Fig. 3.

Summary of the gains and losses of heritable symbionts across sap-feeding insects in the order Hemiptera. The phylogenies show evolutionary relationships of host insect groups (gray) and heritable symbionts. For color-coded lines, see Inset legend. Host phylogeny represents the most recent understanding, but placement of certain lineages (e.g., the Coleorrhyncha and Heteroptera) is uncertain (12, 89). Ancestral symbiont names are in boxes along their lineage; in some cases, the same symbiont lineage has different names in different insect clades. Names of acquired symbionts are shown where the symbiont is acquired on the host phylogeny. Dashed lines represent hypothetical relationships and possible origins of symbiosis deep in the evolution of the Hemiptera. The white-dashed lineage represents an ancestral symbiont that permitted the initial diversification of the Hemiptera; its identity is not yet known. Lineages that terminate at a question mark remain uncertain; host–symbiont relationships in these clades are diverse and their origins unclear. See text for citations regarding specific symbionts presented on the tree.