Category Archives: evolution

Principle interviewee: Erica Bree Rosenblum

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This post was chosen as an Editor's Selection for ResearchBlogging.orgSince her office is just down the hall from mine, I couldn’t very well write about Erica Bree Rosenblum’s latest scientific paper without talking to her about it in person. Rosenblum and her coauthor Luke Harmon weave together the stories of three lizard species’ evolutionary responses to the gypsum dunes of White Sands, New Mexico. As Rosenblum told me in our interview, the study both consummates work she began as a doctoral student and suggests new avenues of study at a striking and beautiful field site.

Erica Bree Rosenblum at White Sands, where she has studied lizards’ adaptation to the dramatic gypsum dunes since graduate school. Photo courtesy Erica Bree Rosenblum.

(I’ve edited the transcribed interview for clarity and length, and paraphrased the questions I asked in person to minimize my interruptions. Rosenblum previewed, corrected, and approved the text of her answers and my questions as they appear below.)

Jeremy B. Yoder: Tell me about the new study and its context.

Erica Bree Rosenblum: Some of the things that are compelling about White Sands that motivated us to write the “Same Same but Different” [$a] are that there are a number of different species that colonized this recent formation. … At first blush, this system looks all “same same.” You look at the main trait that has allowed these animals to survive there, which is becoming light in color, and many diurnal animals at White Sands are white, unless they have some other strategy for avoiding predation. … So a lot of my work over the last several years has been focused on the “same same” aspect of convergent evolution and on the one trait that appears to be the key trait for colonizing, which is light color.

The motivation of this paper was that there is an enormous “but different” side to the story, because there are three lizard species there, and they exhibit some really compelling differences in their degree of adaptation and their progress toward speciation. And also if you start looking at other traits besides color, if you take a multidimensional perspective on adaptation, then there are a lot of really striking differences across species.

JBY: Body size and limb length?

EBR: Body size and limb length and also the genetic basis of color and how structured the populations are across the ecotone. [The transition zone between white sand dunes and dark soil – JBY] So the motivation for this study was to look at what are the essential factors for ecological speciation and then what are the promoting factors for ecological speciation and how might the three species differ.

JBY: How did you start studying the White Sands lizards in the first place?

EBR: I was co-advised in graduate school by two eminent evolutionary biologists who have opposite perspectives on how you find study systems. My first year in graduate school, my one advisor, Craig Moritz, said to pick the theory you are interested in first and then find the system that will let you address that theory. My other advisor, David Wake, said to pick something that you love aesthetically, and then learn more about that. So I had these competing influences, in that sense, when I was trying to form my dissertation project.

Rosenblum and her collaborator Luke Harmon pursue Sceloporus magister, a close evolutionary relative of one species that has colonized White Sands. Photo courtesy Erica Bree Rosenblum.

I had just come back from a bunch of years abroad, and I knew I didn’t want to do research overseas. I also knew that I wanted to do my own thing and just “plug into” a system that had already been established. So I had an idea for wanting to do a study about ecotones—to study divergence with gene flow—in herps. [Lizards and snakes – JBY]

I had talked with different people and taken a map of the U.S. and circled every place that had really sharp transition zones that had to do with interesting problems in herpetology. So I had considered other field sites—in some of the lava flows in California that have strong transition zones, coastal-to-inland [transitions], these cool legless lizards in California—there’s a bunch of strong ecotonal transitions in western U.S. reptiles.

So I circled a bunch of places on the map and I was driving around catching animals and thinking about what I wanted to do. And when I got to White Sands, the Dave Wake part of me was drawn to it aesthetically. … It just seemed like such a striking example of adaptation with such clear possibilities. I knew I wanted to study something simple enough to wrap my head around, and White Sands has a striking, small, depauperate community, so you can actually study everything. And with a few exceptions, no one had done any biological research at White Sands since the forties, when the White Sands species were described.

JBY: What question would you like to have answered five years from now?

EBR: One of the big things I’d like to know is about the dimensionality of selection in the wild. We have a tendency to think about whatever trait seems most accessible to us, but when environments change, organisms are confronted with a lot of adaptive problems to solve at once.

… Number one is understanding the genetic architecture of adaptation and speciation. We know a lot about genotype to phenotype connections in natural populations, but we don’t know a lot about genotype-to-phenotype-to-speciation connections. I’m really interested in traits that might function as “magic traits,” that make speciation easier. I’m interested in whether [for White Sands lizards] color serves as a magic trait and can “high-tail” populations towards speciation.

The other thing I’m interested in is the genetic architecture of multidimensional adaptation. If you have lots of traits that are changing in a new environment, and it is happening very quickly over time, are the genes that underlie those adaptive traits all clustered in the genome? Is there a “signature” of multidimensional adaptation at the genetic level?

And then the third thing is about the predictability of evolution in general. I think it would be really fun to do a more systematic study of the entire fauna at White Sands and understand not just three lizard replicates but all the other species that are white, from invertebrates to mammals, to understand how predictable those adaptive changes are.

Different shades of Sceloporus undulatus, one of the three lizard species adapted to life at White Sands. Photo courtesy Simone Des Roches.

JBY: What about ten years from now?

EBR: The challenge of working at White Sands is that it’s a compelling empirical system to test some classic population genetics ideas, but it’s very hard to develop general conclusions from one system with three replicates. It’s nice to have the three lizard replicates, but it’s still only one system in one place. I’ve tried to visit all the other gypsum sand dune systems in the world. There are others—in Texas, in Mexico … they have unique faunas in other ways, but none of them seem to have blanched species. So when you study natural systems, finding compelling evolutionary replicates can be difficult.

JBY: And when we go looking for study systems we often find the ones with the strongest signals first.

EBR: That’s right … Another example where we’re running into a problem is that … in two of the three species the gene that controls color is the same gene, but has different dominance patterns [PDF]. In one species the mutation that leads to white color is recessive and in the other it’s dominant. And there’s a longstanding debate from Haldane, of how dominance should influence adaptation, but it’s just an N of two. So we could get any pattern. We’re doing follow-up studies to see if the predictions would be upheld in terms of how dominance affects the rate at which adaptive alleles are fixed, and visibility to selection. But whichever way the story goes, it’s either the way you expect it or the way you don’t expect it, but it’s just two replicates. So that is one challenge of studying things in nature.

JBY: Let’s conclude with an outrageous, blog-oriented question: Is White Sands the new Galapagos Islands?

EBR: Yes. [Laughs]

JBY: That’s what I hoped you’d say.

EBR: There are things that are compelling about white sands not only for learning about evolution but also for teaching about evolution. One of the new grants I have is for integrating research and outreach there, because it’s such a compelling place to say, “this is how adaptation happens.” You can see it with your eye, and it’s exactly what you expect. We just finished helping build a new evolution museum at the visitor center at white sands. … So I think that it has cool potential for helping public education around evolution, and it’s not as expensive to go there as it is to go to the Galapagos!

References

Rosenblum, E., Rompler, H., Schoneberg, T., & Hoekstra, H. (2009). Molecular and functional basis of phenotypic convergence in white lizards at White Sands. Proc. Nat. Acad. Sci. USA, 107 (5), 2113-7 DOI: 10.1073/pnas.0911042107

Rosenblum, E., & Harmon, L. (2010). “Same same but different”: Replicated ecological speciation at White Sands. Evolution DOI: 10.1111/j.1558-5646.2010.01190.x

For lizards on white sands, evolution doesn’t quite repeat itself, but it does rhyme

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ResearchBlogging.orgSee also my interview with Erica Bree Rosenblum, the lead author of the study discussed here.

If life on Earth started over from scratch, would it eventually re-evolve the world we see today? This is the kind of question that makes for an entertaining argument over beers: “Well, without the Chicxulub impact, the dinosaurs wouldn’t have gotten out of the way for mammals.” “But dinosaurs were already turning into birds!” You might think that to resolve that argument, we’d need a second Earth and four billion years of research funding. And maybe we would, to resolve it conclusively. But sometimes nature performs a small-scale version of that kind of experiment for us.

The gypsum sand dunes of White Sands, New Mexico. Photo by Fabian A.M.

One such natural experiment is at a special site in the New Mexico desert, a patch of gypsum sand dunes called White Sands. As my University of Idaho colleagues Erica Bree Rosenblum and Luke Harmon show in a paper just released online ahead of print by the journal Evolution, three species of lizards that colonized White Sands are following the same evolutionary path, but in different ways and at different paces [$a]. In the words of a Thai expression Rosenblum and Harmon choose to describe their thesis, the three lizards are “same same but different.”

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Happy Darwin Day!

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The co-discoverer of natural selection and author of The Origin of Species was born 202 years ago today. Nerdy festivities are in the offing everywhere, even Moscow, Idaho.

To assist in your festivities, allow me to suggest my postings for Darwin’s 200th (I’m not so down with the Christianity these days, but I still stand by the points made) and the New York Times‘s great annotated copy of the Origin. You could also check out this interview with evolutionary biologist David Rezick, who has written his own annotated version of The Origin.

Charles Darwin, born 12 February, 1809. Image via Pharyngula.

Is dilution the solution to information pollution?

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ResearchBlogging.orgChris Smith, my good friend and longtime collaborator on all things relating to Joshua trees, pulled into the gas station well after dark. He was on his way back to our field site in the Nevada desert, and this was the last stop before cell phone signals disappeared for good and you had watch the highway ahead for free-range cattle.

It was also the last stop for fresh water, gasoline, and propane. Chris fueled up the van, then went inside for help refilling the spare propane tank. The unshaven, sun-darkened night clerk gave Chris’s flip-flops and tee shirt a sidelong look—they might’ve been perfect back in Vegas around midday, but now it was a freezing high desert night. Clearly unpleased to have to go outside himself, the clerk zipped up his parka and followed Chris out to fill up the tank.

Why do scorpions fluoresce under UV light, anyway? Photo by Furryscaly.

Refilling the propane tank entailed much adjusting of valves and connecting of pipes, which the clerk accomplished with a large wrench. Somewhere a valve misconnected to a pipe, and Chris’s jeans were suddenly soaked in liquid propane. The clerk swore elaborately at the valve, blamed the lazy bastards on the day shift, and took out his frustration on the propane tank with the wrench.

When this miraculously failed to engulf the two of them in fiery death, the clerk straightened out the connection and started filling the spare tank, then turned to Chris and said, “So what’re you doing out here, anyway?”

Evolutionary biologists learn to be vague about their profession in rural areas, so Chris said he was a biologist. No, he wasn’t working for the Air Force base over at Groom Lake. He was studying Joshua trees.

“You must know something about evolution, right?” said the clerk. “I’ve got a question for you.”

Oh, brother, thought Chris. Here we go. How long till this tank fills up?

“You know how scorpions glow under ultraviolet light,” they clerk asked.

Why yes, I do, said Chris.

“How come? I mean, what possible adaptive value does that have?”

Well, you know, said Chris, I don’t have any idea.

“I hear,” said the clerk, “that fossil scorpions millions of years old will glow if you shine a UV light on them. That’s pretty wild, isn’t it?”

You’re right, said Chris. That’s pretty wild.

Chris told this story to everyone else in the field team as soon as he got back to camp, and I think it’s a great illustration of two points that inform the way I think about science blogging. First, that scientists are maybe a bit quick to assume hostility in their audience; and second, that telling cool stories about the natural world is at least as important as confronting the hostility really is out there.

I’ve been thinking about these points ever since ScienceOnline 2011, which I finished with the “Defending Science Online” session, a discussion of strategies for countering all manner of anti-scientific bunk: climate change denialism, opposition to vaccination, creationism, homeopathy. The panelists discussed specific events and general strategies, but they really only discussed confrontation. I left with the nagging feeling that identifying and refuting non-science, however well it’s done, isn’t enough.

Scientific misinformation needs to be contained, but it also needs to be diluted. Photo by kk+.

The trouble with refutation is that once creationists or anti-vaxxers piss in the information pool, it’s nearly impossible to clean up the water. A widely-cited recent study of fact-checking in news articles has shown that corrections often fail to reach people who don’t want to hear them—and the act of correcting a misperception can actually reinforce it [PDF]. Other works shows that even when you convince people that the information they cite in support of political positions is wrong, they hold on to those positions [PDF].

When real-world pollution can’t be extracted from the environment, there’s one final line of attack: dilute it. In the sense that what we call pollution is often a dangerous artificial concentration of some substance that is non-dangerous at much lower, natural levels—carbon dioxide, for instance—the solution to pollution is, indeed, dilution. In the case of information pollution, which we can’t really prevent or contain, we can dilute non-science with, yes, science.

In other words, the best weapon against denialism may not be explicit takedowns of denialism, but good, clear, accessible discussion of science and all the ways it’s awesome. I can speak to this from my own experience growing up in a neutral-on-evolution household in the midst of quite a lot of creationists. I can’t recall that I ever decided evolution was a historical fact because of something I read against creationism. Instead, I came to accept the fact of evolution because I read and watched and listened to a lot of popular science—National Geographic, Ranger Rick, and Nature on PBS—that just took evolution as a given, and showed how it explained the world.

So, while folks like PZ Meyers, NCSE, and Ben Goldacre fight the good fight, I think we shouldn’t forget the value of celebrating science without making it a confrontation. And in the era of Science Online, we’re surrounded by people pointing out things as cool as glow-in-the-dark scorpions. See Scicurious’s Friday Weird science posts, Carl Zimmer’s tale of Vladimir Nabokov’s contributions to entomology, Olivia Judson explaining brood parasitism, or Radiolab’s mind-blowing meditation on stochasticity for just a few great examples selected off the top of my head.

This kind of science communication focuses on the grandeur and fun of the scientific view of life, and it wins supporters to science one story at a time. That’s not necessarily the most exciting part of the struggle against ignorance and denialism. But every time we get someone to say, “That’s pretty wild,” we’re making progress.

References

Bullock, J. (2006). Partisanship and the enduring effects of false political information. Presented at the annual meeting of the Midwest Political Science Association. PDF.

Nyhan, B., & Reifler, J. (2010). When corrections fail: The persistence of political misperceptions. Political Behavior, 32 (2), 303-30 DOI: 10.1007/s11109-010-9112-2

Carnival of Evolution No. 32

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Correction, 11:25h: I’ve just been informed that the fish in the photograph below are not swordtails, but guppies. Burned again by Flickr taxonomy! The real Darwin would’ve got it right, I’m sure.

The Carnival of Evolution is a monthly collection of online writing about evolutionary biology and its cultural and political implications, hosted by a different blogger every month. Today, Denim and Tweed hosts CoE for the first time. Since Charles Darwin’s birthday is this month (only 12 shopping days left!), I thought it might be appropriate to imagine what Darwin himself might have to say about this month’s posts. Share and enjoy!

Photo via WikiMedia Commons.

Down. Bromley. Kent.
Febr. 1, 2011

My dear Hooker,

I was grateful for your very kind wishes; and for the book about the Anoles of the West Indes, which I expect I shall read with much enjoyment. The merest thought of an approaching 202nd birthday makes me feel the need for another trip to Malvern; but I do find some relief in my reading, of which I must needs do more every day it seems, only to keep abreast of the latest work. My great-grandson presented me last month with an i-Pad, a charming device; I can now consult the “web-logs” in the garden, when it is pleasant.

And there is such a lot of reading to do! It seems I read constantly about work extending the ideas I first proposed more than 150 years ago; it is gratifying, and rather humbling, to see what has grown from my little “abstract.” And dear old Wallace’s, of course. (Have you heard from Wallace recently? The last I knew of him, he was departing on that expedition with Greenpeace; but that was more than a year ago.)

Once I suspected my thoughts upon the origins of species would soon be only of interest to students of history and philosophy, but every-where I look I find someone else building upon my ideas.

For instance, experimentation has recently shown that more diverse communities of microbes use resources with greater efficiency, which extends my own simple trials with grasses on a small plot of ground. I am quite interested in the ongoing study of such interactions between species; there has been much interesting work on the co-evolution of hosts and their beneficial symbiotes, in which it is debated whether hosts may control their symbiotes without the need of punishments. And I recently saw that some species of citrus can attract parasitic worms to drive off weevil larvae.

I was also charmed to discover that butterflies of the species Eurybia lycisca, have evolved elaborately long tongues, long enough to take nectar without pollinizing; an unfortunate development for the flowers they visit! And I have recently seen a delightful study of the leaping of Blenniid fishes, supported by many moving pictures; and the very interesting findings of separated forms of the Clouded Leopard in Borneo and Sumatra.

(Here is a charming moving picture of the Clouded Leopard. What a blessing You-Tube is for the stay-at-home naturalist!)

Which is not to say that I think all developments from my theories are sound; you may have read about the idea that women’s tears are modified to save them from molestation, which seems to me curious indeed. I have also seen some very odd speculations upon the morphology of human beings in the distant future. I do not understand why the form should be arboreal. It may be worth recalling, in this context, that Humankind is only one twig in the evolutionary tree of the Apes.

Still more interesting to me is discovering the ways in which I was mistaken (embarrassing as they often are) and facts I was unable to percieve at the time of first writing. For instance, this extensive essay about Mosaic Evolution, or what I might call the Independent Modification of Parts; which evidently has its roots in Lamarckism. We may have been too harsh on the good Chevalier. Equally as interesting is this disquisition upon conditions in which Natural Selection may not lead to modification of descendants. Of course a lack of adaptation might be just as informative as the process of adaptative modification itself!

Of course the experiments of Gregor Mendel were an important improvement to what little understanding I mustered in The Origin; some suggest that now that Mendel’s thinking is over-simple, but it retains much power I feel. The study of living species is so very complicated! We must keep watch not only upon D.N.A. but the myriad complications of its translation to form the structures of the body, and even the duplication of genic code to originate new structures. The greater understanding we have gained since I first concieved of Natural Selection promises to continue improving the condition of humanity; I read, for example, that we may manipulate adaptations lengthen life at a cost to fecundity in order to breed more productive crops.

I must admit that I badly underestimated the role of chance and mutation in the descent of species; especially the degree to which it could allow imperfection to persist, even costly mis-folding of protein molecules. And yet chance changes may have profound consequences for the future of a species, much as my lucky chance to join the crew of the Beagle started me as a naturalist.


A pair of sword-tails guppies. Photo by Alice Chaos.

I have read recently also of several challenges to my original thoughts on Selection in Relation to Sex; experimentation has found, for example that the sexual ornaments of Xiphophorus sword-tailed fishes, do not hamper the males’ abilities to escape danger, which suggests they carry no great cost.

And of course it seems that there have always been persons who object to the idea that we might share kinship with apes and even sessile cirripedes; but fortuitously they seem not to have come up with any particularly novel arguments since 1859. And we may even use Natural Selection to explain the religions that deny the common descent; I suspect that social influences are greatly to blame.

With learned discussion so abundant and easy to find, it is truly a wonder that ignorance and misinformation persist; if only more people did their researches with proper care!

Yours very sincerely,

Thanks to everyone who contributed to this month’s Carnival! Want to submit posts for next month? Go to the BlogCarnivals form, or check out the list of past and future hosts at the carnival index page. Just as importantly, the Carnival needs hosts starting next month! If you’d like to host the Carnival, CoE overlord Bjørn Østman wants you to e-mail him right now.

Carnival of Evolution—just four days left to submit!

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Photo by zen.

The 32nd edition of the Carnival of Evolution will be hosted right here at Denim and Tweed on the first of February! So send me your evolutionary posts by midnight Monday—use the CoE blog carnival form, or e-mail links to denimandtweed AT gmail DOT com.

(Thanks to everyone who’s submitted so far. Looks like it’ll be a good carnival—so all the more reason to submit if you haven’t yet!)

Carnival of Evolution—one week left to submit!

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Photo by k.tommy.

The 32nd edition of the Carnival of Evolution will be hosted right here at Denim and Tweed on the first of February! So you have until midnight, 31 January to send me your posts about evolution and all the grandeur in the evolutionary view of life. Use the CoE blog carnival form, or e-mail links to denimandtweed AT gmail DOT com.

Evolution’s Rainbow, from sparrows’ stripes to lizard lesbianism

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This post was chosen as an Editor's Selection for ResearchBlogging.orgEvolutionary biology is not just the study of how living things change over time, but the study of how the diversity of living things changes over time. Diversity is the raw material sculpted by natural selection, carved into more-or-less discrete chunks by speciation, and lost forever in extinction.

Joan Roughgarden is even more preoccupied with diversity than most evolutionary biologists. Some of her earliest published studies examine the evolution of optimum niche width, the range of resources a species uses, using mathematical modeling [$a] and empirical studies of resource and habitat use in Anolis lizards [$a]. Roughgarden didn’t treat a species as a uniform group, but a collection of individuals all making a living in slightly different ways. Among other subjects, her work informed thinking about ecological release, the changes that reshape populations freed from predators or competitors.

White-throated sparrows are just one species with more than two gender roles. (Flickr: hjhipster)

This interest in the evolutionary context of diversity would eventually become much more personal. In 1998, she came out as transgendered, taking the name Joan after decades spent establishing her scientific reputation under the name she was given at birth, Jonathan. In addition to the challenges inherent to gender transition, Roughgarden’s expertise intersects with her identity in one awkward question: in a biological world shaped by natural selection, how can we explain the evolution of lesbians, gay men, and transgendered people—individuals who are not interested in sexual activity that passes on their genes?

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Carnival of Evolution—two weeks left to submit!

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Photo by mrjojo.

The 32nd edition of the Carnival of Evolution will be hosted right here at Denim and Tweed on the first of February! So you have until midnight, 31 January to submit your posts about evolutionary biology and all its myriad cultural, political, and historical ramifications on the CoE blog carnival form, or e-mail links to denimandtweed AT gmail DOT com.

Carnival of Evolution No. 31

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Photo by kelseyxsunshine.

The 31st edition of the Carnival of Evolution is online at The Dispersal of Darwin—it went up at midnight, New Year’s Day, if I’m not mistaken. In spite of the holiday season, the post list is pretty overwhelming—contributions include Jerry Coyne on reinforcement, John Hawks on the new proto-human genome, Brian Switek on fossils that contributed to evolutionary theory, and Krystal D’Costa on the evolution of gestures for communication.

Check’em out, and tune in next month, when CoE number 32 will be hosted … right here! Submit your posts about evolutionary biology and all its myriad cultural and historical ramifications on the CoE blog carnival form, or e-mail links to denimandtweed AT gmail DOT com.