Against specialist herbivores, plants give up

Plants put up with a lot – everyone wants to eat them! And, basically, there are two ways a plant might respond to being eaten. They can put energy into regrowing bits that get eaten, or they can put energy into making a lot of some nasty chemical, like the milky sap in milkweed. The trouble with the first option is obvious – it doesn’t do anything to stop the damage. But the trouble with the second is that, whenever plants evolve a new defensive strategy, herbivores evolve a way around it. Often, these herbivores do very well, because they can eat something no one else can – and they become specialists on their new favorite food.

Photo by Melete.

Evolutionary ecologists have been thinking about this plant-herbivore arms race ever since Darwin. Back in 1964, Paul Erhlich and Peter Raven proposed that plants and insects might go through alternating cycles of diversification [$-a] driven by the evolution of new plant defenses and insect counterdefenses. Now, in a new paper in last week’s PNAS, Anurag A. Agrawal (who is at the top of everyone’s reference list) and Mark Fishbein show that sometimes, plants just throw in the towel [$-a].

Agrawal and Fishbein examine the evolutionary history of milkweed, which has a number of interesting anti-herbivore defenses besides the eponymous sap – and a number of specialized herbivores, like the red milkweed beetle pictured here. Their analysis looks for long-term evolutionary trends in the degree to which milkweeds put their energy into defenses, and the degree to which they put energy into regrowth. Over evolutionary time, it seems that milkweeds have reduced their defenses, and increased their regrowth efforts.


A. A. Agrawal, M. Fishbein (2008). Phylogenetic escalation and decline of plant defense strategies PNAS, 105 (29), 10057-10060 DOI: 10.1073/pnas.0802368105

P.R. Ehrlich, P.H. Raven (1964). Butterflies and plants: A study in coevolution Evolution, 18 (4), 586-608

Science as storytelling

Photo from the Radiolab blog.

This week’s podcast from Radiolab is co-host Robert Krulwich’s commencement address to the class of 2008 at the California Institute of Technology. It’s a rousing call for scientists to put in the effort to talk about science to non-scientists, and how to use stories to do it. Because, says Krulwich, science is valuable:

But somewhere in that nightmare of work [leading up to graduation] you may have noticed that your teachers were giving you more than tension headaches. They were giving you values. A deep respect for curiosity. For doubt, always doubt. For open-mindedness. For going wherever the data leads, no matter how uncomfortable.

But that doesn’t do it justice. Go listen to the whole thing. Now.

Gunman shoots eight, kills two at Unitarian church

Yesterday, Jim D. Adkisson allegedly walked into a performance of a children’s musical at the Tennessee Valley Unitarian Universalist Church in Knoxville, Tennessee and shot eight people, two of whom are now dead. Why?

According to a search warrant for Mr. Adkisson’s house filed by the police, during interrogation Mr. Adkisson admitted to the shooting and said “he had targeted the church because of its liberal leanings and his belief that all liberals should be killed because they were ruining the country.”

Local news site says that police found books by Bill O’Reilly, Michael Savage, and Sean Hannity at Adkisson’s house. Of course, those authors right-wing nutjobs didn’t tell Adkisson to shoot Unitarians (at least, not having read their books or absorbed much of their radio and TV shows, I assume they didn’t) – they’ve only made their living comparing the political opposition to terrorists, despots, and the insane. They can’t be responsible for some crazy guy in Tennessee taking it all literally.

My self-righteous fulmination aside, I believe that the people of Tennessee Valley Unitarian Universalist Church would appreciate your thoughts and prayers.

I have no idea what they’re talking about

Today’s New York Times Books section has a hand-wringing piece about the effect of Internet use on reading habits. I think the main point is that reading online shortens and fragments your attention span, but I never did finish the piece because I got distracted reading a New Yorker article on medical marijuana and a Times Magazine piece about Afghanistan while I set up an analysis on the UI supercomputing cluster and checked Facebook. And blogged about it.

(Meanwhile, I’m almost finished with the third volume of Neal Stephenson’s excellent, and lengthy, Baroque cycle, printed on good old dead trees.)

Chinese nationalism reborn

Photo by dave watts.

This week in the New Yorker there’s a great piece about resurgent feelings of nationalism in the post-Tienanmen generation. It delves beneath the recent news of anti-Western protests reacting against criticism of China’s treatment of Tibet to trace their philosophical and emotional roots. For instance, it turns out that the new Chinese nationalism has connections to American conservatism. There’s also a worrying sense that the new Chinese generation isn’t so worried about democracy, so long as they prosper:

“Chinese people have begun to think, One part is the good life, another part is democracy,” Liu went on. “If democracy can really give you the good life, that’s good. But, without democracy, if we can still have the good life why should we choose democracy?”

I guess “wiki” sounded weird once, too

Google has officially opened Knol, its answer to Wikipedia, for contributions from the general public. The principle innovation of Knol is that contributors will be encouraged to use their real identities, and primarily contribute on subjects within their own expertise. There are also apparently tools explicitly designed for collaboration.

Knol is still very much a work in progress: there are knols (= “units of knowledge,” natch) on “Leadership 101” and ganglion cysts and how to write a knol; but, as of right now, no hits on a search for “evolution,” “bicycle,” “Mennonite,” or even “plant.” Whereas Wikipedia certainly has extensive entries for each, probably including exhaustive lists of references to the terms in the films of Martin Scorsese.

For more, see the Official Google Blog and coverage by Wired.

“Evolution never takes a vacation”

This week’s column from Olivia Judson gives some examples of recent, rapid evolutionary change. She cites the evolutionary change seen in the beak size of Darwin’s finches [$-a], the flowering time of Californian field mustard [$-a], and the head shape and diet of Croatian wall lizards [$-a], but misses one of my favorite recent cases: the weed Crespis sancta.

This little plant recently moved into urban Montpelier, France, wherever its seeds land on cracks in the sidewalk or end up in patches of landscaping. And that urban landscape poses a problem for C. sancta – its seeds normally disperse like a dandelion’s, by floating on little feathery vanes. But if a plant is surrounded by pavement, most seeds that disperse this way will end up on pavement, unable to take root. So, as a recent study [$-a] shows, natural selection has favored a mutant C. sancta that doesn’t have vanes on its seeds. Vane-less seeds land right next to their parent plant, where there’s sure to be soil.

Of course, there are lots of instances of evolution in action that Judson hasn’t cataloged – because, as she rightly says, it’s going on everywhere, all the time: “Evolution never takes a vacation.”


P. R. Grant (2006). Evolution of Character Displacement in Darwin’s Finches Science, 313 (5784), 224-226 DOI: 10.1126/science.1128374

S. J. Franks, S. Sim, A. E. Weis (2007). Rapid evolution of flowering time by an annual plant in response to a climate fluctuation PNAS, 104 (4), 1278-1282 DOI: 10.1073/pnas.0608379104

A. Herrel, K. Huyghe, B. Vanhooydonck, T. Backeljau, K. Breugelmans, I. Grbac, R. Van Damme, D. J. Irschick (2008). Rapid large-scale evolutionary divergence in morphology and performance associated with exploitation of a different dietary resource PNAS, 105 (12), 4792-4795 DOI: 10.1073/pnas.0711998105

P.-O. Cheptou, O. Carrue, S. Rouifed, A. Cantarel (2008). Rapid evolution of seed dispersal in an urban environment in the weed Crepis sancta PNAS, 105 (10), 3796-3799 DOI: 10.1073/pnas.0708446105

Berea College: Wait, there’s more!

And but so after posting about Berea College’s incredible commitment to no-tuition higher education, I actually got around to looking over their website. And I found this:

The Preamble to Berea’s Great Commitments begins, “Berea College, founded by ardent abolitionists and radical reformers, continues today as an educational institution still firmly rooted in its historic purpose ‘to promote the cause of Christ.’ ” The question arises, “Does one have to be a Christian to promote the cause of Christ?” Berea’s historical record says no. [Emphasis added]

So Berea is a Christian school, and its tuition-free model arises directly from what looks to be a highly progressive and inclusive faith statement. If Berea weren’t primarily a teaching school, I might be strongly inclined to look there when it came time for my first faculty position.

College, tuition-free

Photo by blueathena7.

At Berea College in the Kentucky Appalachians, students don’t pay tuition. At all. They’re supported, instead, by working on campus or at the College-owned hotel, and by Berea’s $1.1 billion endowment. The New York Times says that the model is attracting interest from other schools in the era of exploding tuition costs:

… the proportion of low-income undergraduates at the nation’s wealthiest colleges has been declining, as measured by the percentage receiving federal Pell Grants, for families with income under about $40,000. At most top colleges, only 8 to 15 percent of students receive Pell grants.

At Berea, more than three-quarters of the students receive Pell grants.

According to the Times article, Berea’s model comes at the cost of high selectivity (only 22 percent of applicants were accepted this year), and faculty salaries. Nevertheless, Berea is an effective reminder to other American universities that the point of higher education should be to help students improve their lives. And it’s hard to do that if you don’t make a real effort to provide access to lower-income students.

Creationist research: Not just wrong – redundant, too!

Virologist-blogger ERV takes down a Creationist study of bacterial antibiotic resistance, pointing out (1) the methods are flawed, (2) there’s no replication, (3) the interpretation is bogus, and – my personal favorite – (4) someone else has already done the same experiment:

Look, I know relatively little about bacteria. They arent the ‘micro’ in microbiology Im most interested in. But I can do a basic PubMed search to find a paper that analyzed the fitness cost of antibacterial resistance in Serratia marcescens the hard way (ie, the right way): A Fitness Cost Associated With the Antibiotic Resistance Enzyme SME-1 β-Lactamase. [hyperlink from original]