Collective phenotypes, which arise from the interactions among individuals, can be important for the evolution of higher levels of biological organization. However, how a group’s composition determines its collective phenotype remains poorly understood. When starved, cells of the social amoeba Dictyostelium discoideum cooperate to build a multicellular fruiting body, and the morphology of the fruiting body is likely advantageous to the surviving spores. We assessed how the number of strains, as well as their genetic and geographic relationships to one another, impact the group’s morphology and productivity. We find that some strains consistently enhance or detract from the productivity of their groups, regardless of the identity of the other group members. We also detect extensive pairwise and higher-order genotype interactions, which collectively have a large influence on the group phenotype. Whereas previous work in Dictyostelium has focused almost exclusively on whether spore production is equitable when strains cooperate to form multicellular fruiting bodies, our results suggest a previously unrecognized impact of chimeric co-development on the group phenotype. Our results demonstrate how interactions among members of a group influence collective phenotypes and how group phenotypes might in turn impact selection on the individual.

This dataset consists of measures of fruiting body morphology (fruiting body height, sorus diameter), the number of fruiting bodies, and the number of spores produced when mixes of one to six strains of Dictyostelium discoideum are co-developed. Included in the data package are the fruiting body images, data tables containing the results of image analysis and spore counts, and scripts for analysis.

Scripts consist of R markdown files.