Water wave communication in the genus Bombina (amphibia)

Amphibians were phylogenetically the first vertebrates to leave the aquatic environment and cope with terrestrial conditions including effects of gravity and substrate on movement and communication. Studies of extant primitive amphibians, which have conserved ancestral morphology and behavior, may help us to understand how gravitational adaptation from aquatic to terrestrial environments occurred. The anuran genus Bombina is a candidate for this type of investigation. In particular, a member of this genus, B. orientalis, is known for its low reaction threshold to minor changes of angular acceleration. We hypothesize that a heightened sensitivity to angular and mechanical accelerations evolved with wave communication. Comparisons of such behavior among B. variegata, B. bombina and B. orientalis may shed light on the evolution of reproductive systems based on water wave communication and relevant vestibular sensitivity. This may represent a transition to derived vocalization modes, which is seen in B. bombina to a certain degree.