Kin recognition and sibling association among wood frog (Rana sylvatica) tadpoles

Abstract

1. Wood frog (Rana sylvatica) tadpoles, hatched from egg masses collected in the field, were reared either with siblings only or in mixed groups of eight sibships. Sibships were marked with vital stains, released in a laboratory test pool, and their spatial distributions recorded over a 4-day period. 2. An analysis of nearest-neighbor distances suggests that tadpoles preferentially associated with familiar siblings over both familiar and unfamiliar non-siblings. Kinship preferences of R. sylvatica tadpoles, unlike those of other anurans that have been tested, thus appear largely unaffected by prior social experience. 3. Tadpoles reared in mixed sibship groups preferentially associated with the siblings with which they were reared over unfamiliar siblings exposed to a different set of sibships. In contrast, tadpoles did not discriminate either between siblings reared in different baskets within the same mixed group tank, or between siblings housed in different singlesibship containers. 4. Because R. sylvatica egg masses are usually deposited in communal clumps, an ability to recognize relatives not dependent on post-embryonic experience may have been selected. The possible adaptive significance of kin association among wood frog tadpoles is unknown; their schools probably do not represent kin groups, but larval distributions in natural ponds might reflect sibling association tendencies. 5. Kin recognition “labels” of non-sibling R. sylvatica tadpoles reared together, like those of R. cascadae tadpoles similarly reared, may converge as a result of social interactions. R. sylvatica tadpoles, unlike R. cascadae tadpoles, retain an ability to discriminate between familiar siblings and familiar non-siblings; hence label transference may be incomplete.