Monthly Archives: June 2009

When plant siblings play nice, everyone loses

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ResearchBlogging.orgA couple years ago, scientists studying the wildflower American searocket, noticed something funny: when grown in the same pot with sibling seeds, searocket plants grew smaller roots than they did when sharing a pot with unrelated plants. It looked as though searocket plants recognized their siblings, and tried not to compete with them.

If this were a widespread phenomenon, it could dramatically change how biologists think about plant’s evolution and ecology. Right now, we think that the huge diversity of seed dispersal mechanisms — from fruit, to ballistics, to ants — evolved at least in part to minimize competition between sibling plants. But if plants can recognize and preferentially accommodate their siblings, clusters of related plants might actually improve their collective fitness — or rather the fitness of the genes they share.


Lupinus angustifolius
Photo by enbodenumer.

A new paper in Proc. R. Soc. aims to test the hypothesis that sibling recognition boosts plants’ collective fitness. The authors conducted a more precise version of the original kin recognition experiment, planting seeds from common European lupines (Lupinus angustifolius, pictured) alongside their siblings, unrelated seeds from the same source population, or unrelated seeds from a distant population. They then measured a variety of fitness traits to determine whether individual plants benefited from growing near siblings, or whether sibling groups performed better collectively than groups of unrelated competitors.

The results were pretty clear — in staying out of each other’s way, sibling plants had lower individual and group fitness. Plants growing near siblings produced fewer fruits and seeds than those growing near non-relatives, and groups of siblings collectively produced fewer fruits and seeds than groups of unrelated plants. This suggests that the kin recognition effect may actually contribute to selection for better seed dispersal, rather than provide a benefit for growing together.

References

Dudley, S., & File, A. (2007). Kin recognition in an annual plant. Biology Letters, 3 (4), 435-8 DOI: 10.1098/rsbl.2007.0232

Milla, R., Forero, D., Escudero, A., & Iriondo, J. (2009). Growing with siblings: A common ground for cooperation or for fiercer competition among plants? Proc. R. Soc. B, 276 (1667), 2531-40 DOI: 10.1098/rspb.2009.0369

Things I learned today

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Spent the better part of this afternoon taking apart my bike and putting it back together. My barely-competition-worthy Trek Pilot now has a full Ultegra drivetrain! It was an intensely, satisfyingly educational experience, worthy of reduction to a bullet list of insights:

  • Ebay really can save you money. Total cost of a “complete” Ultegra double/nine speed group: up to $900. Total spent bidding for individual components over about three months, including additional parts purchased at the local bike shop: $450.
  • Buying things a piece at a time on Ebay is tricky. For instance, if you purchase your crank set separately from your bottom bracket, the bolts needed to connect them are probably going to be included with neither.
  • Living near a bike shop is vital. I made three different trips to a shop barely a mile away — once for the aforementioned bolts, once for spacers necessary to make my new nine-speed cassette fit where my old eight-speed one had gone, and once to remove an impossibly well-stuck-on old bottom bracket. Really, it would’ve been better if they were just across the street.
  • Tools matter. Using the bottom bracket socket wrench attachment in my “everything you need” bike toolkit, I spent half an hour grunting and pulling on my old bottom bracket, to no obvious effect. When I took it in to the bike shop, the mechanic had it off in thirty seconds using a dedicated bottom bracket tool with a proper integrated handle.
  • Fixing a bike boils down to using an Allen wrench repeatedly. Which is to say, given the right references (I used Zinn and the Art of Road Bike Maintenance and some strategic Google searching), even installing new brake/shift levers was pretty easy.
  • Knowing the right people is also vital. When everything was bolted on and connected up, I couldn’t get my derailleurs tuned. That could’ve meant a days-long wait till the bike shop had time to take the job, but serendipitously, I got an IM from a fellow cycling club member with more mechanical chops just as I was giving up. I took the bike to his place, and between the two of us we had it operational in half an hour.
  • Learning by doing works. I’m not going to claim expertise after this, but I’m now that much less likely to throw up my hands and run to the shop the next time there’s a problem with the bike.

All in all: not a bad way to spend a Sunday. Shakedown ride is tomorrow morning.

So many links, so little time

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Walking the Jesus Trail

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The Washington Post has a great piece, with photos, on the Jesus Trail, a hiking path through northern Israel that connects the wealth of Biblical-historical texts related to stories in the Gospels. Although the subject matter is the life of Christ, it’s an attempt to bring together all three of the Abrahamic faiths — the guesthouse that anchors the trail in Nazareth is a joint venture between an Israeli Jewish manager and an Arab family that’s been there since before 1948.

One of the trail’s architects is my old college friend Dave Landis — we were on a university cross-cultural trip to Israel and Palestine together back in 2002, and spent a week backpacking in the region the Jesus Trail now traverses. Dave’s had a special interest in the much-contested Holy Land ever since. His site has lots more photos.

Familiarity breeds contempt: Mockingbirds recognize and react to repeat intruders

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ResearchBlogging.orgHumans are a fact of life for many, many parts of the natural world. This doesn’t always have to be a bad thing — some critters adapt to human-dominated landscapes pretty well. A paper in this week’s PNAS, for instance, shows that Northern Mockingbirds nesting on a busy university campus learn to differentiate between uninterested passers-by and people who repeatedly disturb the nest site [$-a].


Northern Mockingbird with fledglings
Photo by mjmyap.

When potential predators come too close to a nest, wild birds try to distract the threat with harassing alarm calls, diving attack flights, or “flushing” to draw attention away. This doesn’t work so well if you’re nesting near a busy sidewalk; you’d spend all you time trying to drive off passers-by who pose no real threat. And, as Levey et al. show in the new paper, mockingbirds seem to have solved this problem by reacting more strongly to people who approach the nest repeatedly.

The experimental evidence is elegant: Individual researchers approached occupied mockingbird nests on four consecutive days, and recorded the birds’ reactions. The birds flushed farther, gave more alarm calls, and attacked more often with each repeat visit. When a new person approached the nest on a fifth day, though, the birds’ reactions were equivalent to their behavior on the first day. Furthermore, nesting mockingbirds flushed farther if their nests were near less-busy sidewalks. This isn’t evidence for an evolved response, but for learning; and it suggests that mockingbirds are able to recognize individual humans, and apply that familiarity in assessing the danger posed when someone approaches the nest.

This is just one example of the evolved and learned adaptations the living world has made in response to human activity. Last year, for instance, a study showed that a French wildflower has evolved wingless seeds in response to urban growing conditions — although winged, wind-dispersed seeds do better in the wild because they’re less likely to compete with their siblings, in a heavily paved environment the best spot to germinate is more likely to be close to the parent plant. And perhaps one of the best-known examples of natural selection in action is the increased frequency of dark-colored peppered moths in response to industrial pollution. Nature is nothing if not flexible.

References

Cheptou, P., Carrue, O., Rouifed, S., & Cantarel, A. (2008). Rapid evolution of seed dispersal in an urban environment in the weed Crepis sancta Proc. Nat. Acad. Sci. USA, 105 (10), 3796-9 DOI: 10.1073/pnas.0708446105

Grant, B.S., Owen, D.F., & Clarke, C.A. (1996). Parallel rise and fall of melanic peppered moths in America and Britain Journal of Heredity, 87, 351-7 DOI: http://jhered.oxfordjournals.org/cgi/content/abstract/87/5/351

Levey, D., Londono, G., Ungvari-Martin, J., Hiersoux, M., Jankowski, J., Poulsen, J., Stracey, C., & Robinson, S. (2009). Urban mockingbirds quickly learn to identify individual humans Proc. Nat. Acad. Sci. USA, 106 (22), 8959-62 DOI: 10.1073/pnas.0811422106

The benefit of the doubt

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Regarding Sunday’s shooting of abortion-providing doctor George Tiller, in the lobby of his church, by a professed pro-lifer, Slacktivist says it best, reflecting on a similar shooting, and the similar responses it elicited, in 1994:

These were groups that routinely spoke of abortion as “murder” or “mass-murder,” and that routinely spoke of legalized abortion as an “American Holocaust.” They had, for years, been using precisely the same rhetoric and making exactly the same arguments that Paul Hill was now using to attempt to justify his [1994] double homicide.

Those groups’ condemnations of Paul Hill then — like their condemnations of [Tiller’s alleged killer] Scott Roeder now — ring hollow. Such condemnations seem to be self-refuting. How can they condemn men like Hill or Roeder just for taking their own arguments seriously?

Thought experiment: if anti-abortion groups were Muslim and said the things they said, and a professed Muslim followed through and shot someone, would it even occur to the American political classes to take said groups’ word that they never meant to call for actual violence?

Carnival of Evolution #12 at Deep Sea News

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Deep Sea News has the latest issue of the Carnival of Evolution, rounding up the blogosphere’s discussion of descent with modification over the last month. Highlights include GRRL Scientist’s review of Jerry Coyne’s new book, Blag Hag’s snarky deflation of anthropocentrism, and Greg Laden’s analysis of some fossil primate of which I hadn’t previously heard.