Live from Ottawa
I'm at Evolution 2012, a joint meeting of several evolutionary biology societies in Ottawa.
Caroline Turner discussed feedbacks between ecology and evolution after one of Rich Lenski's long-term E. coli populations acquired a citrate-using mutant. The transporter that takes up the citrate actually swaps out a succinate, which is another potential food source. During the time when citrate(+) and citrate(-) genotypes coexisted, the citrate(-) part of the population evolved an improved ability to use succinate, with some decrease in its ability to grow on glucose.
Have I mentioned that evolutionary tradeoffs are a major theme of my book, Darwinian Agriculture? Princeton University Press is selling it here, along with Angela Douglas's book on symbiosis, among others.
Adam Waite discussed experiments with Wenying Shou on evolution of cooperation. Two yeast genotypes "cooperate" by each making something the other needs but can't make itself. But what keeps "cheaters", which consume those "common goods" without contributing, from taking over? Sure, the population would then go extinct, but evolution doesn't plan ahead.
When they divided a 1:1:1 mixture of the two cooperators and the cheater into 3 mL tubes, some populations grew fast and eliminated the cheaters, while others became all cheaters and then crashed. This apparently depended on whether a key beneficial adaptation (a mutated nutrient transporter) appeared first, within a given tube, in a cooperator or a cheater. I wonder whether, with much larger populations the cheater would usually get the adaptation soon enough to avoid being eliminated. But this does seem like a plausible explanation for the evolution of cooperation in the face of cheating. I was also liked their methods: 3 different fluorescent labels, so they could analyze composition of mixtures by flow cytometry.
Next I'm going to a series of talks on the evolution of aging.