Experimental evolution of multicellularity

• Published in: Proceedings of the National Academy of Sciences - PNAS Vol. 109; no. 5; pp. 1595 - 1600
• Main Authors: Ratcliff, William C, Denison, R. Ford, Borrello, Mark, Travisano, Michael
• Format: Journal Article
• Language: English
• Published: United States National Academy of Sciences 31.01.2012; National Acad Sciences
• Subjects: Apoptosis; Biological Evolution; Biological Sciences; Cell adhesion; Cell division; Cells; Cellular differentiation; determinate growth; Ecological competition; eukaryotic cells; Evolution; Forced migration; Genes, Fungal; Genotype; Genotype & phenotype; Genotypes; labor; life history; new technology; Phenotypes; Physiology; reproduction; Saccharomyces cerevisiae; Saccharomyces cerevisiae - cytology; Saccharomyces cerevisiae - genetics; Yeast; Yeasts
• ISSN: 0027-8424; 1091-6490
• DOI: 10.1073/pnas.1115323109

Multicellularity was one of the most significant innovations in the history of life, but its initial evolution remains poorly understood. Using experimental evolution, we show that key steps in this transition could have occurred quickly. We subjected the unicellular yeast Saccharomyces cerevisiae to an environment in which we expected multicellularity to be adaptive. We observed the rapid evolution of clustering genotypes that display a novel multicellular life history characterized by reproduction via multicellular propagules, a juvenile phase, and determinate growth. The multicellular clusters are uniclonal, minimizing within-cluster genetic conflicts of interest. Simple among-cell division of labor rapidly evolved. Early multicellular strains were composed of physiologically similar cells, but these subsequently evolved higher rates of programmed cell death (apoptosis), an adaptation that increases propagule production. These results show that key aspects of multicellular complexity, a subject of central importance to biology, can readily evolve from unicellular eukaryotes.