Context-dependent kin discrimination in larval four-toed salamanders Hemidactylium scutatum (Caudata: Plethodontidae)

We studied kin discrimination in the larvae of the four-toed salamander Hemidactylium scutatum. The results of a spatial affinity assay supported the hypothesis that larvae can recognize kin and do so whether they have been raised alone or with siblings. Larvae were attracted to siblings and did not avoid non-siblings. Two additional experiments tested the hypothesis that kin discrimination is a function of predator density. The consistent predator avoidance pattern of larval H. scutatum was to lower activity level. In the experiment characterized by a higher predator density, sibling groups of larvae exposed to a predator lowered their amount of swimming more than larvae in mixed sibling groups. These results are consistent with the hypothesis of context-dependent kin discrimination and suggest that individuals can balance costs and benefits of behaviors as a function of ecological and social factors. This study is the first to demonstrate kin recognition in the larval stage of any species in the family Plethodontidae.