Doesn’t everyone just love cephalopods? I find them to be a fascinating example of a body plan radically different from our own, the closest thing to a truly alien large metazoan on our planet. I try to keep my eyes open for new papers on cephalopod development, but unfortunately, they are rather difficult to study and data is sadly thin and tantalizing.
I just ran across a pair of papers by Jantzen and Havenhand (2003a, b) on squid mating. That’s close enough to development for me!
It’s just a photo set of pictures of quail, but I noticed that my right forefinger reflexively twitched at the photo of the Republican lawyer in the middle of them. There may be a neurological explanation for Cheney’s shotgun error, after all.
In yet another example of evolution in action, investigators have documented morphological changes in the cane toads (Bufo marinus) that infest parts of Australia. They’re an invasive species that was introduced in a misbegotten attempt to control beetles that were damaging the sugar cane crop; as it turns out, they are aggressive predators that eat lots of other native fauna, and they secrete toxins that kill animals that try to eat them.
Another feature that contributes to their unwanted success is their rapid dispersal. Individuals can move up to 1.8km per night, occupying new territory at a distressing pace. In the 70 years since they were introduced, they’ve taken over a million square kilometers of Australia. Since dispersal into virgin territories is a significant advantage for the toads, it was predicted that there would be selection for faster migration rates in the population. The authors have several lines of evidence to show that this is the case.
Wayne takes care of a downed tree, and we all learn something.
Well, I was going to put together more about this beautiful new basal tyrannosauroid from the Jurassic of China, Guanlong wucaii, but Carl Zimmer beat me to it. I’ll just show you that lovely crested skull, and below the fold, a picture of the fossil in situ, and let Carl do the hard work of explaining it all.
Here’s some very cool news: scientists have directly observed the evolution of a complex, polygenic, polyphenic trait by genetic assimilation and accommodation in the laboratory. This is important, because it is simultaneously yet another demonstration of the fact of evolution, and an exploration of mechanisms of evolution—showing that evolution is more sophisticated than changes in the coding sequences of individual genes spreading through a population, but is also a consequence of the accumulation of masked variation, synergistic interactions between different alleles and the environment, and perhaps most importantly, changes in gene regulation.
Unfortunately, it’s also an example of some extremely rarefied terminology that is very precisely used in genetic and developmental labs everywhere, but probably makes most people’s eyes glaze over and wonder what the fuss is all about. I’ll try to give a simple introduction to those peculiar words, and explain why the evolution of a polyphenic pigment pattern in a caterpillar is a fascinating and significant result.
Carl Zimmer has the lowdown on leeches. The article is right, and they really are beautiful animals—I had a tank full of them last semester (gone now, in a flurry of bloody student labs), and watching them undulate through the water was mesmerizing. They were almost as much fun to watch as my fish.
