RT Journal Article SR Electronic T1 De novo origins of multicellularity in response to predation JF bioRxiv FD Cold Spring Harbor Laboratory SP 247361 DO 10.1101/247361 A1 Matthew D. Herron A1 Joshua M. Borin A1 Jacob C. Boswell A1 Jillian Walker A1 I-Chen Kimberly Chen A1 Charles A. Knox A1 Margrethe Boyd A1 Frank Rosenzweig A1 William C. Ratcliff YR 2018 UL http://biorxiv.org/content/early/2018/06/07/247361.abstract AB The transition from unicellular to multicellular life was one of a few major events in the history of life that created new opportunities for more complex biological systems to evolve. Predation is hypothesized as one selective pressure that may have driven the evolution of multicellularity. Here we show that de novo origins of simple multicellularity can evolve in response to predation. We subjected outcrossed populations of the unicellular green alga Chlamydomonas reinhardtii to selection by the filter-feeding predator Paramecium tetraurelia. Two of five experimental populations evolved multicellular structures not observed in unselected control populations within ~750 asexual generations. Considerable variation exists in the evolved multicellular life cycles, with both cell number and propagule size varying among isolates. Survival assays show that evolved multicellular traits provide effective protection against predation. These results support the hypothesis that selection imposed by predators may have played a role in some origins of multicellularity.