Month: July 2019

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Herron et al. 2019 Fig. 2
Figure 2 from Herron et al. 2019. Depiction of Chlamydomonas reinhardtii life cycles following evolution with (B2, B5) or without (K1) predators for 50 weeks. Categories (A–D) show a variety of life cycle characteristics, from unicellular to various multicellular forms. Briefly, A shows the ancestral, wild-type life cycle; in B this is modified with cells embedded in an extracellular matrix; C is similar to B but forms much larger multicellular structures; while D shows a fully multicellular life cycle in which multicellular clusters release multicellular propagules. Evolved strains were qualitatively categorized based on growth during 72-hour time-lapse videos. Strains within each life cycle category are listed below illustrations. Representative microscopic images of each life cycle category are at the bottom (Depicted strain in boldface).

The Project Outcomes Report for our recently ended NSF grant (known variously as DEB-1723293, DEB-1457701, and DEB-1456652) is now available on grants.gov:

Life comes in two forms: single-celled (organisms made up of only one cell) and multi-celled (organisms made up of many cells, alike or different). Multicellular life has evolved from unicellular ancestors many times across the tree of life, and the resulting radiations have transformed nearly every ecosystem on Earth. Ancestors of animals, plants, fungi, several groups of seaweeds, and filamentous bacteria underwent the transition from single- to multi-celled life in the deep past. While each of these origins is a replicate experiment with the potential to inform our understanding of how and why multicellular life evolved, the window through which we see these ancient events is blurry. Extinctions, subsequent evolution, and a spotty fossil record obscure our view. Experimental evolution enables us to time-travel, making it possible to clearly observe the evolution of multicellularity as it occurs in the lab. This project integrated experimental, bioinformatic, theoretical, and comparative approaches to understand how multicellularity and related traits have evolved, and how they can evolve.

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