Carnivalia, and an open thread

It’s Friday! I have no classes today, so this is the day where I desperately struggle to catch up with the backlog; it also happens to be the day we’re hosting a party at our house (you’re invited: 5:30, my place, across the street from the university; everyone who is anyone will be there). If you can’t make it, I expect you to make small talk and chat sociably in this open thread.

Here are a few ice-breakers to help you get started.

The Tangled Bank

The next edition of the Tangled Bank will be at the Behavioral Ecology blog — send those links in to me or host@tangledbank.net before Wednesday, 12 September.

Jaws of the moray

Blogging on Peer-Reviewed Research

The vertebrate jaw is a product of evolution — we have a serially repeated array of pharyngeal structures as embryos (and fish retain them in all their bony glory as gill arches), and the anterior most arch is modified during our development to form the jaws. The fact that they’re serially repeated raises an interesting possibility: what if, instead of just the one developing into a jaw, others were transformed as well? You could have a whole series of jaws!

One animal has done exactly that. The moray eel has modified one of the more posterior pharyngeal arches into a second pair of jaws, with a set of muscles that can slide it forward to bite prey already held in the mouth.

[Read more…]

Evolution of the cichlid mandible

i-ccbc028bf567ec6e49f3b515a2c4c149-old_pharyngula.gif

When we look at the face of another person, we can recognize specific features that have familial resemblances. In my family, for instance, I can recognize a “Myers nose” that my grandmother and my father and some of my siblings and kids have, and it’s different than my wife’s or my mother’s nose. These are subtle differences in shape—a bit of a curve, a knob, a seam—and their inheritance suggests that these differences are specified somehow in the DNA. If you think about it, though…how can whether the profile of a nose is straight or curved be encoded in a linear stretch of nucleotides? The complicated answer is that it isn’t—morphology is a consequence of epigenetic interactions during development—but we know that the alleles present in the genome do contribute in some significant way to three-dimensional form. How?

We don’t know all the details. This is one of those huge research problems that has gaping holes, full of promise and interest, where we don’t understand exactly how all the pieces fit together. However, here’s an important point that is relevant to other, larger issues in evolution: even where we lack full information about mechanisms, we can roughly perceive the shape of the answer, and that helps us rule out many alternative explanations and guides us in the general direction of a more complete understanding.

People’s noses are a difficult subject for research; we don’t get to define human crosses, people tend to be a little snippy about telling them who to breed with and taking their genes apart, and humans are awfully slow to breed. Fish are better experimental animals, much more pliable and faster and more prolific in their breeding. Some fish, such as the African cichlids, also have highly diverse populations and species with easily recognized and often quite dramatic morphological differences—and we can explore how those differences are generated by genetic and molecular differences in development. In particular, we can start to figure out how fish jaws are shaped by developmental processes.

[Read more…]

Two horrible new diseases

Scott Lanyon, director of the Bell Museum, has an article on two disease we should worry about, VHSv and EAS.

Personally, I think VHSv is the worst. It’s a virus that causes hemorrhagic septicemia in fish; just from the name you know it’s bad, involving blood and sepsis. My most horrible experience raising zebrafish was the time hemorrhagic septicemia swept through my colony and I had to euthanize every animal and bleach every last bit of plumbing to eradicate it. This disease has been detected in waters of Wisconsin, and it’s definitely not good.

EAS may not be as dramatically gory and lethal in its effects, but it strikes humans directly. It’s Evolution Avoidance Syndrome, and it causes the brains of scientists and journalists to seize up when circumstances are appropriate to discuss evolution in public. Apparently, we want local fish populations to develop, acquire, improve or have arise resistance to the hemorrhagic septicemia virus; we can’t possibly suggest that evolution might be at work.

Dawkins reviews God is Not Great

And what a sweet review it is. There are points on which I disagree with Hitchens (as there are with Dawkins, too, of course), but I agree that the book is an excellent contribution to the ongoing evolution of secular thought.

I wonder if one of the factors that is making everyone consider this movement the “New Atheism” is a confusion of cause and effect. The cause, the advancement of outspoken atheism, is the same old idea; the effect is different, because we don’t have just one Ingersoll who could be marginalized and humored because he was mostly alone, we have a growing core of literate and uncompromising atheists who can reinforce each others’ message, leading to greater and greater gains. Hitchens and Dawkins, despite differences in politics and perspectives, can find common cause in one thing, at least, and will gladly work together to promote it. And everywhere new groups supporting secularism are springing up and encouraging discussion and criticism of religion.

If I were a follower of one of the Abrahamic religions, I’d be worried. The opposition is growing bolder, and their religious belief relies on acceptance of authority — and that is being challenged and weakened.