entamoeba invadens found that, during the conversion from the tetraploid uninucleate trophozoite to the tetranucleate cyst, homologous recombination is enhanced. expression of genes with functions related to the major steps of meiotic recombination also increase during encystations. these findings in e. invadens, combined with evidence from studies of e. histolytica indicate the presence of meiosis in the entamoeba. dictyostelium discoideum in the supergroup amoebozoa can undergo mating and sexual reproduction including meiosis when food is scarce. since the amoebozoa diverged early from the eukaryotic family tree, these results suggest that meiosis was present early in eukaryotic evolution. furthermore, these findings are consistent with the proposal of lahr et al. that the majority of amoeboid lineages are anciently sexual.