Mechanisms and ecological correlates of kin recognition.

Kin recognition, which can be inferred from differential interactions amongst close relatives as compared to unrelated conspecifics, has been documented in a wide range of vertebrates and invertebrates. Kin may be discriminated by phenotypic traits (signatures) that are genetically mediated, acquired from the environment, or arise from an interaction between these two sources. The developmental mechanisms underlying recognition of relatives (or their signatures) include direct contact and familiarization, indirect familiarity (whereby previously unencountered individuals are recognized by their resemblance to familiar kin) and hypothetical recognition alleles. The biological significance and mediating mechanisms of kin recognition vary across species according to their ecology and natural history. To illustrate this point, the results of laboratory and field studies of larvae of several species of toads and frogs are reviewed.