Assessment of gains and losses of lateral gene transfer (LGTs) during parasite speciation. Maximum parsimony was used to map candidate LGTs on the species trees for taxa among (a) Trypanosomatidae and (b) Apicomplexa. Gains and losses are indicated as green and orange bars respectively. Characters were analyzed using Dollo parsimony, so each character is allowed to have only a single gain, but may have multiple losses. It is inferred that 45 LGTs occurred (over 75 genes affected by LGT) before the divergence of the three Trypanosomatidae lineages. Fewer (7/75) LGTs are specific to the individual Trypanosoma spp. lineages, whereas the branch to L. major is inferred to have experienced 22 gains after splitting from Trypanosoma. The reference phylogeny for the Apicomplexa used to map the LGTs is from Wasmuth et al. . Four LGTs were inferred to been gained by the common ancestors of all sampled apicomplexans. Losses of two and four LGTs were inferred for Toxoplasma gondii and Plasmodium yoelii yoelii, respectively. Additional LGTs were inferred across the other branches, clearly indicating the dynamic nature of LGTs during the diversification of these parasites.