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June 28, 2012

Evolutionary tradeoffs and drought-tolerant crops

The Union of Concerned Scientists recently sent me a link to a report arguing that "Genetic Engineering is not Solving Agriculture's Drought Problem." This is an issue I address in detail in my book on Darwinian Agriculture, which will be available at the upcoming Evolution Meetings in Ottawa and more widely by the end of July.

Briefly, my argument is that mutant plants with greater or less expression of existing genes must have arisen repeatedly over the course of evolution. Some of those mutants were presumably more drought-tolerant than their parents, while others were less drought-tolerant. If there were no disadvantages to a given drought-tolerance gene, then plants with that gene took over. Repeat this process of natural selection for millions of years, and there may be few remaining opportunities for further improvements that are both simple (i.e., achievable by the sort of mutations that arise reasonably often) and tradeoff-free (never having negative effects on fitness, at least in past environments). My book therefore raises doubts about increasing the expression of existing plant genes to improve drought tolerance.

This argument applies to conventional breeding, not just genetic engineering. Another key point is that some tradeoffs rejected by past natural selection may be acceptable in an agricultural context. In fact, accepting acceptable tradeoffs may often be the fastest route to progress.

It's not entirely clear, however, whether my concerns above apply to the particular transgenic crop discussed in the Union of Concerned Scientists report. Monsanto's "DroughtGard" corn (maize) contains a gene derived from bacteria. Does this gene result in a phenotype very different from any seen in the recent evolutionary history of corn? If so, then we can't assume that this approach to drought tolerance has been repeatedly rejected by past natural selection. It may never have been tested by natural selection. Rather than rejecting it on theoretical grounds, therefore, we would need actual field data to determine the advantages or disadvantages of this transgenic variety.

Of course, those data would need to come from independent tests, not run or paid for either by Monsanto or by one of their commercial competitors. Agricultural universities run such tests every year, comparing crop varieties developed by different companies and by public-sector plant breeders. I look forward to seeing how DroughtGard does in such tests.

June 21, 2012

Two upcoming meetings

The Society for Molecular Ecology and Evolution is holding their annual meeting June 23-26, in Dublin. Two graduate students from the lab of Mike Travisano, with whom I collaborate, will discuss their recent research:

On Monday, June 25th, Maria Rebolleda-Gomez will speak on the: "Molecular basis of increased evolvability as a result of multicellularity evolution"

On Tuesday, June 26th, Johnathon Fankhauser will discuss: "Decoding the genomic and transcriptional changes underlying the transition to multicellularity in experimentally-evolved Saccharomyces cerevisiae."

At the same meeting, Chelsea Du Fresne, an undergrad, will present poster 2386: Emergence of multicellular novelty

Next comes the 1st Joint Congress in Evolutionary Biology, July 6-11 in Ottawa.

On July 7, Will Ratcliff will speak on "Evolution of accelerated aging after the transition to multicellularity"

That evening, Mike Travisano will present a poster titled "Re-evolving the Volvox?"

On Sunday, July 8, I will speak on "Measuring effects of symbiosis on fitness of legumes and rhizobia."

My new book on "Darwinian Agriculture" will supposedly be available at the Ottawa meeting, at the Princeton University Press table, if anyone wants an autographed copy.

The MicroPop (Microbial Population Biology) website has more information on our current research.

June 11, 2012

Multicellular Yeast Defeats Rotifer

I really like this movie Will Ratcliff made, showing one of the benefits of being multicellular.


The rotifer at the right easily consumes single-cell yeast, but our lab-evolved multicellular yeast was more than it could handle. See our open-access paper in Proceedings of the National Academy of Sciences for scientific details and the Travisano/Dean/Denison Microbial Population Biology website for more videos.

Mike Travisano and Will Ratcliff, principal investigator and super-postdoc, respectively, on the multicellularity project, will have a poster and talk at the upcoming Evolution Meetings in Ottawa.

June 8, 2012

Scientific tourism in Hawaii: beyond beeches

The big event was the June 5 transit of Venus across the sun. Our estimates of cosmic distances (size of the galaxy, etc.) depend on estimates of the distance to the nearby stars, which depend on knowing the length of the earth's orbit, which were first estimated from differences with latitude in the duration of the 1761 and 1769 transits. TransitOfVenus.JPG
My brother-in-law, Dean Nomura, took the photo above (near the end of the transit) from Oahu, Hawaii, using his video camera and my Kendrick solar filter. With the same filter on my Celestron 70 mm travel telescope, we could also see four large sunspots not visible in this photo (see NASA photo on Wikipedia). For those without telescopes, the University of Hawaii's Institute for Astronomy provided telescopes and safe-viewing filters at several locations. Venus was visible (barely) without magnification.

There won't be another transit of Venus visible until 2117, at least from Earth. But you could save up for a trip to Mars, to view the 2084 transit of Earth. This assumes fundamentalists don't re-impose burning at the stake for questioning an Earth-centered view of the solar system before we develop the ability to travel to Mars.

Meanwhile, Hawaii has plenty of less-ephemeral opportunities for scientific tourism. Past trips have include snorkeling with sea turtles, getting as close to flowing lava as my heat tolerance would allow, and an impromptu discussion with a technician who maintains research mini-subs. Also lots of cool plants, on hikes and in several great botanic gardens. This time, we hiked above the Hawaii Nature Center (trails shown on Google maps!) and got lost (briefly) at the Ho`omaluhia Botanical Garden. We also signed up for a tour of Kahuku Farms, perhaps the only farm in the world that rotates between eggplants and papaya.
They also grow bananas, lilikoi, and various flowers.

I I particularly enjoyed seeing their huge Casuarina trees, which they called "ironwood." Hawaii has lots of legumes (including the "sensitive plant" and many trees), many of which host nitrogen-fixing rhizobia. Casuarinas also host nitrogen-fixing symbionts, but they aren't legumes and their symbionts aren't closely related to rhizobia. Casuarinas are related to beeches, but they look remarkably like conifers, with needle-like leaves and cone-like flowers. To see the resemblance, look at a Casuarina photo (with a sea turtle laying eggs in the background) posted previously, which I took on Heron Island, during the Applied Evolution Summit.

If you find yourself in Hawaii without bird, plant, and hiking books, the central library in downtown Honolulu is wonderful -- lots of classic science fiction and shaded courtyard -- and the branch libraries aren't bad. You can buy a guest membership if you want to use their internet access or borrow a book.