"Only an arc looking backward": Trevor Price and Dolph Schluter reflect on formative years atMichigan

Drs. Trevor Price (PhD '84) and Dolph Schluter (PhD '83) met as PhD students in Ecology and Evolutionary Biology at the University of Michigan in the fall of 1977, when they arrived as new students of renowned evolutionary biologist Peter Grant. They conducted pioneering work on adaptive landscapes and rapid evolution in Darwin’s finches as PhD students, and have remained friends ever since, even as they have gone on to their own distinguished careers.

Price is now a Professor of Ecology and Evolutionary Biology at the University of Chicago, and Schluter is the University Killam Professor of Zoology at the University of British Columbia. Each has made important and enduring contributions to work on speciation, biogeography, the role ofecology in driving evolution, adaptive radiation, and quantitative genetics, among other topics. Theirfriendship, they agree, has been characterized by the kind of rigorous academic debate that makes eachparticipant a better scholar, because it requires both to form an argument that is worthy of a friend’sscrutiny. In the following interview—conducted by EEB PhD students Matt Hack and Max Witynski and EEB Associate Professor and UMMZ Curator of Birds, Ben Winger—the two reflect on their formative experiences at Michigan, how their PhD work influenced their later careers, and the ways in which thefield has changed since their time in Ann Arbor in the late 1970s and early 1980s. 

Q: What brought you to Michigan?

Trevor: I was taking two years off, and before a year working in India, I saw an ad for a position with Peter Grant—who was at McGill University at the time—to work in the Galápagos Islands. It sounded like a good gig to spend the summer in Montreal, and the winter in the Galápagos! I was interested in population genetics and was blown away by the work Peter Grant and his graduate student Peter Boaghad already started: color-banding individuals, measuring trait differences between them, following them, and ultimately measuring heritability in the field for the first time. So, I was excited to be involved in that work from the beginning.

Dolph: I didn’t have much of a background in evolution, more in ecology. I was interested in competitive exclusion and the structure and assembly of communities. I wasn’t even planning to go to graduate school, until Bob Montgomerie, one of Peter Grant’s students (and now Emeritus Professor of Biology at Queen’s University), came to my university and gave a talk on territorial behavior in hummingbirds. The talk blew me away, with its implications that you could study evolution in the field, so I applied! But Peter wrote to us that summer and told us he was moving, and that we had the option of joining the cohort at Michigan instead of McGill. My undergrad advisor told me it was a good school, so I went!I was working at Algonquin Park as a field assistant that summer, and I remember leafing through issues of Ecology. I pulled one out and read this paper by a grad student at the University of Michigan named David Tilman (BS ’71, PhD ’76, now Regents Professor of Ecology, Evolution, and Behavior at the University of Minnesota). The paper was well written, conceptually interesting, and a neat experiment—just so good! It intimidated me, but it made me prepare for what was coming. I had never been farther south than Boston, and suddenly I was headed to the Galápagos!

Q: What was it like working with Peter and Rosemary Grant?

Trevor: They’re English and I’m English, so we could talk about cricket, etc. We also liked to argue about topics in ecology and evolutionary biology: I remember arguing with Peter in the field about things like whether owls reduced the finch population below carrying capacity, allowing more species to coexist.

Dolph: Peter was good at listening to us even when we disagreed with him and with each other. He wasa good advisor that way; he was upbeat, and he listened. I remember learning to capture and measure birds from Peter. But I also remember that we had to think on the fly about how to get our projects started, and they were eager to help. I collected tin can lids and painted them, and the Grants helped meset them out every kilometer along an altitudinal transect to designate our first study sites. Even though I hardly knew what I was doing during those first weeks, they were energetic. As soon as we finished onething, they’d ask, “What’s next?”

Q: Are there any differences between the popular understanding of Darwin’s finches—the story about adaptation during drought years—and your more comprehensive experience of that work?

Trevor: Some technical details about beak evolution may have been lost—for example how selection on width differs from depth—but I think the most exciting developments that have been overlooked have been recent ones in the last decade that have linked the selection events that we observed in the past to actual underlying loci.

Dolph: I think the adaptive landscape aspect of the finch work was written up well by Jonathan Weiner in The Beak of the Finch, and I’m glad that the rapid evolution aspect of it has captured the public’s interest. But I think the enduring value for evolutionary biologists is that it changed the way we think about evolution and how we conduct science in important ways.

Q: What was it like being a student in this department during your PhDs?

Dolph: I remember Friday afternoon happy hour discussion groups. The topics that were discussed therewere often completely unknown to us or over our heads, but they were really influential for me. Just to hear the senior graduate students argue some of these questions and raise topics was amazing. I think it’sa key thing early on and a necessary part of grad school.

Trevor: Michigan was and remains just an incredible collection of people. The two offices opposite mewere occupied by Marlene Zuk (PhD ’86, now Regents Professor of Ecology, Evolution, and Behaviorat the University of Minnesota) and David Queller (PhD ’82, now Spencer T. Olin Professor of Biologyat Washington University in St. Louis), and I shared offices with Dolph, and all three of those friends of mine are now in the National Academy of Sciences.

Dolph: Not only was it an amazing group of brilliant people, but it was very interactive. Everybody worked really hard, but everybody also played really hard. There was a lot of energy in all directions. It was such a fun time to be there, and truly, I remember my first year of graduate school as one of the best years of my life. It was hard, but it was amazing.

Q: Tell us more about how you influenced each other, and brought that collaboration forward after Michigan.

Trevor: In addition to sharing an office, we were also roommates.

Dolph: Our musical tastes did not align!

Trevor: But more seriously—we experienced a lot of personal development together, too. We were competitive, and we argued—

Dolph: But I think it wasn’t really about besting each other. It was about getting things right so that when I argued with Trevor, I would really know what I was talking about!

Trevor: Afterwards, I always had the ambition of having a lab where friends could argue in that way. Idon’t know if I’ve really succeeded. It wasn't competitive in that sense, you're right. It was more like trying to keep up with the other person. You know, since then, we’ve converged in some ways. Dolph started off with species’ distributions and went into genetics. I started off in genetics and then went into distributions in a big way. Because we were so close, there were things we could discuss about our respective papers that it would have taken other people ages to catch up on. If I had a project that I couldn’t do on my own, I’d recruit Dolph to help me.

Dolph: My adaptive radiation book would have gotten nowhere if I hadn’t been able to rely on Trevor’s input. Now that I’m working on sticklebacks, there’s a lot of evolutionary genetics in there. When I was a student, I tried to read a paper a day. Trevor introduced me to Lande (1979), which was a paper that I read over and over for several days, until I really understood it and realized just how profound it was, even beyond its utility for measuring selection on correlated characters, but for modeling the evolutionary process and its macroevolutionary significance as well.

Q: You’ve emphasized the importance of reading seminal papers. Do you think the literature has gotten too voluminous? Is it possible for students to read deeply in the same way and stay on top of things now, as it was then?

Trevor: To be fair, Peter told Dolph and I that the literature was already too enormous in the 1980s and joked that he couldn’t have done a PhD then! There have always been more papers than one can read. I would advise students to pick a few papers by the top people in your subfield and read them thoroughly. Also, even though the literature has grown, in some ways it’s also easier to find papers than ever. You don’t have to go to the library and physically track them down. Leigh Van Valen used to run a class here at the University of Chicago in which people would read old papers. It doesn’t happen much anymore—but Lande 1979 is still worth reading!

Dolph: I try to advise my students to read the naturalists, such as the works by David Lack. But I find that students don’t read as much theory as we used to, partly because they devote so much time to learning modern techniques, such as lab work, coding and bioinformatics, and it's a full-time job to do that. I find myself marveling at the number of R packages used in a methods section these days. So, who has time to read the general papers, the papers with ideas? I talked to (Stanford biologist) David Kingsley about this recently, and he said that he tells all of his students to read papers that describe whole genomes, like the coelacanth genome paper. He considers those papers to be a new kind of natural history: They’re big, monstrous papers that pull together a lot of ideas along with modern methodology. So, I think what you have to do is learn to keep your eye out for a certain kind of paper that zooms back out to the big picture. Also, it’s always worth saying: If you notice a pattern during your fieldwork, look it up! You may find that no one has written about it yet, and you’ll be the first.

Q: You’ve both developed remarkable long-term study systems—Himalayan birds and sticklebacksin Canadian lakes. What led to that depth of involvement with those systems, and what’s beenrewarding about working in them for so long?

Dolph: I have three big reasons for working on sticklebacks. First: I wanted to find a system where I could test theories with experiments; to ask and answer questions like, ‘How is natural selection on a species changed when a competing species is present in its environment?’ It was the end of the Cold War, and I fancifully entertained the idea of acquiring a series of aircraft carriers and creating an archipelago of ships covered with dirt and seeding them with Galápagos finches, singly and together. But then I learned about this stickleback system from a graduate student here at UBC. The benthic-limnetic species pairs are similar to what we saw in the finches and other low-diversity systems wherey ou have repeatability due to the presence of islands (or lakes). The second reason was that I got interested in the origin of species. It started on the Galápagos with the idea that a species might originate more than once by processes like those which cause beak size to be modified. I noticed a similar pattern in sticklebacks, in which we found incredibly young, largely but not entirely reproductively isolated, and ecologically highly differentiated species in sympatric environments. So my question was, is this coincidence, or is it possible that ecological differences have something to do with the origin of species? The third reason was that genetic work, initiated by David Kingsley and (University of Bernevolutionary ecologist) Katie Peichel—and (Georgia Tech biologist) Greg Gibson, who was at Michigan at the time—helped overcome what I regarded as one of the main limitations of the stickleback system, which is indeterminate growth. Fish are hard to measure and track, but if you can find an allele that you can genotype that's strongly associated with a phenotypic character, then you can suddenly start to measure selection over the lifespan and look at evolutionary change. So, it was a good system for my initial goals, and it just keeps on giving.

Trevor: The Himalayas are incredibly biodiverse, but understudied. When I first went there in the mid-1970s, I was motivated by David Lack’s argument that nobody had ever studied MacArthur’s warblers in the winter. So, I wrote a grant to study warblers in the winter; just the warblers that I’d grown up within England. In some ways, the rest is history, because once you start studying them, ten more questions come up, and by the time you’ve answered those, you want to get back to the Himalayas as soon as youcan.

Q: What exciting questions remain unanswered?

Trevor: One of the huge mysteries that we’re nowhere close to solving is why birds and other animals are the colors that they are. I'd like to one day write a review paper on the ways you can go about studying that, but I'm really keen on using what we know about the evolution of bird color vision to investigate that. But the other area, of course, is anthropogenic influences on populations. When you get to be our age, you get more and more concerned about conservation. I’d like to see us do more science that addresses conservation issues. One way forward I see is greater collaboration across disciplines, including economics.

Dolph: A big technological improvement that I’ve been waiting for is the ability to follow individual sticklebacks, but that's still far in the future. Now, I’m interested in tracking how evolution occurs rapidly as a consequence of a large pool of available variation. I would love to have complete genomesequences of every population in the world, so that we could track how alleles become adaptive when a group of individuals colonizes a new environment. Essentially, the processes by which variation is acted upon by natural selection, and how it got there in the first place. I think we're almost capable of doing that. From a conservation perspective, one of the things I'm interested in is collapse. Species go extinct for avariety of reasons, but one of the ways that young species go extinct is through hybridization that leads to collapse. It might be happening in the species that Trevor and the Grants studied on Daphne Major (Geospiza scandens and G. fortis), which seem to be hybridizing more, and are converging in at least some traits. This raises some interesting questions for me about how they ever managed to persist in the first place. This is a macroevolutionary question, because to get biodiversity you have to get from one species to two sympatric species, and to three and four.

Q: What are some of the biggest changes in ecology and evolutionary biology that you’veobserved?

Trevor: The first category is methodological, particularly in molecular biology and computation. Theworld is completely different now with regard to both. I remember when people would do principal component analyses just to reduce the physical size of their data, in terms of cards fed into a machine! We're seeing another revolution right now with AI, which is just amazing. Globalization is another big change. But the other thing that I would point to is the deterioration of ecosystems: Birds have declineds o much, especially in the last 25 years. It’s really getting noticeable, and it’s a crisis that we're all living through now.

Dolph: Working in the Galápagos in the late 1970s, my field assistant and I wouldn’t see anyone else for weeks. One day an aircraft carrier went by. We had no idea if a war had broken out. We were taking a level of risk and experiencing a level of isolation which is hard to comprehend nowadays. Also—weknow now that climate change was beginning, even then—but we had a feeling at the time that we were studying organisms in the environments in which they had evolved. That is no longer possible. As evolutionary biologists, that is one of our greatest losses.

Q: What about the trajectory of your careers would surprise your graduate school selves?

Trevor: I still can’t believe that I’m being paid to do this. My ambition has been to study Phylloscopus warblers since I was about 10 years old. The surprising thing, to me, is really that the dream has been fulfilled, in many ways.

Dolph: I told you already that I ended up at Michigan almost by accident. It took me a few years to realize that I loved this. I felt like at Michigan—maybe for the first time in my life—that I was among my own people. I can remember during my time in the Galápagos and at Michigan, I felt that intellectually and physically it was the most demanding period of my life, but I enjoyed it all. So, I just thought, well, I'll figure out a way to keep doing this. And so, there's only an arc looking backward, inretrospect, and never forward.