Month: August 2018

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The paper describing the genetics of the multicellular Chlamydomonas reinhardtii strain that evolved in response to selection on settling rate is published in Royal Society Open Science:

Figure 3 from Herron et al. 2018. Results of phylostratigraphy analysis of differentially expressed genes. The y-axis represents the log odds of the observed degree of over/underrepresentation relative to genome-wide frequencies. The Bonferroni-corrected p-values result from a hypergeometric test (α = 0.0025, equivalent to a false discovery rate of 1%) performed in GeneMerge v. 1.4. ‘n.s.’, not significant.

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I’m a junior author on a new paper from Erik Hanschen and colleagues, “Multicellularity drives the evolution of sexual traits.”

Figure 3 from Hanschen et al. 2018. Figure 3. Ancestral state reconstructions of six sexual characters. A, Evolution of all (green) and reduced number of (black) meiotic products germinating from a diploid zygospore. B, Evolution of isogamy (green), anisogamy (blue), and oogamy (black). C, Evolution of external (green) and internal (black) fertilization. D, Evolution of normal females (green) and extrafertile females (black). E, Evolution of normal males (green) and dwarf males (black). 

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Pennisi figure
Top left: Chlamydomonas (Andrew Syred/Science Source). Top right: Gonium (Frank Fox/ Science Photo Library). Bottom: Volvox (Wim van Egmond/Science Photo Library).

A news item by Elizabeth Pennisi in Science mentions our work experimentally evolving multicellularity in Chlamydomonas reinhardtii:

[Will Ratcliff’s snowflake] yeast results weren’t a fluke. In 2014, Ratcliff and his colleagues applied the same kind of selection for larger cells to Chlamydomonas, the single-celled alga, and again saw colonies quickly emerge. To address criticism that his artificial selection technique was too contrived, he and Herron then repeated the Chlamydomonas experiment with a more natural selective pressure: a population of paramecia that eat Chlamydomonas—and tend to pick off the smaller cells. Again a kind of multicellularity was quick to appear: Within 750 generations—about a year—two of five experimental populations had started to form and reproduce as groups, the team wrote on 12 January in a preprint on bioRxiv.