Fig. 6.—

Proposed evolutionary scenarios for the establishment of Serratia symbiotica as a co-obligate endosymbiont in currently sequenced Lachninae aphids. Dendogram representing the evolutionary history of Buchnera within aphids and the proposed (A) convergent and (B) nonconvergent scenarios for the establishment of S. symbiotica as a co-obligate endosymbiont in the Lachninae. Blue and red lines represent Buchnera and S. symbiotica, respectively. The blue diagonal lines represent losses in Buchnera, while the red diagonal lines represent those in S. symbiotica. Names on top and below of branches indicate the aphid familiar name (bold) and tribal name. Scale bar at the bottom represents timing in Ma for the branching of the different aphids. IN, infection events; Replace, symbiont replacement events; GRed, Genome reduction events; trpEGloss, trpEG gene-loss events.