Taxonomy of donor lineages for candidate lateral gene transfer (LGTs). (a) Donor lineages for LGTs were defined as the adjacent (as defined by Wilkinson et al. ) prokaryote to our target eukaryote(s) in trees where the relevant eukaryote(s) were separated from other eukaryotes by at least one well-supported node. Complete lists of donor lineages and the corresponding phylogenies are presented (see Additional file 13; see Additional file 5). (b) Taxonomic diversity of donor lineages and their contributions to LGTs. The red bars represent the proportion (%) of protein sequences identified as LGTs per donor lineage compared with the blue bars that show the proportion (%) of sequences from that lineage in the reference dataset used as the search space for the analyses. The relative significance of over-representation or under-representation established by a hypergeometric test is indicated. (c) Comparison of the prokaryotic lineages inferred to be donating genes to the extracellular mucosal parasites Entamoeba histolytica, Trichomonas vaginalis, and Giardia lamblia compared with the inferred donor lineages for the insect-transmitted blood parasites Trypanosoma brucei, Trypanosoma cruzi, Plasmodium falciparum, Plasmodium vivax and Plasmodium yoelii yoelii. (d) Comparison of the prokaryotic lineages inferred to be donating genes to the parasite E. histolytica and its free-living amoebozoan relative Dictyostelium discoideum. (c, d) 'Other bacteria' comprise the Actinobacteria, Aquificae, Fusobacteria, Plantomycetes, Spirochaetes, or Tenericutes. Fisher's exact test was performed to test the null hypothesis that the taxonomy of the donors is distributed equally between the compared taxa. The P-values for the tests are indicated; they both reject the null hypothesis. The numbers of LGTs considered for each set of taxa are indicated between brackets. Complete diagrams showing all categories, including the unresolved 'Bacteria' donors and the different donors summarized as 'other bacteria,' are also presented (see Additional file 12).