Back when I was a cocky grad student, I wrote a paper that was, in some ways, critical of the work of one of the biggest names in my field. David Kirk, who passed away last year, was among the most important figures in establishing Volvox as a model system for development, genetics, and evolution, among other things. He had published a paper that I thought was unnecessarily progressivist, and I said so in terms that, in retrospect, could have been more diplomatic. In response, Dr. Kirk, whom I had never met, sent me a very thoughtful email thanking me for pointing out some of the problems and politely disagreeing on some other points. Its tone was kind and respectful when annoyed and argumentative would have probably been justified.

In that email, he offered a bet, the stakes of which were to be a beer, that one of the things I had suggested would turn out to be wrong. The issue had to do with inversion, a process that the (mostly) spheroidal algae in the family Volvocaceae undergo during development. I have written about inversion many times on Fierce Roller; in a nutshell, these algae start their lives inside-out, with their flagella on the inside, and invert to get the flagella on the outside, where they can be used for swimming. Their relatives in the genus Gonium also undergo a process of partial inversion, changing from cup-shaped (with the flagella on the concave side) to flat or slightly cup-shaped in the other direction. Dr. Kirk had interpreted Gonium‘s partial inversion as a probable intermediate step that led to the complete inversion characteristic of the Volvocaceae. My reconstructions suggested that incomplete inversion in Gonium had evolved separately from complete inversion in the Volvocaceae, and Dr. Kirk bet me that this would turn out to be wrong.

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