Monday, May 27, 2013

Predictable unpredictability and 25 stickleback biologists in the field.

Ecology and evolutionary biology – and their intersection (evolutionary ecology, eco-evolutionary dynamics) – strive for inferences that are robust, consistent, and stable. For instance, investigators commonly explore how organisms differ between habitats (different “ecotypes”) and how these ecotypes have different ecological effects. Once the differences are discovered and the patterns established, we would expect them to be at least relatively consistent through time: year after year after year low-predation guppies should look like a low-predation guppies and high-predation guppies should look like high-predation guppies. With such consistency, we can draw robust general conclusions about the way the world works. Without such consistency, what do we have beyond a series of snap-shots with little generality to connect them?

Sampling the Misty Inlet Stream.

I spent last week in the field on Vancouver Island helping to start some new projects on the threespine stickleback that live in lake and stream environments. This is a system where the patterns are well established, robust, consistent, and stable. For instance, lake stickleback are always shallower-bodied than are stream stickleback – and surely 15 years of studying the same stickleback populations should allow a researcher to draw many such generalities.  

Dieta shows how it's done.

One of this year’s projects, led by PhD student Dieta Hanson, seeks to understand how differences in breeding time contribute to reproductive isolation (i.e., low gene flow) between adjacent lake and stream populations. In particular, previous observations suggested that stream populations start to breed earlier than adjacent lake populations, which should mean that the two ecotypes will show reduced interbreeding and thus restricted gene flow. With this prior experience as her motivation, Dieta has been repeatedly sampling a variety of lake and stream stickleback populations so as to assess changes through time in the number of reproductive males and females, which will allow her to calculate overlap in breeding time and thus the potential restriction on gene flow. This past week, a group of us joined Dieta to sample the Beaver, Misty, and Robert’s watersheds.

The Misty crew hard at work

I had asserted that stream fish breed earlier than lake fish not only to Dieta but also to everyone else on the crew, including stickleback savants Katie Peichel and Rowan Barrett. Much to my surprise, our Misty Lake sample turned up a fair number of reproductively mature individuals but the Misty Inlet stream sample turned up none – not one gravid female. After having not-so-subtly pitched myself as the resident expert on stickleback, I had to start back-tracking to somehow limit the damage to my reputation caused by this new observation. I think I failed because the crew started poking fun at me (or rather with me) – not just for incorrect stickleback assertions but for my tendency to misplace the truck keys in grocery stores, for my failure to have brought any soap or shampoo or towel, for my affinity for hot chocolate, and so on. However, the next day we sampled the Misty Inlet stream again and found a number of gravid females – so perhaps I rehabilitated my reputation somewhat (at least the stickleback part), especially after winning the pool for predicting how many stickleback we would catch (I was only off by one). Overall, however, it was becoming clear that the dramatic difference in breeding time that I had come to expect might not be strong and consistent.

Rowan and Katie: are they laughing at me or with me?

After working on the Misty and Beaver lake-stream pairs, both located on northern Vancouver Island near Port McNeill, we drove south for a couple of hours to Robert’s Lake Resort near Campbell River. Here we were to continue our lake-stream work, starting with the Robert’s pair, and here we would be joined by our collaborators from the University of Texas at Austin, including team leader Dan Bolnick. On the night that everyone arrived, all of us (one-quarter of a hundred people!) gathered in a room for some discussion, introductions, and a pep talk from Dan. Dan went over safety and security issues, of course, but – more importantly – imparted to us his considerable wisdom regarding the local stickleback populations, especially that in Robert’s Lake itself where he had been working for 13 years. “I have never seen a stickleback breeding in Robert’s Lake before June 6” was the phrase I most remember – perhaps because the next morning I walked down to the dock at the lake and saw two breeding males. One of them had babies already, which meant that it must have started breeding at least a week (and perhaps two) earlier. This means that breeding must have started in Robert’s Lake more than three weeks before the previous earliest date. Now it was Dan’s turn to try to salvage his reputation as the local stickleback guru, and together we converged on the best way to do so – we started trading stories about how unpredictable things could be.

Dan: “It is amazing how some years the stickleback are small and other years they are large.”
Andrew: “Ah, yes indeed Dan, and how in some years they have incredible nuptial color and some years much less so.”
Dan: “Right you are Andrew, and some years they breed early and sometimes late.”

I am sure you can see here how we had cleverly shifted from our earlier statements of confidence in generalities to statements showing our rich knowledge of variation and exceptions, knowledge that could only be achieved through our long and detailed experience in these systems. Next year, and in those that follow, I will start from this new position and thus never be wrong again.

Dan's other project - the search for assortative mating in stickleback.

The entire crew only overlapped at Robert’s Lake for one day but we did have time for a farewell drink of Scotch (we now “own” a one square-foot plot of land at Laphroaig – and it even has a stream flowing through it) over which we could argue on topics from the trivial to the important. And argue we did, well past when we should have been in bed – but it was somehow appropriate as it was under a very similar situation in the same building and over the same beverage that Dan and I first met many years ago. Up to that point, we had both been working on stickleback in the same lakes for a number of years but hadn’t realized it. So we converged on Robert’s Lake in 2006, played a Hendry-lab verus Bolnick-lab Ultimate Game (I can’t remember who won but I do know that we asked for funding for an Ultimate trophy in our NSF grant.), and hatched several collaborations.

Robert's Lake Hendry v Bolnick ultimate tourney, 2006.

Sadly, field work is now over for me and I am writing this post in the Campbell River airport. But I can rest easy knowing that the field work will continue unabated without me, although I am not sure the tarps will be set so elegantly anymore. Matt will still be wading right to the top of his waders – and sometimes fearlessly beyond. Suzanna and Elena will still be tucking their jackets inside their waders and cooking amazing dinners. Katie will still be making hundreds of stickleback babies and organizing data by headlamp while in her sleeping bag. Rowan will still be the red canoe that every photo needs. Dieta will still be two steps ahead of everyone else. And Carol will be there to film it all. And –most importantly – large bags of nuts will still be three for five dollars at Sayward Junction. Have some for me!

Be the red canoe, Rowan.
24 of 25 - with a stand in for Duncan.

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