Ryan Calsbeek is a professor in the department of biological sciences. He specializes in natural selection and studies evolution in reptiles and amphibians. Professor Calsbeek is teaching Biology 27, “Animal Behavior,” this fall.
In brief, what topics do you research?
RC: My work primarily focuses on how natural and sexual selection operate in the wild. So I study reptiles and amphibians, and I use those animal systems as models to ask questions like, “Why do some individuals live while others die?” and “What are the traits that influence the probability of survival or the probability that an individual reproduces or not?”
What got you interested in those topics?
RC: My undergraduate study began as an English major, then I transitioned to philosophy. Then, listening to the echoes of my parents in the back of my head saying, “We’d love to have a doctor in the family,” I began to study biology with the idea of going to medical school. Toward the end of my junior year in college, I met a professor out on a bike ride, of all places. We started talking, and he invited me to go and do research in his lab, thinking that it might help me make it into medical school. That research project involved doing hormone manipulations with lizards. This eventually led to a research position with him in the field. I went to California and did field work, and after one season doing field biology I was totally hooked. That sent me on the path that I ended up on, which was to become an evolutionary biologist doing field work.
How does one study evolution within a species?
RC: Usually, measuring variation and survival requires being able to track the survival of individuals over the course of their entire life. For the system that I work in, those animals mature and die in a single year. In the early part of the breeding season, my work involves marking and measuring large numbers of individuals in a population and then following them over the course of their one-year lifespan. At the end of the year, we census populations to see who’s still alive. Those individuals who are missing from the population are assumed to be dead. Then, because we’ve measured traits of the animals, like their leg length or running speed, we can build correlations between who lived and who died and the traits that may have influenced their probability of survival.
What places and environments have you studied for your field work?
RC: I started my Ph.D. work in the Central Valley in California, I worked in the Diablo Range and also I’ve been to Sierra Nevada. Then I worked on islands in the Bahamas for about the last decade or so. And more recently, I’ve started studying wood frog populations that live in ponds locally around here in Hanover and Norwich.
What drew you to studying animals like lizards and frogs?
RC: Initially, the draw was my early experience with them. It was all that I really knew. As time went by, I realized that [studying] a small animal that is extremely common, can be captured relatively easily and matures and dies in a short period of time makes studying natural selection a lot easier than, for example, an animal like a bird. A bird is very hard to recapture because they fly away and they live multiple years, so a study takes five to ten years instead of one or two years. The things that make a good study system for measuring selection are [animals] that live a relatively short amount of time, are relatively abundant, are easy to catch and are easy to measure.
What are some of the big questions in evolutionary science?
RC: “Evolutionary science” is a broad term. Essentially, everybody who does real biological science is studying evolution in some way. A cellular biologist is studying evolutionary processes, and the questions that they want to answer are different from the types of evolutionary processes that an organismal biologist would be studying. We’re all trying to understand the processes that shape and maintain biological diversity. At its core, evolution is interested in the study of diversity, both in its underlying mechanisms — the genetic and selective mechanisms that generate that diversity — and the cellular processes like mutation that provide the raw material for building diversity ... The question that we’re trying to answer now is how natural selection gets around the conundrum where you have to use a single genome to build two dramatically different things, like a male and a female. Or in the case of the wood frogs that I study, things that are even more dramatically different, like a tadpole and an adult frog, which have to be built from the very same genome as one individual. We call these “genomic conflicts.”
What do you like about the department of biological sciences and Dartmouth as a whole?
RC: One of the best things about the department at Dartmouth is that it’s a relatively small program, much like the entire campus. The small size allows us all to integrate undergraduates into our research program along with graduate students and postdoctoral students. It gives me the freedom to include my own work and my own research in the topics that I teach, and it allows me to take the material that I teach with undergraduates and use that to build on my research program. The number of times that my own research has been influenced by questions that have been raised by undergraduates or by early graduate students in my lab, just due to the quality of the academic community here, surprises me again and again. Another great aspect of Dartmouth is that its small size facilitates relationships between different departments. I have collaborations that span the campus. One of my main collaborations outside of the biology department is with a professor at the Tuck School of Business, if you can believe that. These are the types of opportunities that don’t arise on a huge campus. My undergraduate education was at Indiana University. There were 60,000 students on that campus, and most of those people were completely anonymous to me my entire time there. But here, relationships build almost spontaneously. I drop my kids off at school and I meet another Dartmouth professor in some other department and we start talking and find we have common interests. That’s a huge benefit to being here.
What can students get out of a biology course, especially one that teaches about evolution?
RC: I think most students initially view the natural sciences, including biology, with a long view of eventually going to medical school or to graduate school. But there is so much about today’s world that the safety of our future depends on people having some perspective from ecology and evolutionary biology. We think about the problems of climate change and of sustainability on a planet that’s reaching its carrying capacity in terms of the number of people on it. And our future leaders, whether they’re scientists or politicians or teachers or anything else, will serve their communities to a much greater extent if they have at least some understanding of the ecology or the evolution that’s going on around them. It will help them inform decisions politically or the things that they teach their own students down the road. So there’s more to the natural sciences and biology in particular than just a future career in the sciences. I think that we all need to have some ecological perspective in order to live in the world that we live in now.
This interview has been edited and condensed for clarity and length.
