A recent Bioephemera post highlights the work of Holly Wichman, a professor at the University of Idaho who makes models of bacteriophages. When I was at the University of Idaho, Holly was still working on LINE-1 retrotransposons and I was studying pronghorn social behavior. Since then we've both converged on phage research. She has proven far more creative than I in this field.
Mendeleev's Periodic Table is a marvel of an information source. So much data is packed into this fairly simple looking chart, including symbol, atomic number and mass, electron configuration, and valence. I really didn't think it could be improved upon. That is until I found this web version. Clicking on the elements brings up the element's wiki page and all the info contained therein. A sliding bar in the upper right corner shows the temperatures of transition states. You can click on series, properties, orbitals and isotopes to find further information for each element. Sweet!
Mark Gerstein and colleagues published a very nice review of the gene in Genome Research this summer, and I missed it. I think I was on vacation in Wyoming. Anyway, I just found it now. If you missed it too, definitely check it out. The review covers how genes were conceptualized since their "discovery" by Mendel, and touches upon all the major milestones in the history of genetics. The authors then discuss issues with the current conception of the gene, and propose a new model. Here is their summary:
A proposed updated definition
There are three aspects to the definition that we will list below, before providing the succinct definition:
This can be concisely summarized as:
The gene is a union of genomic sequences encoding a coherent set of potentially overlapping functional products.
Normally I don't advertise commercial interests on this site; the Evilution Store was an exception, but I'm about to make another one... Marek Eby sent me a note pointing out his Trilobite clothing line. I love this kind of stuff... the geekier the better. I think this kind of advertising does an important service; it increases the visibility of science in general and evolution in particular in popular culture. At any rate , it's a lot better than wearing a shirt with a Nike logo. I'm sure Anne-Marie would love this one. The shirt depicting a Velociraptor wearing a beret a la Che Guevara is my favorite (see above). Oh and Christmas is coming soon. No reason. Just thought I'd mention that.
The Spandrels of San Marco and the Panglossian Paradigm: A Critique of the Adaptationist Programme. S. J. Gould, R. C. Lewontin Proceedings of the Royal Society of London. Series B, Biological Sciences, Vol. 205, No. 1161, The Evolution of Adaptation by Natural Selection (Sep. 21, 1979), pp. 581-598.
I confess I am not a huge fan of Stephen Jay Gould. Although his extensive science writing is often charming, and has helped popularize evolutionary biology across a much broader spectrum (Wonderful Life was wonderful!), I consider much of his evolutionary thought simply wrong headed and strange. I won't go into specifics here, *cough, cough, punctuated equilibrium*, but some of his work is basically window dressing. I haven't read his latest opus, The Structure of Evolutionary Theory (its size, 5.1 pounds, is quite daunting; I'm waiting for the Reader's Digest version) so I could be wrong here, but I doubt it.
Dick Lewontin, on the other hand, is a great evolutionary biologist and has made many seminal contributions to the field.
Despite my misgivings about Gould, I found the paper on the Adaptationist Programme to be spot on. First off, it has a fantastic title. Not a cutesy punning title, but a novel, eye-catching title with side references and metaphors that actually make sense.
Second, the paper addressed a real concern in evolutionary biology. Despite G.C. Williams tour-de-force, Adapatation and Natural Selection, the study of adaptation in the '70s still suffered from wishy-washy, uncritical thinking (Larry Moran might argue still does today!). The problem was Just So stories (so named after the Kipling kiddie stories about How the Leopard Got His Spots etc.) where anyone can invent reasons, however fanciful, for why certain phenotypic traits exist.
Gould and Lewontin cite experimental work by D.P. Barash as an example of this problem.
Barash mounted a stuffed male near the nests of two pairs of bluebirds while the male was out foraging. He did this at the same nests on three occasions at ten-day intervals: the first before eggs were laid, the last two afterwards. He then counted aggressive approaches of the returning male toward the model and the female. At time one, aggression was high toward the model and lower toward females, but substantial in both nests. Aggression toward the model declined steadily for times two and three and plummeted to near zero toward females. Barash reasoned that this made evolutionary sense, since males would be more sensitive to intruders before eggs were laid than afterward (when they can have some confidence that their genes are inside). Having devised this plausible story, he considered his work as completed.
The explanation misses an obvious alternative. Perhaps the males approached the models a few times, learned that they were fake, and thereafter no longer responded to them. The proper way to conduct this experiment is to expose a male to the model once... either before or after the eggs are laid. The experiment was replicated by Morton et al. (1978) who found no evidence for anti-cuckoldry behavior.
Gould and Lewontin believed that too many biologists were simply making up similar stories for every conceivable trait. Perhaps some organismal traits have no function! Take the belly button. Maybe it evolved to collect lint so that cavemen would have a source of fiber for their diets! Uhhm... not likely. The belly button is an example what Gould and Lewontin would call a spandrel. The San Marco spandrels are so beautifully decorated with mosaics that one could be convinced that they were designed expressly to display mosaics. Not so! Spandrels simply hold up the ceiling; they were painted to make them look pretty. Belly buttons serve no function; they are simply the remnant of the umbilical connection between the mother and fetus.
So how should one determine whether a certain trait is an adaptation? A good adaptive hypothesis will make predictions concerning the trait it seeks to explain. Also several criteria should be met: (1) trait variation must affect fitness or a component of fitness; (2) the hypothesis of adaptive variation must be confirmed by either manipulating the selective environment or the phenotypic trait itself; and (3) the mechanistic link between the trait and fitness must be demonstrated.
James Audubon gets all the press, but Maria Sibylla Merian could give him a run for the money in the artist/naturalist department. In 1699, she traveled from Amsterdam to Surinam, where she explored the Surinam River and its surrounding rainforest. Along the way, she sketched the local fauna and flora for her masterwork, The Metamorphosis of the Insects of Surinam, published in 1705. She is the subject of a new biography by Kim Todd, Chrysalis, Maria Sibylla Merian and the Secrets of Metamorphosis.
A nice flash gallery of selected plates is available here (the above thumbnail does her work no justice). Learn more about her at the National Museum of Women in the Arts.
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