42 Cloudy weather at Eagle Lake
In the spring of 1982 or so, Steve Arnold and I joined Harry Greene and his herpetology class (UC Berkeley) on a desert field trip. Being in the field with these two great naturalists, and accompanied by Harry’s enthusiastic students, was fun.
At one point Steve said he would be heading to Eagle Lake after this field trip. He had been conducting a long-term study of the demography of garter snakes at the Lake. We had done the ‘hot-rocks’ project at that site (Chapter 41), and Steve asked if I wanted to join him. Of course!
The weather was overcast and cold throughout our stay at Eagle Lake, and we never bothered to look for g-snakes. Instead, we sat around campfire, cooked quesadillas, and drank wine (not full- time!). And we talked.
Steve had just drafted a paper (“Morphology, performance, fitness”) that was later published in 1983. In that paper Steve developed a path diagram and some equations to how various morphological traits (leg length, body length) could directly and interactively influence “performance” (speed, stamina), and how in turn those performance traits could directly and indirectly fitness. He told me about work he’d done with Al Bennett, measuring individual variation in speed and stamina of garter snakes. The next logical step would be to measure morphology, speed, and stamina of snakes, release them back to the field, and monitor survivorship measured individuals. I was not an evolutionary biologist at that time but was spellbound by Steve’s ideas.
Part of Steve’s concept had been around since 1966, when George Bartholomew eloquently described how different “levels of analysis” (e.g., molecular, tissue, organismal) were functionally linked, and I’d drawn an overly complex diagram in my Biology of the Reptilia chapter in 1982. There, and also in Huey and Stevenson, 1979, I had argued that whole-animal performance traits were more ecologically relevant than were lower-level traits (e.g., twitch tension of isolated muscles). However, once I saw Steve’s path diagram, I suddenly understood how to link morphology (or physiology(), performance, and fitness. This was the same feeling I had when I first saw figures 5-7 in Joe Felsenstein’s 1985 paper on phylogenies and the comparative method. Both were pinball moments for me, and shifted my research from ecology to evolution.
Steve also introduced me to quantitative genetics, which was needed to link morphology, performance and fitness, and evolutionary change. He had formalized this approach with Russ Lande, a brilliant theoretician. This was all new to me – I was a physiological ecologist, not an evolutionary biologist. But I immediately saw the power and applications of the synthetic approach that Steve and Russ were developing.
I had a sabbatical coming up, and so I decided to spend the fall at the University of Chicago, where Steve and his high-powered colleagues (Russ Lande, Mike Wade) team-taught a ’super” course in evolutionary genetics. I came back the next fall for a replay, and Brian Charlesworth had joined the team. Much of their course was over my head, but I learned enough to understand basic concepts. Steve was (and is) a gifted teacher. He could explain – via words and elegantly simple graphs – complex evolutionary issues.
Talks with Steve around the campfire at Eagle Lake, and my sabbatical autumns in Hyde Park, led me to organize a study of performance and survival of hatching fence lizards (Sceloporus occidentalis). I worked with two of my grad students (Rickie van Berkum and Joyce Tsuji) on a population of these lizards near Bingen, just north of the Columbia River. Joyce and Rickie found a good site, got permission from the landowners, and did a pilot capture-recapture study, which demonstrated that the project was feasible.
The following year we collected 30+ gravid females, took them to our lab in Seattle, where they laid clutches of eggs. We transferred eggs to individual cups (filled with moistened vermiculite) and incubated them for several weeks. Once the lizards hatched, we sexed and measured their dimensions and also measured their sprint speed (in a computerized drag strip) and stamina on a treadmill. Finally, we released over 300 hatchlings back at the field site.
We returned in that fall, recaptured surviving hatchlings, and re-measured and re-raced them. These data enabled us to evaluate whether speed and stamina were repeatable during ontogeny. In other words, did fast hatchlings stay fast later in life? For our hatchlings, the answer was yes. In fact, speed and stamina were more repeatable than relative body size.
We came back the following spring and Ted Garland, Jr., a new postdoc in the lab, joined us for a second recapture. We were devastated to discover that the land owners had cleared the oak trees from one large section of our study plot. They had heard that the government was going to prevent further logging along the Columbia River gorge, and so the landowners logged immediately. Conservation initiatives sometimes backfire. In any case, we captured as many survivors as we could, but our enthusiasm for continuing that project waned.
We did publish a few papers based on that study.