Volvox meeting posters

I thought I had already done this, but if so I can’t find it. Here are the full-resolution versions of all four Volvox meeting posters:

  • First International Volvox Meeting (Volvox 2011, Tucson, Arizona) pdf jpg
  • Second International Volvox Meeting (Volvox 2013, Fredericton, New Brunswick) pdf jpg
  • Third International Volvox Meeting (Volvox 2015, Cambridge, U.K.) pdf jpg
  • Fourth International Volvox Meeting (Volvox 2017, St. Louis, Missouri) pdf jpg (there wasn’t really a poster for this one; this is the cover of the abstract booklet)

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The Two Jakes

The organizers of the Volvox 2017 meeting put together a Volvox trivia quiz, and one of the questions had to do with a 1990 movie in which Volvox had had a cameo appearance. I was stumped. I knew Europa Report was much more recent. I probably didn’t know what Volvox was in 1990, and I don’t think I had seen the movie in question, which turned out to be The Two Jakesa sequel to 1974’s Chinatown

The Two Jakes

Because that’s how dedicated I am, I rented and watched both videos and screen captured the clip in question. Sorry there’s no sound. [somewhat important spoiler below the fold]

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Exxon still loves Volvox

I hope Exxon’s scientists know more more algal taxonomy than their ad team. We’ve seen before that they don’t know the difference between Chlorophyte green algae and cyanobacteria (Exxon loves Volvox). Some of the things they’ve lumped together in that video are more distantly related than humans are to mushrooms.

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Mechanics of Volvox inversion

Variation is everywhere in biology. Structural variation is present at molecular, cellular, organismal, and population levels, and functional variation occurs in processes from metabolism to development to behavior. In spite of this, we often describe biology in typological terms, and this is often a source of confusion.

Some variation is crucial; for example, evolution is dependent on genetic variation, and behavioral variation within ant and bee colonies ensures that all the necessary jobs get done. Much variation, though, is simply biological noise, an unavoidable consequence of the mostly analogue nature of living systems. In extreme cases, variation of this sort can complicate and even derail development, but in general development is remarkably robust. A variety of regulatory mechanisms prevent small amounts of variation early in development from being amplified into large variations in adults.

Pierre Haas and colleagues have posted a preprint to arXiv describing variation in the developmental process of inversion in Volvox globator. Facultatively sexual organisms such as Volvox are great for studying non-genetic sources of variation, because it’s pretty simple to produce millions of genetically identical individuals. When they are raised in identical conditions, variation due to environmental differences is minimized, and most of the observed variation is stochastic.

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Another step toward understanding sex determination in Volvox

Volvox and its relatives are a great model system for understanding the evolution of multicellularity. Their simplicity (relative to most other multicellular groups) and the variety of ‘intermediate’ species (‘intermediate’ in terms of size and complexity) make them especially suitable for comparative studies of their morphology, development, genetics, genomics, and so on. David Kirk’s book on the topic thoroughly reviews the work done up through the late ’90s, and advances since then have only increased the pace of discovery.

But in the last ten years or so, I would argue that the volvocine algae have emerged as a leading model system for an entirely different set of questions related to the evolution of the sexes. Males and females are defined by the gametes they produce, and the sexes came into existence when their gametes diverged into two different types. The existence of different male and female gametes (sperm and eggs, in most cases) is called anisogamy, and the ancestral condition of similar gametes is isogamy.

In 2006, Hisayoshi Nozaki and colleagues reported that volvocine males evolved from the minus (isogamous) mating type. To the best of my knowledge, this is the only group for which we know this. Since then, more clues have been forthcoming, and these were competently reviewed last year by Takashi Hamaji and colleagues. A new paper in PLoS ONE, by Kayoko Yamamoto and colleagues, adds another piece to the puzzle.

Figure S2 from Yamamoto et al. 2017. Light microscopic images of Volvox africanus (homothallic, monoecious with males type) and V. reticuliferus (heterothallic, dioecious type). Scale bars = 50 μm. sp: sperm packet, e: egg. A-C. V. africanus strain 2013-0703-VO4. A. Asexual spheroid. B. Monoecious spheroid. C. Male spheroid. D, E. V. reticuliferus. D. Male spheroid in male strain VO123-F1-7. E. Female spheroid in female strain VO123-F1-6.

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A confused mess, part 1

I follow Uncommon Descent to keep up with what the cdesign proponentsists are up to, even though I’ve been banned from commentingUncommon Descent pushes out about three times as many articles as Evolution News & Views, and it’s clear that less than a third as much thought goes into each one. Worse, the articles’ authorship is rarely identified, robbing me of my second favorite sport after fly fishing, pointing out creationists’ self-contradictions. For both of these reasons, I don’t comment on their posts nearly as often. But if you read this blog at all, you must know that I can’t pass on a video that 1) claims to provide evidence against evolution and 2) has Volvox in it.

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Another take on volvocine individuality

Dinah Davison & Erik Hanschen

Dinah Davison and Erik Hanschen.

A couple of weeks ago, I indulged in a little shameless self-promotion, writing about my new chapter on volvocine individuality in Biological Individuality, Integrating Scientific, Philosophical, and Historical Perspectives. Now two graduate students in the Michod lab at the University of Arizona, Erik Hanschen and Dinah Davison, have published their own take on volvocine individuality in Philosophy, Theory, and Practice in Biology (“Evolution of individuality: a case study in the volvocine green algae“). The article is open-access, and Hanschen and Davison are listed as equal contributors.

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