Experimental evolution of multicellularity.
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.
Department of Ecology, Evolution and Behavior, University of Minnesota, Minneapolis, MN 55108, USA. ratcl009@umn.edu
William C
WC
Ratcliff
R Ford
RF
Denison
Mark
M
Borrello
Michael
M
Travisano
D017209:Apoptosis; D005075:Biological Evolution; D005800:Genes, Fungal; D005838:Genotype; D012441:Saccharomyces cerevisiae / Q000166:cytology* / Q000235:genetics