Tag: Evolution

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With the permission of the publisher and the authors, we have made internally peer-reviewed but unformatted drafts of all 18 chapters of The Evolution of Multicellularity available for download. Please note that there may be substantive differences between these pre-publication versions and the final book chapters.

The full book is available on Amazon and direct from the publisher in hardcover and ebook formats. The paperback is due out in 12-18 months, at which point the price of the ebook will drop.

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The Evolution of Multicellularity, co-edited with Peter Conlin and Will Ratcliff, has been published by CRC Press. It’s available on Amazon, but cheaper to order direct, and for the time being you can save 20% with discount code FLA22 (I don’t know how long that will last).

The goal of this book is to provide an overview of the evolution of multicellularity: the types of multicellular groups that exist, their evolutionary relationships, the processes that led to their origins and subsequent evolution, and the conceptual frameworks in which their evolution is understood. In four main sections, the contributors review the philosophical issues and theoretical approaches to understanding the evolution of multicellularity, the evolution of aggregative multicellularity, the evolution of clonal multicellularity, and the evolution of multicellular life cycles and development. While the subject is too broad to cover in a truly comprehensive way, the contributors have done an outstanding job of synthesizing the critical information on their respective topics. We hope that this book will serve as a starting point for readers interested in the evolution of multicellularity, a reference for researchers on the subject, and a jumping-off point to stimulate future research.

The publisher has put pretty strict limits on what we can share (they want to sell books, after all), so I won’t be posting a downloadable version (I don’t, in fact, have one). However, the Foreword and Chapter 1 (together) can be downloaded for free, and some of the authors posted preprints of their chapters (which the publisher allowed). I have linked to these in the table of contents below. If I learn of others, I’ll update this post.

I’m biased, of course, but I really do think the authors have done an outstanding job with their respective chapters. I hope you think so, too!

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A new paper describing the results of a yeast evolution experiment has been published in Evolution. Jordan Gulli exposed nascent multicellular “snowflake yeast” to an environment in which solitary multicellular clusters experienced low survival. In response, snowflake yeast evolved to form cooperative groups composed of thousands of multicellular clusters.

Gulli et al. 2019 Fig. 2
Figure 2 from Gulli et al. 2019. Evolution of proteinaceous aggregates that bind many multicellular clusters. When subjected to strong settling selection, snowflake yeast evolved to form cooperative aggregates composed of hundreds of clusters (A). A composite image (B) reveals the aggregates are composed of both protein (C, green, Qubit fluorescent protein stain) and DNA (D, red, propidium iodide). Cells embedded within the aggregate are shown in blue (E, Cell Tracker Blue). Scale bars are 500 μm.

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A new paper describing the results of a microbial evolution experiment has been published in Scientific Reports. Predation by the filter-feeding predator Paramecium tetraurelia drove the evolution of simple multicellular structures in the green alga Chlamydomonas reinhardtii:

Herron et al. 2019 Fig. 2
Figure 2 from Herron et al. 2019. Depiction of C. 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. Representative microscopic images of each life cycle category are at the bottom (Depicted strain in boldface).

From the abstract:

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.

Herron MD, Borin JM, Boswell JC, Walker J, Knox CA, Boyd M, Rosenzweig F, Ratcliff WC. 2019 De novo origins of multicellularity in response to predation. Sci. Rep. 9, 2328. (doi: 10.1038/s41598-019-39558-8)