Abstracts (first author)
Relatedness and the evolution of multicellularity
It has been argued that a high genetic relatedness (r) between cells played a pivotal role in the evo-lutionary transition from single-celled to multicellular organisms. We tested this hypothesis with a comparative study, comparing the form of multicellularity in species where groups are clonal (r = 1), to species where groups are potentially non-clonal (r ≤ 1). We found that: (1) only species with clonal group formation have undergone the major evolutionary transition to obligate multicellularity; (2) clonal organisms had more cell types, a higher likelihood of sterile cells and a trend towards higher numbers of cells in a group. More generally, our results build upon previous studies of animals, to show how group formation and genetic relatedness have played analogous roles in the three evolutionary transitions to multicellularity, cooperative breeding and eusociality.