Genomic signatures of introgression between commercial and native bumblebees, Bombus terrestris, in western Iberian Peninsula—Implications for conservation and trade regulation

Human‐mediated introductions of species may have profound impacts on native eco ‐systems. One potential impact with largely unforeseen consequences is the potential admixture of introduced with autochthonous species through hybridization. Throughout the world, bumblebees have been deliberately introduced for crop pol ‐lination with known negative impacts on native pollinators. Given the likely alloch ‐thonous origin of commercial bumblebees used in Portugal (subspecies Bombus terrestris terrestris and B. t. dalmatinus), our aim was to assess their putative introgres‐sion with the native Iberian subspecies B. terrestris lusitanicus. We analysed one mito ‐chondrial gene, cytochrome c oxidase subunit I (COX1) and genomic data involving thousands of genome‐wide restriction‐site‐associated DNA markers (RAD‐seq). In the mitochondrial COX1 analyses, we detected one relatively common haplotype in commercial bumblebees, also present in wild samples collected nearby the green ‐houses where the commercial hives are used. In the RAD‐seq analysis, we found a clear genetic differentiation between native and commercial lineages. Furthermore,we detected candidate hybrids in the wild, as well as putatively escaped commercialbumblebees, some of which being potentially fertile males. Although we cannot as ‐sess directly the fitness effects of introgressed alleles, there is a risk of maladaptive allele introgression to the local bumblebee subspecies, which can negatively impact autochthon populations. One immediate recommendation to farmers is for the proper disposal of hive boxes, after their use in greenhouses, so as to minimize the risk of escapees contaminating native populations. On the other hand, the feasibilityof using local subspecies B. t. lusitanicus, preferably with local production, should be evaluated.

URI

http://hdl.handle.net/10451/60850

Citation

Seabra SG, Silva SE, Nunes VL, et al.Genomic signatures of introgression between commercial andnative bumblebees, Bombus terrestris, in western IberianPeninsula—Implications for conservation and trade regulation.Evol Appl. 2019;12:679–691. https://doi.org/10.1111/eva.12732