Whole-genome Resequencing Provides Insights Into The Population Genetic Structure And Adaptation Of Bumblebee Bombus Terrestris

Bumblebees(genus Bombus)are ecologically and economically important pollinating insects,with～250 extant species worldwide,serving as the sole or predominant pollinators of large numbers of wild plants.They were well known as excellent pollinators of greenhouse tomato crops,decreasing the cost of labor and improving the yield and quality of the fruits.Bumblebee pollination services are available in the United States,with an annual economic value of $1.25 billion.The declines of bumblebees in abundance and distribution resulting from global and local environmental changes will threaten pollination services to both wild plants and crops,raising concerns for bumblebees,food security,and ecosystem stability.The buff-tailed bumblebee,Bombus terrestris(L.1758),is one of the most widely used pollinator species for greenhouse crop pollination,which has been artificially reared by commercial companies in the 1980 s.B.terrestris is a broadly distributed species and exposed to diverse climatic conditions,which makes it a good model to study population differentiation and adaptation.In many countries,it was discovered that B.terrestris caused invasion in the process of import and use,which seriously affected the local ecological balance and diversity.As the largest country in facility horticulture,China has a huge demand for bumblebee pollination services.However,China do not have domesticated bumblebee species capable of large-scale commercial pollination.we performed whole-genome resequencing on these 67 samples and employed population genomic and bioinformatic methods to infer the population genetic structure and identify candidate genes involved in B.terrestris adaptation.The mainly research contents of this paper are as follows:1.Whole-genome resequencing on 67 B.terrestris samples,including 14 domesticated samples and 63 wild samples,and 905 Gb original data were generated.2.Through sequence alignment and population variation detection,a total of 4,827,687 SNPs and615,899 InDels were obtained,with an average of 19.42 SNPs and 2.47 InDels per 1 kb in the genome,constructed the biggest genetic variation map of B.terrestris.3.Population structure and gene flow analysis found that B.terrestris samples were divided into Asia population and Europe population,Europe population also can be divided into wild pop and domestic pop,and the samples from China were determined to be the native bumblebee specie.This also filled the gap in the study of Asia B.terrestris.4.Infer the relationship between demographic history of B.terrestris populations and climate change,we found that B.terrestris can still maintain growth in cold climate,and speculated that the separation of the Asia population and Europe population was caused by the beginning of the Penultimate Glaciation about 300,000 years ago.5.Identify selected regions and functional genes in the genome of B.terrestris under the influence of different natural environments in Asia.Found a large number of genes related to environmental adaptability such as low temperature and strong ultraviolet radiation with gene enrichment analysis.6.Identified selected regions and functional genes associated with artificial selection during the domestication of B.terrestris.Found a large number of genes related to single food and no light in environment were found with gene enrichment analysis.7.Using the fixed genetic variations between domesticated and wild B.terrestris as molecular markers,establish a molecular biology method to distinguish between invading domesticated B.terrestris and native wild B.terrestris.