Science online, harm-reducing space squid edition

It’s not easy being green. Photo by Twin Peaks.

Today’s save the frogs day—donate, cut your pesticide use, build a backyard pond, or maybe help an amorous amphibian cross the road.

  • Two (thousand) drifters, off to see the world/ there’s such a lot of world to see … Fire ants cross bodies of water by forming themselves into a raft.
  • Worse than fashion mags. Seriously. Want to give your teenager body image issues? Subscribe to a fitness magazine.
  • Orchids will do anything for pollination. An orchid’s brown-spotted leaves and rotten odor convince flies that the flower is dying from a fungal infection, so they’ll pick up pollen while trying to feed on the fake decay.
  • Babies are smarter than we thought. A classical developmental psychology test turns out not to document a bug in the way human infants think about the world, but a feature of social learning.
  • Harm reduced. The city of Vancouver has dramatically reduced overdose death rates by opening Insite, a facility that allows addicts to use drugs under medical supervision.
  • Cephalopod: A Space Odyssey. NASA will send squids into space on the final flight of the shuttle Endeavour.
  • Introspection with your natural history. Brian Switek muses on the future of science writing.

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The road ahead

Minneapolis, one of my two new hometowns. Photo by jby.

So, now that I’ve defended my dissertation, there’s really not much of grad school left for me. I have to turn in a final, committee-approved version of the dissertation text, and then on May 14 I’ll put on some Hogwarts-worthy getup and accept my diploma from the University of Idaho. I also have some final grading to deal with (Whose bright idea was it to add an independent reading report to the lab curriculum? Oh, right. Mine.) and I’d like very much to get my last Joshua tree paper ready for submission. But, after all that—what’s next?

As it happens, I’ve known that for some time, but there didn’t seem to be a good opportunity to cover it here before now: I’m going to Minnesota.

Specifically, I’ll be starting a post-doctoral position with Peter Tiffin’s lab at the University of Minnesota, Saint Paul. I’m going to be joining a project studying the population genetics of the interaction between plants and nitrogen-fixing bacteria, using the legume Medicago truncatula as an experimental model. It’s a big, multi-lab, multi-institution collaboration, working with genomic data for both Medicago and the bacteria it hosts, Sinorhizobia.

My new favorite plant, Medicago truncatula. Photo by Minette Layne.

So I’ll be studying a mutualism that might work a bit like yucca pollination—but then again, it might not. The plant-rhizobium interaction is much more widespread than obligate pollination mutualism, and has probably played a big role in the diversification of land plants. Plus, I’ll be working with genome-scale data—it’s all on a totally different scale from anything I’ve done before. There are possibilities for experiments and analyses that we’ll never be able to do with Joshua trees—ye gads, greenhouse experiments!—and it’ll be a learning experience at every step. And, equally importantly, my new collaborators at the Tiffin lab and the other research groups involved in the Medicago genome project are a smart, friendly bunch—I’m looking forward to working with them. All in all, it’s exactly what I want in a postdoc.

Saint Paul and Minneapolis look like a pretty nice place to spend the next couple years, too. It’s not just that they’re cities after six years in small-town Idaho—they’ve got solid mass transit and they’re ranked alongside Portland, Oregon for bicycle-friendliness. One of my new senators will be Al Franken. The Twin Cities are the home turf for Public Radio powerhouse American Public Media. Minneapolis was even named the gayest city in America by the Advocate, and I don’t think that was meant as some sort of elaborate joke.

It’s hard to complain about the new neighbors, either: My new U of M colleagues will include George Weiblen, an expert on the other classic obligate pollination mutualism; G. David Tilman, who’s done pioneering work on the ways competition and other species interactions structure natural communities; and Ruth Shaw, who helped lay the foundation for the ways we measure natural selection today. On the science blogging front, none other than P.Z. Myers will be another U of M colleague (at the Morris campus), and BoingBoing’s science guru Maggie Koerth-Baker is in town.

Of course, as I’ve learned from years of Garrison Keillor exposure, winter in Minnesota does not mess around. Fortunately I’m moving immediately after graduation in mid-May, so I’ll have some time to brace myself. Apartment-hunting priorities include covered parking.

All of this is a long and digressive way of saying, yet again, that I’m making some pretty major changes in the next few weeks. Expect further irregularities in posting, and maybe even a radical reconsideration of how D&T fits in my schedule—I don’t yet know what my life will look like once I’ve settled into postdoc-hood, though I’m excited to find out.

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Deprived of pollinators, flowers evolve to do without

Who needs pollinators? Not monkeyflowers—at least not after a few generations of evolution. Photo by Brewbooks.

ResearchBlogging.orgThe loss of animal pollinators poses a potentially big problem for plants. However, many plant species that rely on animals to move pollen from anther to stigma have the capacity to make due if that service goes undone—and, as a new study released online early by the journal Evolution demonstrates, such plants can rapidly evolve to do without pollinators [$a] if they must.

The paper’s authors, Sarah Bodbyl Roels and John Kelly, demonstrate this using a simple greenhouse experiment with the monkeyflower Mimulus guttatus, a wildflower native to western North America, and a member of a genus rapidly developing into a major model system for studying the evolution of ecological isolation and floral evolution.

Mimulus species vary in their reliance on animal pollinators—some grow minimalistic flowers, with the anther so close to the stigma that pollen transfers without any assistance. In natural populations, M. guttatus is usually pollinated by bees, but individual plants vary in the distance between anther and stigma, and this variation has a genetic basis. So a population of M. guttatus deprived of pollinators would have the raw material to evolve a solution—natural selection would favor plants that are better able to self-pollinate. As the population evolved to be more self-fertilizing, it might also evolve to look more like self-pollinating Mimulus species, losing the bright petals that attract pollinators.

To see whether this could actually happen, Bobdyl Roels and Kelly challenged an experimental population of Mimulus guttatus to do without pollinators, and tracked its response.

The authors raised seeds derived from a natural wild population of Mimulus guttatus in greenhouses under two trial conditions: control populations were provided with hives of bumblebees to pollinate them when their flowers were ready for servicing; and experimental populations were left to produce what seed they could without pollinators. The authors collected the seeds produced by each population, and planted them to form the next generation.

A bumblebee digs for nectar in flowers of Mimulus moschatus. Photo by Mollivan Jon.

Early on in the experiment, the experimental populations deprived of pollinators fared badly. Without pollinators, the average plant produced two seeds or fewer by the end of the generation, compared to eight or ten seeds per plant in the population provided with bees. By the fifth generation, however, this was starting to improve—plants in both populations without pollinators were producing more seeds, and one of the two experimental populations produced nearly as many seeds as the control plants.

Examining the traits of plants produced by this final generation (actually, the grand-offspring of the fifth generation, to control for effects of inbreeding), the authors found that the average distance between the pollen-producing anther and the pollen-receiving stigma had shrunk significantly in plants from the experimental population. Across all the treatments, plants with a shorter distance between stigma and anther produced more self-pollinated seeds. There was no evolved change in other floral measurements, however—plants in the no-pollinators treatment had petals as big and showy as plants evolved with bumble bees.

In a natural population of Mimulus guttatus, the drop-off in seed production created by loss of pollinators should have much the same effect as in this experiment, creating a strong selective advantage for individual plants that can make more seeds on their own. The fact that the experimental plants did not evolve reduced petals could mean that in the cushy conditions of a greenhouse, there wasn’t much need to stop spending resources making showy flowers. Or maybe, when the major source of natural selection is the need to make any seeds at all, selection to save resources on flower production is relatively weak and correspondingly slow-acting.

As the authors point out, one of many changes humans are making to natural communities around the world is to disrupt pollination relationships. In a sense, experiments like theirs are being carried out worldwide, on hundreds of plant species—and each species will adapt, or fail to adapt, in its own way.

Reference

Bodbyl Roels, S., & Kelly, J. (2011). Rapid evolution caused by pollinator loss in Mimulus guttatus. Evolution DOI: 10.1111/j.1558-5646.2011.01326.x

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Science online, back online edition

Suck it, tigers. Photo by Billtacular.

I didn’t do a linkfest last week, what with having other things on my mind, so this list may be longer than average. You should read them all.

  • Converging … on poison! Both bird’s foot trefoil and the burnet moth caterpillars that eat it have independently evolved the ability to synthesize two cyanide-based toxins.
  • Not what you want to read the week you defend your Ph.D. A guy who anticipated two previous economic bubbles thinks that the next one to burst could be higher education.
  • Born free, but do they want to stay free? Whether animals are happier in the wild depends on what kind of life they could have in captivity.
  • Better offense and better defense. How “natural” resistance to HIV infection works, on a cellular level.
  • “Third gender” ≠ “gay.” The many ways modern cultures grapple with human sexual diversity shed light on the “gay” non-caveman.
  • Also less cute, in my opinion. When you consider their respective ecological roles, tigers are less important than warblers.
  • Unhappy anniversary. A year after the Gulf of Mexico oil spill, we still don’t know what effects the oil and chemical dispersants may have on sea life—but there are plenty of reasons to worry.
  • Your wardrobe, under the microscope. Anthropological consideration of why women (and men) wear high heels, as well as why those heels might be black.
  • Shakespeare, evolution, and Kubrick’s Space Odyssey: brilliant. Brutish, aggressive chimpanzees have long been the assumed model for earlier humans—but more peaceful bonobos might be closer to the truth.
  • Might as well give up on drug development right now. Masturbation (or, rather, orgasm) has been found to relieve restless leg syndrome.
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What’s in that dissertation, anyway?

About to take the plunge. Photo by jby.

So, what with getting my sparrows in a row for my dissertation defense on Friday, I haven’t written any new science post for this week. But! As it happens, I have written about most of the component chapters of my dissertation—so in lieu of something new this week, why not check out those posts?

  • The first chapter of my dissertation is a literature review about the phenomenon ecologists call ecological opportunity, and how it may or may not explain big, rapid evolutionary changes. I’ve also written about this topic for the Scientific American guest blog.
  • The second chapter uses phylogenetic methods to reconstruct what yucca moths were like before they were yucca moths.
  • The third chapter presents a mathematical model of coevolution between two species, and determines what kind of interactions—predation, parasitism, mutualism, competition—can cause those species to evolve greater diversity.
  • The fourth chapter is the latest work on my lab’s big study of Joshua trees and their pollinators. The material I’m including in this chapter hasn’t been reviewed and published yet, but you can read the most recent Joshua tree post to learn what we know so far, and what kinds of questions we still want to answer.

Regular posting resumes next week, provided that I pass my defense and the celebrating afterward doesn’t interfere with my blogging capacity.

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Science online, bracing for impact edition

Ho-hum. Photo by v1ctory_1s_m1ne.

A week from today, I defend my dissertation. Fortunately, Eric Michael Johnson pointed out to me that the most worrisome possible question has been answered. So I’m all set!

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Defending my dissertation

A week from Friday, I’m finally going to present six years’ worth of doctoral research to my dissertation committee, and they’ll tell me whether or not it’s enough to warrant a Ph.D. I am given to understand that the process will go something like this:

Which is to say, a lot of frantic running around culminating in a highly formalized event at which my fate will depend on answering potentially arbitrary questions. Maybe involving swallows.

I’m still in the running-around bit, which involves tasks like taking my written dissertation to have the College of Graduate studies check the width of the page margins. So, um, wish me luck.

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Queering ecology

Eastern bluebird, car. Photo by Automania.

Via Kate Clancy at Context and Variation: Alex Johnson takes a look at the way we think and write about the natural world, and finds it wanting.

Our culture sets Nature as the highest bar for decorum, while simultaneously giving Nature our lowest standard of respect. Nature is at our disposal, not only for our physical consumption, but also for our social construction. We call geese beautiful and elegant and faithful until they are shitting all over the lawn and terrorizing young children. Then we poison their eggs. Or shoot them.

Having popped the naturalistic fallacy with a few pokes, Johnson proposes queering ecology—a deliberate reference to the term’s usage in human sexuality—to better acknowledge the complications of the natural world and humans’ relationships to it. That summary doesn’t do the work justice, though—go read the whole thing.

(Kate linked to this more-or-less alongside my first volley in the old adaptive homophobia kerfuffle, but Johnson’s essay is another order of thought altogether. Also, how cool is it that I can just go to Flickr and find an illustration for Johnson’s point with a simple keyword search? Pretty cool, I think.)

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How can you tell if a plant is carnivorous? Feed it!

A Venus flytrap closes on an unfortunate spider. Photo by cheesy42.

ResearchBlogging.orgPlants that eat animals offend our trophic sensibilities. Those of us who can move independently are supposed to eat those of us who can make sugar from sunlight—that’s just the way the food chain works, right?

Well, not really. From a certain perspective, plants prey on animals all the time, using the sneaky strategy of just waiting us out—when we animals stop moving for good, we’re fertilizer. And there are quite a few plants that aren’t so patient. Venus flytraps, sundews, and pitcher plants have been recognized as carnivores since before Charles Darwin devoted a book to their ecology and anatomy. They all have structures—fly-trapping leaves, or sticky hairs, or deep pitfalls full of water—that are uniquely good at catching wayward insects. All of them also grow in particularly nutrient-poor soils, such as bogs, where the nitrogen from trapped insects makes a big difference.

The vast majority of plants lack either adaptations for trapping, or the same kind of need for nitrogen—they either don’t grow where they can’t get the stuff, or they hire symbiotic bacteria to help fix it. Yet there is a third category of plants, which are not exactly carnivorous, but which might just “eat” the occasional stray fly anyway. Many plants have hairy surfaces that can catch insects, or leaf structures that trap water and create pitfalls—and some of these plants can take advantage of the critters caught in these proto-traps.

Sticky purple geranium can trap insects on its sticky leaves, and seems to get some nutrition out of them. Photo by jby.

One such plant is the sticky purple geranium (Geranium viscosissimum), which grows on dry Palouse hillsides around my current hometown of Moscow, Idaho. As its name implies, sticky purple geranium is sticky—its leaves are velvety with tiny glandular hairs, which leave a gummy residue on your hands if you brush against them. These hairs make it difficult for small insect herbivores to get to the leaves—but they also trap some of those insects.

Back in 1999, a biologist in my department at the University of Idaho, George Spomer (who left the department before my arrival), showed that sticky purple geranium leaves would digest a protein film pressed against them, somewhat like the leaves of a sundew. When Spomer placed protein labeled with carbon-14 on geranium leaves, he found elevated levels of carbon-14 elsewhere in the plant, suggesting that geranium leaves could absorb protein as well as digest it [$a].

Spomer demonstrated that the plants he studied could digest and absorb insects caught on their leaves, but his data can’t tell us whether that ability is of any particular use to a geranium growing in a natural population—whether, that is, geraniums actually need the nutrients they might get from trapped insects. A more recent study of another possibly carnivorous plant gets closer to answering that question.

Water collected in the leaves of a teasel plant forms a death trap for insects, and a source of nitrogen for the plant. Photo by HermannFalkner/sokol.

The plant in this second study is fuller’s teasel, Dipsacus fullonum, a widespread European wildflower that has been introduced into North America. The leaves of many teasel plants form catchments (pictured above) that can collect water and form a makeshift pitfall, which catches and drowns small insects. It has been speculated that, like sticky purple geranium, fuller’s teasel can absorb nutrients from these catchments full of rotting insect corpses. British biologists Peter Shaw and Kyle Shackleton set out to test this hypothesis not by tracking protein from trapped insects, but by determining whether teasel plants benefit from the trapping.

To do this, Shaw and Shackleton experimentally manipulated the number of insects trapped in the catchments formed by teasel plants’ leaves. In one treatment, they watched experimental plants and removed insects as soon as they were trapped; in the other, they “fed” the experimental plants an extra bluebottle maggot at set intervals. They compared both treatments to a group of plants that were left un-manipulated as a control. The “fed” plants didn’t necessarily grow bigger or produce more seeds, but they did produce more seeds as a proportion of their total biomass. That is, fuller’s teasel plants that trap more insects can devote more of their resources to making seeds.

Does this make fuller’s teasel carnivorous? Maybe, but probably not in the same sense that a Venus flytrap is. Teasels tend to grow in better soil than carnivorous plants do in general—they like open fields and stream banks, in my experience. Furthermore, we don’t have any evidence that teasels actively attract insects, as most carnivorous plants do. On balance, it seems far more likely that what Shaw and Shackleton found is not carnivory as we usually know it, but plants making sure that a handy source of nitrogen doesn’t go to waste.

Fuller’s teasel relies on insects for pollination—but does it also rely on them for nutrition? Photo by gynti_46.

References

Darwin, C. (1875.) Insectivorous plants. Google Books link.

Shaw, P., & Shackleton, K. (2011). Carnivory in the teasel Dipsacus fullonum — The effect of experimental feeding on growth and seed set. PLoS ONE, 6 (3) DOI: 10.1371/journal.pone.0017935

Spomer, G. (1999). Evidence of protocarnivorous capabilities in Geranium viscosissimum and Potentilla arguta and other sticky plants. Int. J. Plant Sci., 160 (1), 98-101 DOI: 10.1086/314109

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