Genomic and morphological analyses of Asian honeybee subspecies, Apis cerana sanshasis, suggest it's evolutional origin and adaption to island

Abstract

It’s important to discover new resources and expand knowledge of the distribution range of Apis cerana for the conservation and utilization of genetic resources. Here, we newly sequenced genomes and apply population genetic and morphological analysis methods using publicly available genome-wide datasets to investigate the origin and adaptation of A.cerana sanshasis from Yongxing Island. The results showed SanshaId colony was significantly genetically differentiated from others with an average Fst of 0.2669, indicating a level of subspecies differentiation. Morphological clustering also showed significant differences, especially the tongue length of SanshaId colony was significantly smaller than that of others. In summary, we concluded that A.cerana sanshasis is a subspecies of A.cerana. Population history analysis showed SanshaId population has a recent common ancestral feature with Hainan’s, and subspecies differentiation occurred around 0.57 Ma due to geological movements causing geographic isolation. We examined the genetic variation between the recently marginalized colonies from HainanId and SanshaId, and found high frequency nonsynonymous mutations gene in SanshaId colony involved in Glutathione metabolism and other signaling pathways, among which a gene potentially related to tongue length morphology, Cuticular, was subject to evolutionary selection; meanwhile, differential tissue expression profiles showed a correlation with glucose metabolism genes are highly expressed in the midgut, suggesting these genes may be associated with adaptation to tropical island environments. Our results expand the understanding of the distribution range of Asian honeybee and provide the basis for understanding the population dynamics of A.cerana sanshasis and the molecular evolutionary mechanisms of adaptation to tropical island environments.