Evolutionary history of yucca moths
I've written a few posts about ancestral-state reconstruction, where we use molecular or other information from living species to infer the traits of their shared ancestors. But I really like this post in which PhD student Jeremy Yoder describes his own work.
There's a nice diagram showing the general approach, then he looks at yucca moths and their relatives to figure out what their ancestors did. Yucca moths, like fig wasps, lay their eggs in flowers. Their larvae eat seeds, but the moths pollinate the flowers, so it's not too bad a deal overall. Their ancestors, he concludes, fed inside developing flowers, but without pollinating them. Maybe the world is getting a little more cooperative, after all.