PITCHFORK SCIENCE: Guppies, Stickleback, and Darwin’s Finches.

[This is a cross-posting with the EXEB blog at Lund - thanks for the reciprocal opportunity Erik. And thanks for your earlier post here on Eco-Evo-Evo-Eco.]

I study Trinidadian guppies, threespine stickleback, and Darwin’s finches, surely 3 of the top 10 evolutionary biology “model” systems - for vertebrates at least. I thus fall at one extreme (or is it three extremes?) on the “pick a model system and use it to answer my question” versus “develop a brand new system all my own” continuum. Many students and postdocs find themselves facing their own decisions about where to position themselves along this continuum. Should they take the shortcut of working with an established system so they don’t have to work out the simple details and can get right to addressing the big general questions? Or should they forge their own path and become an expert in something brand new? It might seem, based on the above listing, that I consciously took the first approach but the reality is something quite different. In truth, I used a “follow your nose” coincidence-and-serendipity approach to study system choice. I here trace my own personal history in these research areas before closing with some general thoughts on how to choose a study system.

Why I study salmon: a 16 year old me with a steelhead from our cabin on the Kispiox River (BC, Canada).

I worked on salmon for my MSc and PhD, largely because I grew up with salmon fishing as my primary passion. Thus, I began studying salmon simply because I liked them and liked fishing for them. This led me to choose an institution (University of Washington - UW), department (School of Fisheries), and supervisor (Tom Quinn) ideally suited to immerse myself in salmon work. As my graduate work progressed, I very gradually became more and more interested in general questions in ecology, largely through exposure to the research of other people in the department. I even started subscribing to Ecology in addition to – of course – Fisheries. Yet my thinking remained salmon-centric: “what can ecology tell me about salmon”? Nothing wrong with that, of course. Then, when visiting home for Christmas in 1994, my mother gave me a book: The Beak of the Finch by Jonathan Weiner. When your Mom gives you a book for Christmas and you then spend the next week at home… well, you better read it.

The laboratory for my PhD: Lake Nerka, Wood River, Alaska.

The book was amazing. It described in wonderfully readable prose the research of Peter and Rosemary Grant on Darwin’s finches in the Galapagos Islands. What struck me the most, while reading beside the heater vent looking out at the blowing snow and -40 C weather (literally!), was Jonathan’s description of how the Grants had documented generation-by-generation rapid evolution of finch beaks in response to natural selection resulting from environmental change. Wow – you can actually study evolution in real time! It was my own eureka moment and, in short order, I became captivated by the idea. As soon as I got back to UW after Christmas, I went to the library and photocopied EVERY paper on Darwin’s finches (ah, libraries and photocopying – the good [and bad] old days). From then on, almost as though my brain had achieved an alternative stable state, my thinking was inverted to become: “What can salmon tell me about evolution?” 

My MSc and PhD work focused on sockeye salmon - this one in Knutson Bay, Lake Iliamna, Alaska.

Salmon did tell me a lot about evolution. I even edited a book (Evolution Illuminated, with one of my evolutionary idols, Steve Stearns) about merging evolutionary theory and salmon research. However, when one starts focusing on a topic (evolution) rather than an organism (salmon), one starts to become irked by aspects of the organisms that are not optimal for addressing the topic. Most notably, it is very hard to do experiments with salmon unless you have lots of water, lots of space, and lots of time. So, when thinking about a postdoc, I started talking to folks about which systems might allow me to better address basic evolutionary questions. I ended up moving in two directions.

The laboratory for my first postdoc. For more than a month of glorious weather, I camped on a small island in a small lake (Mackie Lake) at the end of a 4-wheel drive road. Those are my mesocosms floating in the lake and projecting from the island.

The first was the University of British Columbia (UBC) – because I didn’t want to go too far from my girlfriend (now wife) who was still at UW. I visited UBC and went from prof to prof telling them of my interest in a basic evolutionary question – the balance between divergent selection and gene flow – and asking if they knew of a system that would be good for testing my ideas. Many great suggestions were made, but Rick Taylor insisted he had the perfect system: Misty lake-stream stickleback – and he was right. So I started working on stickleback not because they were a model system, but because someone suggested they would be well-suited for my question and because it let me stay reasonably near my sweetheart.

A threespine stickleback guarding his nest.

The second direction came about through a conversation with Ian Fleming, who suggested that I should work with David Reznick on guppies. I hadn’t even considered this possibility, but I knew a bit about the system (which is also described in The Beak of the Finch) and it seemed cool. So I went to UCR and met with David and talked about how we might use guppies to study the interaction between selection and gene flow. David said he would be happy to help me with this work but that he didn’t have any money for me – and so I offered to write a full NSF proposal. I was just gearing up to do so when I heard that I had received an NSERC (Canada) postdoctoral fellowship to work with Rick Taylor on the Misty system – so off I went to stickleback, leaving guppies behind.

My favorite wild guppies captured in my first year of sampling, 2002.

UBC was great, an outstanding place for nurturing interest and insight into general questions in evolutionary biology, but one must eventually move on. My next postdoc was the Darwin Fellowship (I applied because of the title) at the University of Massachusetts (UMASS) Amherst, working with Ben Letcher on salmon again (hard to shake the habitat). While at UMASS, my guilt started building about telling David I would write an NSF grant and then not having done so, so I went ahead and wrote one, which got funded on the second shot (after bringing in my salmony lab-mate from Tom’s lab, Mike Kinnison). So my work on guppies eventually developed owing to guilt about not carrying through on something I said I would do.

The laboratory for our guppy work - here the Paria River, Trinidad

While at UMASS, my office happened to be near that of Jeff Podos, who was working on Darwin’s finches. Near the end of my Darwin Fellowship, Jeff received an NSF Career grant and had money to burn – I mean invest. Jeff knew of my interests and asked if I wanted to come along to the Galapagos on the project (he recalls me asking – or perhaps begging – to come with him), and of course I immediately said yes. So my work on finches was simply a case of being in the right place at the right time. The experience was every bit as exciting as promised in my day dreams that cold winter back in 1994. Several years later, Jonathan Weiner called to talk about my salmon work and I was able to tell him how influential his book had been and how it actually brought me (without any plan) to work on finches.

The laboratory for our finch work, presided over by a marine iguana.

In short, a large amount of coincidence and serendipity determined my choice of study systems. Once in each of the three systems, I became enamored with them and never left. I have now 25 papers on stickleback, 22 papers on guppies, and 11 papers on finches, and I have no intention of ever pulling back from any of these systems. I have also published 33 papers on salmon, and I continually look for new opportunities for additional work on them.

Perhaps my favorite finch photo.

Peter Grant once told me that, in conversation with Daniel Pauly at UBC, Dan told him that he (Peter) was a “point person” whereas he (Daniel) was a “line person”: a point person being someone who takes a single subject/system (finches) and looks at every aspect of their ecology and evolution, and a line person being some who takes a single subject (fisheries) and looks at it across many systems. I guess that makes me a pitch-fork person – trying to go into depth in three systems. Of course, this means that I can’t get too deep in any one system, much to my frustration. However, comparing and contrasting results from the three systems has proved fascinating. For instance, I study ecological speciation in all three systems with essentially the same methods (catching, banding/marking, measuring, recapturing, genotyping) focused on revealing the same processes (disruptive/divergent selection, adaptive divergence, assortative mating, gene flow). The similarities and differences in results obtained from the three systems has proved very instructive and motivational. In fact, my favorite research talk involves walking through a comparative story of ecological speciation in the three systems.

The title slide of my pitchfork talk.

Beyond how many systems one works in, I need to return to the question of working with model (developed) versus new (undeveloped) systems. As noted earlier, a benefit of working in a model system is that one doesn’t have to do as much background work (although every system is nowhere near as well-understood as the impression given by the literature), whereas a cost is that you are never known as the expert in that system (because the experts are the senior folks working on the same thing). The cost-benefit payoff is not easy to calculate and so the temptation for many students and postdocs is to spend a lot of time debating the pros and cons of the different approaches. I think all this angst is a mistake (or at least suboptimal) and that one should instead follow one’s nose (and Mom’s book recommendations). I think everyone should work on the systems and with the people that they find the most interesting and inspiring – not the systems that have the best-described genomes (as an example). These inspiring systems might be model systems or they might be new systems or both (I also have students who work on non-model systems), but they are – most importantly – the systems that feel right at the time, not the systems that have been rationalized based on a logical calculation of optimal career advancement. It worked out fine for me (and many others) – although I am sure my colleagues would argue I could still use considerably more career advancement.

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Resources:

An interesting perspective by Joe Travis on question-based versus system-based science: Is it what we know or who we know? Choice of organism and robustness of inference in ecology and evolutionary biology