Indiana State University Newsroom

Harvard doctoral student comes to ISU to research with pioneering professor

May 18, 2012

Martha Muñoz had never spent more than a few days in the Midwest until she came to Indiana State University to work with George Bakken, a pioneer in biophysical ecology, a field Muñoz has been studying for many years.

The Harvard University doctoral student read Bakken's papers and was familiar with his work. Then, after meeting him for the first time at a scientific conference, she decided to travel from the Ivy League school to study at Indiana State.

At the conference, Muñoz gave a talk about her research into evolutionary ecology. Her presentation focused on how body temperature regulation influences evolution in Anolis lizards. Bakken attended her talk and saw potential problems with one of the tools Muñoz and many other thermal ecologists use to collect data. Afterward, he suggested that she visit his poster presentation later that day.

"I was very flattered that he was interested in my work, and after I read his poster it really became clear that I wanted to take this part of my work to the next level. The way to do that was to use his copper models," Muñoz said.

Bakken is a trained physicist who began working in biology in the 1970s as part of a Ford Foundation project at the Missouri Botanical Garden to create a bridge between the two disciplines.

"There were a lot of problems in environmental biology where scientists wanted to know how organisms related to microclimate - temperature, humidity, sunshine and other environmental factors where the animal lives," he said. "Studies were not being done very well because biologists took physics reluctantly, even though the problems could actually be solved quite easily using physics."

Bakken specifically looked at how and where measurements were being taken, and noticed they were in places where humans lived, not animals. Also, standard measurements failed to account for the great variation in conditions encountered by a small animal as it moved around. To remedy this, he developed an inexpensive instrument that could be used in large numbers and was small enough to place where animals were actually living.

Bakken focused on lizards because even in 1975 it was clear that global warming was coming. Lizards would be the "canaries" in the climate change "coal mine" because they are easy to study and strongly affected by weather and climate, he said.

"What was needed was an instrument that was the same size, shape and color as the animal but didn't have any metabolism, evaporation or behavior," Bakken said. "This gives a combined measurement of all the microclimate conditions experienced by that animal, without any need for calculations."

Bakken's instrument involves using hollow copper models of lizards containing a temperature sensor and painted to match the live animal. It worked so well it is now widely used by scientists around the world.

At first, models had to be connected to a central recorder by wires that often tangled with the feet of scientists. A great improvement became possible with the commercial availability of Thermocrons, inexpensive miniature digital temperature recorders that can fit in a small lizard model, left no wires to tangle, and dramatically reduced the effort needed to collect data in the field.

Bakken's poster at the conference described how to make a lizard model with an embedded Thermochron, and why the simpler instrument others had used (and that Muñoz planned to use) would not give reliable data.

After reading the poster, Muñoz decided to use the "latest model" microclimate sensors, and Bakken invited her to work with him in his lab at Indiana State to make the models she needed.

Muñoz spent two weeks on campus with Bakken in April and made 50 models of the Stout-headed anole (Anolis cybotes) to use when she returns to the Dominican Republic this summer to continue her research. Muñoz chose the stout-headed anole for a few very specific reasons.

"If I want to know how organisms are adapting to different environments, I want to focus on the species that is found in the greatest extremes," she said. The Dominican Republic has the highest elevation in the Caribbean. Stout-headed anoles can be found there at elevations from near sea level up to 2,500 meters, where the environment can be much colder.

The anole is a tropical lizard that prefers a high body temperature, so something is going on that enables them to live at such high elevations, Muñoz said.

What she has discovered is that, in order to thermo-regulate in different environments, the anole switches its perch from cold trees to hot rocks at higher altitudes. It appears that life on rocks is driving the evolution of flatter heads, probably because they can then squeeze into tighter cracks to avoid predators or to retreat during conditions too cold for basking or for other behaviors.

Muñoz's research focuses on how behavioral thermoregulation dampens selection on physiology, as anoles on rocks can maintain a temperature comparable to those found on trees at sea level. However, she found that the use of rocks was simultaneously driving morphological evolution. The idea that a single behavior can simultaneously impede and impel evolution in different traits has been hinted at in the scientific literature, but until now remained empirically untested.

Bakken and Muñoz said the utility of the copper models is that they possess the thermal inertia of a lizard, but cannot shuttle around the environment like their living counterparts. When 50 models are placed around the environment, they will depict the thermal environment from a lizards' eye view. In this manner, actual body temperatures recorded from living lizards can be statistically compared to the copper lizards to determine the degree to which the lizards are thermo-regulating.

Muñoz will return to the Dominican Republic in June for the third time, now with Bakken's models, to continue her research into thermal ecology, adaptation and evolution of the anoles found there.

"Science is an international cooperative endeavor," Bakken said. "No matter where you are or what school you are at, there is going to be somebody, someplace else that knows something you don't, no matter how smart you are. Scientists must go where they can get what is needed for a particular project. Attending conferences is very important, because that's where ideas and experimental methods are traded, and new research projects started. Martha improved her research project by coming to the meeting, just as my research benefitted from what I learned from someone at another meeting several years ago."

Muñoz is a first generation American, born in New York City to parents who had moved from Spain to Cuba, back to Spain and finally to the United States. She has been interested in evolution, ecology and nature since she was a child. Growing up in a small apartment in New York City did not give her much access to the field and green spaces, but she did have the American Museum of Natural History and the Bronx Zoo. These places were where she fostered and developed her interest in nature, and what motivated her to pursue a career studying the "real thing."

Now she says, "Basically I'm just an overgrown kid who has been allowed to pursue childhood interests and this is the realization of a childhood dream to interact with and try to understand nature."

"Every kid is a natural-born scientist, but most seem to lose it somewhere in middle school. Professional scientists are the ones that didn't,"

Bakken said. "Martha is now a very promising young scientist. She made full use of every opportunity to realize her dream. Harvard is very supportive of the idea that you should go wherever you have to go to get what you need, whether it is Terre Haute or the Dominican Republic. It was a lot of fun to have her here. She is a very interesting person because she has not had the easy road to success. But, just because life dealt you a difficult hand doesn't mean you can't play it well, and she has."


Photo: - George Bakken


Contact: George Bakken, professor of biology, Indiana State University, 812-237-2396 or

Writer: Alexa Larkin, media relations assistant, Office of Communications and Marketing, Indiana State University, 812-237-3773.