Five questions for Rebecca Safran

Assistant professor, Ecology and Evolutionary Biology, CU-Boulder

Rebecca Safran (Photo courtesy of Rebecca’s husband, Sam Flaxman, also an assistant professor in the Department of Ecology and Evolutionary Biology)

As a child, Rebecca Safran wrote and created a magazine that she sold to neighbors. She assumed she would be a writer until she took a class in plant taxonomy during her undergraduate years at the University of Michigan. While on field trips she began to see the world around her in a different way, and she became passionate about biology.

“The deal was sealed after spending a summer at the University of Michigan’s Biological Station during my undergraduate education,” she said. “There I got to take classes from and interact with some of the brightest minds in biology. I was in awe!”

After earning a master’s degree in wildlife biology at Humboldt State University and her doctorate in ecology and evolutionary biology at Cornell University, she did postdoc work at Princeton University from 2005 to 2008. Then she joined the University of Colorado Boulder, where currently she is an assistant professor in the Department of Ecology and Evolutionary Biology.

“I love biology and I love history,” she said. “In many ways, evolutionary biology is focused on discovering and testing hypotheses about the history of life on our planet. For example, how and why things look the way they do and how and why there are species in one place, not another, and why some lineages end up splitting into many, many species while others go extinct. These questions and many others like it are endlessly fascinating to me.”

Her research on barn swallows includes examining phenotype (observable characteristics) and how these traits differ in sub-species. A particular interest is in the role of sexual selection, and past studies have looked at how features of morphology are related to physiology/genetics. One surprising finding is that by simply darkening a male’s appearance to match the darkest males in the population, researchers also altered the bird’s physiology: Males whose appearance is manipulated experience shifts in testosterone profiles. The research also helps illuminate why females choose males based on different traits.

1. You recently won a National Science Foundation Early Career Development, or CAREER, award to study genetic differences in barn swallow populations to gain a greater understanding of how new species are formed. Why did you choose to study barn swallows as opposed to another bird?

Barn swallows are one of the most widespread species of vertebrates worldwide. During the breeding season, their distribution encompasses most of the Northern Hemisphere. Barn swallows are composed of at least six sub-species – populations that have been indicated as different from one another in several ways.  In evolutionary timescales, this is a very young collection of sub-species, meaning that they have evolved from one another very rapidly and are still doing so today.  Despite this, populations of barn swallows look and behave quite differently from one another: Some migrate during the winter, others do not, and males also possess different traits used to attract females.

Our previous experimental work indicates that feather color and the length of outer tail feathers – which differ in males depending on where you study them – are related to mate-selection decisions made by females in these populations. So, for many reasons, the barn swallow study system represents an exciting opportunity to study evolution in action. In particular, in this new grant we are using the tools of genomics to discover how different features among these closely related populations are related to signatures of population divergence in the genome. Within the five-year period of this grant we will certainly be able to amass an enormous database to tell us a great deal about population genomic divergence among 55 different sampling locations – spread throughout the entire breeding range of our study system – and how it is being influenced by climate variation, migratory behavior, morphological variation and many other features.

2. The study includes other collaborators in 35 countries. How will the study be conducted?

Each summer, a number of countries and locations will be visited. I have established collaborations at each of these sites, which alone took nearly two years of persistent emailing! I wanted to be sure that the coverage of sampling was adequate to capture variation among and within different sub-species – across different continents and within them – across different latitudes. Every summer for the next five years will be composed of a lot of international travel to capture and collect samples from barn swallows from around the world, from Egypt to Kazahkstan, throughout Russia and China, and most of North America. We will be bringing back samples to my lab in Boulder to conduct all sorts of molecular analyses, including those related to genomic divergence, but also to assess migratory behavior through the use of stable isotope analyses and many other assay that will tell us something about individuals in each population. Ultimately we aim to learn a lot about how these factors – including climate variability -- influence the process of speciation.

3. Part of the award includes a “Citizen Science” program. What does that entail?

Our work on barn swallows takes place on mostly private property, and we do very much rely on these property owners to provide us with access to their barns (and thus, swallows!). It is a special landowner that really allows us to do our work well – which often means checking nests a few times per week, and arriving to set up nests to catch birds before dawn.  Most of these people are very interested in our work and it’s wonderful to think of ways to formally involve them in some aspects of it. For this grant, we are hoping to set up a website where landowners can track simple metrics that collectively can tell us a lot about seasonal and timing changes in barn swallows: first date of arrival in spring, date of departure in late summer and fall. These observations are simple enough to keep track of but are quite important for looking at larger scale patterns of the timing of the breeding season and how it is changing from year to year. The data will help us determine when our field studies begin and end each year but more importantly will provide the start of a hopefully longer-term project on breeding schedules and climate change.

4. What would you consider your proudest achievements?

Getting the CAREER award was a biggie. It’s very competitive and I was lucky to win the award on my first try. It is truly an honor and one that I will take full advantage of. That aside, I am extremely proud of my graduate students. I had no idea how to mentor them when I first started my position and my first two Ph.D. students have been through several trials and errors of different mentoring styles. They have been very patient! It has been so exciting to see them work toward and achieve their goals!

5. What do you enjoy most about teaching and what do you want your students to take from the classroom?

As a research mentor, my number one goal is to inspire students to be curious and to ask good questions. This can only be accomplished by having a deep knowledge of what has been done, so I encourage them to understand the backgrounds of their various fields of interest inside and out.  My teaching is quite variable from term to term. In the fall, I teach a 20-student class on climate change and film where the students are asked to digest facts and views about climate change and to make two independent short films based on their assessment of the situation. These films are shared within and outside of CU and they have to tell a story that is heartfelt. My spring class is for 700 students of General Biology. Here, I don’t get the pleasure of knowing each student very well, but the challenge is instead to try to engage them to relate the material at hand in some way, shape or form.  In this setting, a primary wish of mine is to have my students think for themselves (what do they understand, what is not clear and why) so that true, deep learning can really happen.

Home page photo by Kevin Stearns