Genetic control for sibling recognition?

The ability to distinguish between kin and non-kin is critical to current theories of altruistic behaviour and kin selection. Hamilton predicted that individuals would behave differently towards one another depending on the genetic relatedness between them. When either proximity to or familiarity with kin is a good predictor of relatedness, the mechanism by which favouritism towards kin is accomplished may not require special kin recognition abilities. However, if proximity and familiarity are poor predictors of kinship, favouritism (hence increases in inclusive fitness) could only be achieved by the differential recognition of kin and non-kin. We have previously shown that Cascades frog (Rana cascadae) tadpoles reared with siblings prefer to associate with siblings over non-siblings. The present study is the first to report that totally naive individuals (R. cascadae tadpoles) prefer to associate with siblings over non-siblings. Because tadpoles were separated before hatching and reared apart from other individuals, results suggest that the ability of these tadpoles to discriminate between siblings and non-siblings has some innate component.