Adaptive evolution of honeybee dance dialects.

Efficient communication is highly important for the evolutionary success of social animals. Honeybees (genus Apis) are unique in that they communicate the spatial information of resources using a symbolic 'language', the waggle dance. Different honeybee species differ in foraging ecology but it remains unknown whether this shaped variation in the dance. We studied distance dialects-interspecific differences in how waggle duration relates to flight distance-and tested the hypothesis that these evolved to maximize communication precision over the bees' foraging ranges. We performed feeder experiments with Apis cerana, A. florea and A. dorsata in India and found that A. cerana had the steepest dialect, i.e. a rapid increase in waggle duration with increasing feeder distance, A. florea had an intermediate, and A. dorsata had the lowest dialect. By decoding dances for natural food sites, we inferred that the foraging range was smallest in A. cerana, intermediate in A. florea and largest in A. dorsata. The inverse correlation between foraging range and dialect was corroborated when comparing six (sub)species across the geographical range of the genus including previously published data. We conclude that dance dialects constitute adaptations resulting from a trade-off between the spatial range and the spatial accuracy of communication.