Since I was sent this photo from the evo-devo conference by Kevin Emerson, I couldn’t resist: this is the aftermath of two scientists duking it out in an intellectual arena.
Obviously, they had to wear different colored shirts so we could tell them apart in the maelstrom of the fray.
[Since I had to fly away early this morning and missed all these talks, I had to rely on regular commenter DanioPhD to fill in the gaps … so here’s her summary:]
This morning’s final series of talks each focused on a different phylum, but the unifying theme was one of bridging the processes of microevolution and macroevolution. The first talk after breakfast (and a long night of Scotch-drinkin’ and story-swappin’ prior to that) was Bernie Degnan of the University of Queensland. He summarized his work on Amphimedon queenslandica, a sponge species developed as a model of a representative primitive metazoan. Sponges diverged from the metazoan lineage ca. 700 MYA and possess the most minimalist metazoan body plan–no nervous system, muscles, nor any discernible tissues in the adult body architecture. Their embryos, however, feature robust anterioposterior patterning, distinct cell types organized into tissues, and cell morphogenesis typical of more complex metazoans. These embryonic characteristics are achieved by a regulatory network of genes, which, while inactive in the adult sponge, strongly support the presence of similar molecules in the ancestral metazoan genome. A few million years after the divergence of porifera, metazoans were able to co-opt these molecular toolkits to build the diverse, molecularly and morphologically distinct tissues common to all bilaterians. PZ has previously written up one such sponge tale here describing the molecular precursors to a nervous system in the sponge genome. Precursors to pretty much every other developmental ‘big gun’, e.g, Hox genes, Pax genes, Wnts, Hedgehog, etc. are also present as a basic prototype, in the Amphimedon genome.
I’m going to get off a quick summary of this afternoon’s talks, then I have to run down to the poster session to find out what the grad students have been doing. Are we having fun yet? I’m going to collapse in bed tonight, and then unfortunately I have to catch an early flight back home, so I’m going to miss a lot of cool stuff tomorrow.
My brain is most wonderfully agitated, which is the good thing about going to these meetings. Scientists are perverse information junkies who love to get jarred by new ideas and strong arguments, and meetings like this are intense and challenging. I’ve only got a little time here before the next session, so let me rip through a short summary of my morning.
So here I am at the IGERT Symposium on Evolution, Development, and Genomics, having a grand time, even if I did get called out in the very first talk. There were two keynote talks delivered this evening, both of which I was anticipating very much, and which represented the really good side of science: two differing points of view wrestling with each other for consensus and for testable, discriminating differences. They also had dueling t-shirts.
What an honor: Jeff Medkeff, an astronomer and discoverer of asteroids, has been generous to name a recently discovered set of distant rocks after Michael Stackpole, Rebecca Watson, Phil Plait, and me. That’s right, there is now a few billion tons of rock and metal spinning overhead with my name on it, asteroid 153298 Paulmyers. You can find a picture of its orbit and location, just in case you want to visit.
Now I don’t know much about astronomy — I know this rock doesn’t have any squid on it, unfortunately, and that it’s small, cold, and remote (hey, just like where I am now! Only more so!) — but Phil Plait describes the details of his asteroid.
To give you an idea of the asteroid’s size, it has more than 200 times the volume of Hoover Dam. Assuming that it’s made of rock, it has a mass of about 2 quadrillion grams, or about 2 billion tons. If it’s metal it’ll be about twice that massive.
When I mentioned this to Skatje, the first thing she asked was whether mine was bigger than Phil’s. Phil admits that it probably is twice the size, although it’s an estimate from relative brightness, so it could be that they’re of similar size, but mine is brighter, or Phil’s is dimmer … it’s all good. The rivalry continues!
Now I have to wonder…do I have mineral rights? Can I at least retire to 153298 Paulmyers? When’s the next space bus to the asteroid belt? How about some photos of my rock (near as I can tell, any photo is going to be just of a tiny point of reflected light)?
The Harvard multimedia team that put together that pretty video of the Inner Life of the Cell has a whole collection of videos online (including Inner Life with a good narration.) Go watch the one titled F1-F0 ATPase; it’s a beautiful example of a highly efficient molecular motor, and it’s the kind of thing the creationists go ga-ga over. It’s complex, and it does the same rotary motion that the bacterial flagellum does; it has a little turbine in the membrane, a stream of protons drives rotation of an axle, and the movement of that axle drives conformation changes in the surrounding protein that promote the synthesis of ATP. It’s a molecular machine all right. Makes a fellow wonder if possibly it’s “irreducible”, doesn’t it?
Well, it’s not. It can be broken down further and it still retain that rotary motion.
Fossils are cool, but some of us are interested in processes and structures that don’t fossilize well. For instance, if you want to know more about the evolution of mammalian reproduction, you’d best not pin your hopes on the discovery of a series of fossilized placentas, or fossilized mammary glands … and although a few fossilized invertebrate embryos have been discovered, their preservation relied on conditions not found inside the rotting gut cavity of dead pregnant mammals.
You’d think this would mean we’re right out of luck, but as it turns out, we have a place to turn to, a different kind of fossil. These are fossil genes, relics of our ancient past, and they are found by digging in the debris of our genomes. By comparing the sequences of genes of known function in different lineages, we can get a measure of divergence times … and in the case of some genes which have discrete functions, we can even plot the times of origin or loss of those particular functions in the organism’s history.
Here’s one example. We don’t have any fossilized placentas, but we know that there was an important transition in the mammalian lineage: we had to have shifted from producing eggs in which yolk was the primary source of embryonic nutrition to a state where the embryo acquired its nutrition from a direct interface with maternal circulation, the placenta. We modern mammals don’t need yolk at all … but could there be vestiges of yolk proteins still left buried in our genome? The answer, which you already know since I’m writing this, is yes.
You know how people can be going along, minding their own business, and then they see some cute big-eyed puppy and they go “Awwwww,” and their hearts melt, and then it’s all a big sloppy mushfest? I felt that way the other day, as I was meandering down some obscure byways of the developmental biology literature, and discovered the dicyemid mesozoa … an obscure phylum which I vaguely recall hearing about before, but had never seriously examined. After reading a few papers, I have to say that these creatures are much more lovable then mere puppy dogs. Look at this and say “Awwwww!”
O dicyemid mesozoan, how do I love thee? Let me count the ways.
My last column in Seed is now online for you cheapskates (OK, you’re forgiven already) who don’t subscribe. It’s called “Eyeing the Evolutionary Past,” and discusses a familiar topic around these parts — the evolution of eyes.
