The unicellular trypanosomatids belong to the phylum Euglenozoa and all known species are obligate parasites. Distinct lineages infect plants, invertebrates, and vertebrates, including humans. Genome data for marine diplonemids, together with freshwater euglenids and free-living kinetoplastids, the closest known nonparasitic relatives to trypanosomatids, recently became available. Robust phylogenetic reconstructions across Euglenozoa are now possible and place the results of parasite-focused studies into an evolutionary context. Here we discuss recent advances in identifying the factors shaping the evolution of Euglenozoa, focusing on ancestral features generally considered parasite-specific. Remarkably, most of these predate the transition(s) to parasitism, suggesting that the presence of certain preconditions makes a significant lifestyle change more likely.

单细胞锥虫属于真眼动物门，所有已知物种均为专性寄生虫。不同的谱系感染植物，无脊椎动物和脊椎动物，包括人类。最近可获得海洋二倍体动物的基因组数据，以及淡水桉树和自由活动的动体，这是与锥虫的亲缘关系最近的非寄生虫亲属。现在有可能在整个裸藻科中进行强有力的系统发育重建，并将以寄生虫为重点的研究结果置于进化背景下。在这里，我们将讨论确定成虫的进化因素的最新进展，重点关注通常被认为是寄生虫特异性的祖先特征。值得注意的是，其中大多数早于向寄生虫过渡，