Geographic distribution of the eastern honeybee, Apis cerana (Hymenoptera: Apidae), across ecological zones in China: morphological and molecular analyses.

摘要

The biogeography and intraspecific variability of the eastern cavity-nesting honeybee, Apis cerana, are not very well known. We studied the variability of this species in China using morphometrical methods together with restriction and sequence analysis of two different regions of mitochondrial DNA. Samples of A. cerana were collected from feral or traditionally managed colonies in 19 locations of the Chinese mainland, covering the main ecological regions. Worker bees from each sample were dissected and morphometric characters were measured. The data were analysed with multivariate statistical procedures. Data were supplemented by previously published Chinese samples from the Oberursel data bank and reference samples of A. cerana from adjacent countries. A mitochondrial DNA fragment containing a non-coding region was amplified and analysed with the restriction enzyme DraI. This fragment was sequenced for two samples. For a subset of samples, the subunit 2 of the mitochondrial NADH gene was amplified and sequenced. Morphometric analysis revealed a high degree of variation, strongly associated with ecological zones and correlated with geographical and climatic parameters. Two main clusters were apparent, one comprised the bees from the southern tropical seasonal rain forest region, showing strong associations to the bees of Vietnam, Thailand and Myanmar. The second main cluster included the bees from the temperate deciduous broad-leaved forest region, the subtropical evergreen broad-leaved forest zone, the high, cold meadow and steppe region and the North, and showed increasing similarity to the bees of Korea and Japan. In particular, the bees from Qingzang plateau, on the fringe of the Ganshu province, were set apart by their exceptional body size, darkness and pilosity. There was no variation in DraI restriction patterns within China. Sequence variation of the mitochondrial ND2 region was consistent with geographic patterns of morphological variation. Bees of the South Yunnan region were set apart by characteristically broad abdominal sterna and wax mirrors, with this locally restricted trait transcending the main transition line at the northern limit of the tropical seasonal rain forest region. This northern limit appears to correspond to the separation line between A. cerana indica and A. cerana cerana..