Horizontal gene transfer. (A) Schematic of the location of the sucrose-6-phosphate hydrolase gene (scrB, red arrow) on the male and female scaffolds. Green arrows indicate adjacent gene models with similarity to insect proteins by BLASTx (post-glycosylphosphatidylinositol (GPI) attachment to proteins factor 2-like (pgap2-like) and hypothetical protein, (hypo)). Blue arrows indicate the location of primers used to amplify intergenic regions between horizontal gene transfer (HGT) and adjacent beetle genes. Grey dashed lines indicate the similar gene models on the different scaffolds. (B) Presence of scrB in different beetle species. Green check marks and red Xs indicate presence and absence of the sucrose-6-phosphate hydrolase gene, respectively. Abbreviations: Dfro, Dendroctonus frontalis; Dmic, Dendroctonus micans; Dpon, Dendroctonus ponderosae; Dpun, Dendroctonus punctatus; Ipin, Ips pini; Ityp, Ips typographus; Pstr, Pissodes strobi; Tcas, Tribolium castaneum. Divergence dates estimated from Sequeira and Farrell . (C) Phylogeny of scrB proteins from Dendroctonus (in red) with Gammaproteobacteria scrB and similar insect proteins. Abbreviations: bFF, beta-fructofuranosidase; Bimp, Bombus impatiens; Blic (in purple), Bacillus licheniformis; Bmor, Bombyx mori; Cfre, Citrobacter freundii; Cint, Commensalibacter intestine; Dfro, D. frontalis; Dmic, D. micans; Dpon, D. ponderosae; Dpun, D. punctatus; Eaer, Enterobacter aerogenes; Ebac, Enterobacteriaceae bacterium 9_2_54FAA; Eclo, Enterobacter cloacae; Ecol, Escherichia coli; Esp, Enterobacter sp.; Etas, Erwinia tasmaniensis; Koxy, Klebsiella oxytoca; Kpne, Klebsiella pneumoniae; Ksp, Klebsiella sp.; Kvar, Klebsiella variicola; Pcar, Pectobacterium carotovorum; Pret, Providencia rettgeri; Prus, P. rustigianii; Raqu, Rahnella aquatilis; Rsp, Rahnella sp.; sacC, glycoside hydrolase; scrB, sucrose-6-phosphate hydrolase; Sfle, Shigella flexneri; Sodo, Serratia odorifera; Sply, Serratia plymuthica; Sson, Shigella sonnei; Ssp, Serratia sp.; Yald, Yersinia aldovae; Yent, Yersinia enterocolitica; Yfre, Yersinia frederiksenii; Yroh, Yersinia rohdei. Branches with dots had greater than 80% bootstrap support. The tree was rooted with Bombyx mori beta-fructofuranosidase (Bmor-bFF, in blue).