Evolution 2009: Day one

In this morning’s session on species interactions and coevolution, everyone was talking about these videos of snakes attacking snails. Turns out that snail shell chirality (the direction the shell spirals) can determine how easy it is for a snake to attack. Very, very cool. Detailed discussion by John Dennehy is here. [Edit, 14 June 2009: link to the video originally found by Matt Labrum.]

I presented today, and survived another twelve-minute talk. Immediately after I finished describing my preliminary conclusion that coevolution between species only generates evolutionary diversity if it exerts disruptive selection on one or the other interactor — the best example of which may be competitive exclusion — Jeremy Fox described a model in which competitor species converge on a single set of traits [$-a]. It’s a cool result, and one I’ll need to consider carefully.

I also learned today that

  • A bacterial endosymbiont helps fruit flies fight off parasitic worms;
  • It might not “cost” anything for some specialist herbivores to sequester the toxins produced by the plants they eat;
  • Coevolution can actually change the migration rates of interacting species; and
  • Bacteria and phage living inside horse chestnut leaves are locally adapted within individual trees, but not within individual leaves.

Was out way too late, as the timing of this post may indicate. Don’t think I’ll make the morning sessions. Not that the love-in-a-canoe coffee provided by campus catering will help. Ugh.


Fox, J., & Vasseur, D. (2008). Character Convergence under Competition for Nutritionally Essential Resources The American Naturalist, 172 (5), 667-80 DOI: 10.1086/591689