Figure 1.

The role of PCD in ETIs. PCD plays several roles in evolutionary transitions in individuality. (A) PCD is a mediator of conflict by aligning the evolutionary fate of individuals in the social group (the eukaryote cell in this example). (B) PCD is essential for the propagation and dispersal of colonies (see the discussion on Trichodesmium). (C) PCD is a mechanism by which fitness is transferred from the lower to the higher individual (see the examples of Chlamydomonas, Saccharomyces, and Dictyostelium). (D) PCD is a form of division of labor in social groups (see the discussion on Dictyostelium).