibs demonstrates that a common maternal factor is not necessary for kin recognition, and indicates that the recognition cue has a genetic component. Our results add to the increasing evidence that a variety of vertebrate and invertebrate animals have the ability to recognize unfamiliar kin by using genetically specified recognition cues.