Quote of the week

Mike the Mad Biologist wins a gold star for this quote that I’ll be stealing:

The other thing we evolutionary biologists don’t do enough of, and this stems from the previous point, is make an emotional and moral case for the study of evolution. Last night, I concluded my talk with a quote from Dover, PA creationist school board member William Cunningham, who declared, “Two thousand years ago someone died on a cross. Can’t someone take a stand for him?”

My response was, “In the last two minutes, someone died from a bacterial infection. We take a stand for him.”

Now that is good framing.

Eppur si muove!

Blogging on Peer-Reviewed Research

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.

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Reproductive history writ in the genome

Blogging on Peer-Reviewed Research

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.

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Dicyemid mesozoa

Blogging on Peer-Reviewed Research

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!”

i-67abe67694eea42539187c64ab322994-dicyemid.jpg
Light micrograph of Dicyemid japonicaum rhombogen. AX, axial cell; C, calotte; IN, infusorigen; P, peripheral cell.

O dicyemid mesozoan, how do I love thee? Let me count the ways.

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Evolution 2008 is for teachers

Teachers, come to Minneapolis this summer! Not for the Republican convention, but for the other great big important meeting that will be taking place: Evolution 2008.

Teachers in particular get a really good deal: a special workshop is planned, specifically on the teaching of evolutionary biology in the schools. We’ve got some good speakers (and me) lined up, and the registration cost of a mere $20 not only gets you into the workshop, but into the regular meetings as well. Here are the details:

Evolution 101 Workshop for K-12 Educators
Friday, June 20, 2008
Bell Museum of Natural History
University of Minnesota
.625 CEUs

One $20 registration also gives K-12 teachers access to sessions and symposia by the sponsoring scientific organizations, as well as social events and keynote speakers for the full conference, June 20-24.

The EVOLUTION 101 workshop provides K-12 educators with information to effectively teach evolutionary biology in public and private school science classrooms. The workshop provides teachers the opportunity to interact with professional scientists who are eager to encourage evolutionary pedagogy. With one registration, K-12 teachers will also have access to presentations by the professional organizations, as well as keynote speakers for the full conference, June 20-24.

Registration: $20 non-refundable

A certificate of completion and .625 Continuing Education Units will be awarded for attendance at this workshop.

For more information about this workshop and to register on-line, please visit:
http://www.cce.umn.edu/conferences/evolution/evolution_101.html

The workshop is sponsored by the Society for the Study of Evolution (SSE), Minnesota Citizens for Science Education (MnCSE), and the Bell Museum of Natural History, with the generous financial support of the ADC Foundation.

The University of Minnesota is an equal opportunity educator and employer.
© 2008 Regents of the University of Minnesota. All rights reserved

An exercise for the readers

I and a diverse group of people got a question in email, one that we are supposed to answer in a single sentence. The question is,

What is evolution?

You know, Ernst Mayr wrote a whole book to answer that question on a simple level, and I’m supposed to have the hubris to answer that in one sentence? OK, knowing full well that it is grossly inadequate, here’s my short answer:

Evolution is a well-confirmed process of biological change that produces diversity and coherent functionality by a variety of natural mechanisms.

Go ahead, you people try to answer it in one sentence in the comments. It’s harder than it looks, especially since I feel the itch to expand each word into a lecture.

By the way, when I say this question was sent to a diverse group of people, I mean a diverse group of people. One of them was the author of this book, and another was from this site, and you can imagine what their answers were. (Sorry, they were sent out with some expectation of confidentiality, so I can’t tell you them. Maybe they’ll notice all the traffic to their websites and share it with us.)

The choanoflagellate genome and metazoan evolution

Blogging on Peer-Reviewed Research

What are the key innovations that led to the evolution of multicellularity, and what were their precursors in the single-celled microbial life that existed before the metazoa? We can hypothesize at least two distinct kinds of features that had to have preceded true multicellularity.

  • The obvious feature is that cells must stick together; specific adhesion molecules must be present that link cells together, that aren’t generically sticky and bind the organism to everything. So we need molecules that link cell to cell. Another feature of multicellular animals is that they secrete extracellular matrix, a feltwork of molecules outside the cells to which they can also adhere.

  • A feature that distinguishes true multicellular animals from colonial organisms is division of labor — cells within the organism specialize and follow different functional roles. This requires cell signaling, in which information beyond simple stickiness is communicated to cells, and signal transduction mechanisms which translate the signals into different patterns of gene activity.

These are features that evolved over 600 million years ago, and we need to use a comparative approach to figure out how they arose. One strategy is to pursue breadth, cast the net wide, and examine divergent forms, for instance by
comparing multicellular plants and animals. This approach leads to an understanding of universal properties, of how general programs of multicellular development work. Another is to go deep and examine closer relatives to find the step by step details of our specific lineage, and that’s exactly what is being done in a new analysis of the choanoflagellate genome.

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The genome is not a computer program

The author of All-Too-Common Dissent has found a bizarre creationist on the web; this fellow, Randy Stimpson, isn’t at all unusual, but he does represent well some common characteristics of creationists in general: arrogance, ignorance, and projection. He writes software, so he thinks we have to interpret the genome as a big program; he knows nothing about biology; and he thinks his expertise in an unrelated field means he knows better than biologists. And he freely admits it!

I am not a geneticist or a molecular biologist. In fact, I only know slightly more about DNA than the average college educated person. However, as a software developer I have a vague idea of how many bytes of code is needed to make complex software programs. And to think that something as complicated as a human being is encoded in only 3 billion base pairs of DNA is astounding.

Wow. I know nothing about engine repair, but if I strolled down to the local garage and tried to tell the mechanics that a car was just like a zebrafish, and you need to throw a few brine shrimp in the gas tank now and then, I don’t think I would be well-received. Creationists, however, feel no compunction about expressing comparable inanities.

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