Genetic structure of drone congregations of the stingless bee Scaptotrigona mexicana

Abstract.

Drones of stingless bee species often form distinctive congregations of up to several hundred individuals which can persist over considerable periods of time. Here we analyse the genetic structure of three drone congregations of the neotropical stingless bee Scaptotrigona mexicana employing eight microsatellite markers. Two congregations were close to each other (50 m), the third one was located more than 10 km away from them. This spatial pattern was also reflected on the genetic level : the two close congregations did not show any population sub-structuring, whereas the more distant congregation showed a significant population differentiation to both of them. Population subdifferentiation was however low with F _st values (F _st = 0.020 and 0.014) between the distant congregations, suggesting gene flow over larger distances mediated by the drones of S. mexicana. Based on the genotypic data we also estimated the number of colonies contributing drones to the congregations. The two joint congregations consisted of drones originating from 39,6 colonies, while the third congregation was composed of drones from 21,8 colonies, thus proving that congregations of S. mexicana are constituted of unrelated drones of multicolonial origin.