Having their cake and eating it, too


Photo by Ben McLeod.



Mennonites in the marketplace







Ecological differences divide Mimulus guttatus

ResearchBlogging.orgReproductive isolation is the engine of evolutionary diversification. When two populations become unable to exchange genes, they’re effectively separate species, free to evolve on independent trajectories.

Biologists have documented many examples of reproductive isolation arising from all sorts of different interactions between organisms and their environments, including incompatibilities between gametes, adaptation to different pollinators (in plants), or the evolution of different sexual characteristics. The cover article for this month’s issue of Evolution describes another way reproductive isolation can arise – adaptation to different environments.

Mimulus guttatus
Photo by Dawn Endico.

The new paper, by Lowry et al., describes how different ecological conditions create reproductive isolation where there would otherwise be none [$-a]. The wildflower Mimulus guttatus grows all along the U.S. Pacific Coast. Some Mimulus populations grow inland, in coastal mountains, where the summers are hot and dry; others grow right on the coast, where fog provides moisture but plants have to tolerate salt spray from the sea. Plants from inland and coastal populations look quite different (inland = tall with big flowers; coastal = short with small flowers), and have previously been separated out into different subspecies. But are they actually isolated?

Lowry et al. found that inland and coastal plants perform poorly when transplanted to the others’ habitats, and that they flower at significantly different times. A population genetic analysis shows that the coastal and inland populations don’t exchange genes very often. But it’s possible to hybridize the two types in the greenhouse. In short, it looks like Mimulus is a case of what Nosil et al. called “immigrant inviability” [$-a]. Immigration between inland and coastal sites may be possible, and immigrants would (theoretically) be able to reproduce if they mated with plants from the local population – but before they get a chance, they’re nailed by summer drought (at inland sites) or salt spray (at coastal sites). So even before they’ve evolved fundamental incompatibilities, these two types of Mimulus are well on their way to being separate species.


D.B. Lowry, R.C. Rockwood, J.H. Willis (2008). Ecological reproductive isolation of coast and inland races of Mimulus guttatus. Evolution, 62 (9), 2196-214 DOI: 10.1111/j.1558-5646.2008.00457.x

P. Nosil, T.H. Vines, D.J. Funk (2005). Reproductive isolation caused by natural selection against immigrants from divergent habitats. Evolution, 59 (4), 705-19 DOI: 10.1554/04-428


Like crack for politics geeks

FiveThirtyEight.com has taken up a lot of my internet-surfing time since On the Media interviewed its founder, Nate Silver. FiveThirtyEight (which takes its name from the number of votes in the US electoral college) takes a new approach to poll-crunching, using simulated election results drawn from current polling to develop what looks like (to my not-very-statistically-savvy) a Bayesian estimation of the electoral votes for Barack Obama.

The nuts and bolts of the simulation model aren’t completely exposed in the FAQ, but it apparently takes into account the past accuracy and biases of each poll used, as well as demographic similarities between states. There’s lots of data on display, including the probability distribution of possible electoral outcomes – which currently projects an Obama victory in 72.4% of simulations.


Democrats are better for the economy than Republicans

Slate has a new infographic that compares U.S. economic performance metrics under Democratic and Republican presidents from 1957 to 2007. On almost every measure, Democrats are ahead. This follows up on a New York Times piece from a few weeks ago that came to similar conclusions, including that income inequality tends to decrease under Democratic presidents:

It is well known that income inequality in the United States has been on the rise for about 30 years now … Over the entire 60-year period [from 1948 to 2007], income inequality trended substantially upward under Republican presidents but slightly downward under Democrats, thus accounting for the widening income gaps over all.


Requiescat: David Foster Wallace

David Foster Wallace, author of innumerable wise, hilarious, occasionally esoteric essays and the incredible novel Infinite Jest (among other works), was found dead Friday in his California home. McSweeney’s Internet Tendency is soliciting remembrances. Over on Flickr, Steve Rhodes, from whom I’m borrowing the photo below under Creative Commons licensing, has a long list of links to DFW’s work and other resources.

Photo by Steve Rhodes.

Wallace was uniquely able to capture everything that is beautiful and foul in millennial American culture – one of my favorite examples is this snippet from Infinite Jest, in which a satirical representation of a U.S. cabinet member refers to people fleeing a (possibly government-created) environmental catastrophe:

Absolutely not, Mart. No way a downer-association-rife term like refugee is going to be applicable here. I cannot overstress this too assertively. Eminent nondomain: yes. Renewal-grade brand of sacrifice: you bet. Heroes, new era’s breed of new pioneers, striking in bravely for already-settled good old settled but unfoul American territory: bien sûr.

This, of course, was written something like a decade before the Hurricane Katrina-created controversy over the application of the term refugee to Americans. Which, to my mind, makes DFW a prophet in both the popular (if incorrect) sense of actually foreseeing the future as well as the correct sense of speaking truth that the world needs to hear. The world is a darker place without him.