Association preference and mechanism of kin recognition in tadpoles of the toad Bufo melanostictus.

ABSTRACT

In experiments with specially designed choice tanks, tadpoles of Bufo melanostictus spend signifi cantly greater amounts of time near kin than near non-kin. However, in the absence of kin members, they prefer to spend more time near non-kin rather than stay away in isolation in the opposite blank zone with no company. This implies that association of toad tadpoles with their kin is due to attraction rather than repulsion from non-kin. Experiments designed to elucidate the sensory basis of kin recognition showed that toad tadpoles recognize their kin based on chemical cues rather than visual cues. They can also discriminate between homospecifi c non-kin and heterospecifi c (Sphaerotheca breviceps) tadpoles since the tadpoles spent signifi cantly greater amounts of time near the former than near the latter. These fi ndings suggest that where kin members are unavailable, selection may have favoured living with non-kin so as to derive benefi ts from group living and that a phenotype-matching mechanism may operate for both kin and species discrimination in B. melanostictus.