Safran Lab @ the University of Colorado, Boulder. Integrative Evolutionary and Behavioral Ecology
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Dr. Loren Merrill
​Research Affiliate 2019  -


​Loren is a research affiliate in the lab as well as at the University of Illinois, Champaign-Urbana, where he worked as a postdoctoral researcher and fellow. Loren conducted his Ph.D. at the University of California, Santa Barbara with Dr. Steve Rothstein examining the relationships among reproductive strategy, sexual signals, immune function, and glucocorticoid hormones in the brood parasitic brown-headed cowbird and its non-parasitic relative, the red-winged blackbird. Loren did a one-year postdoc at Oklahoma State University with Dr. Jennifer Grindstaff focusing on the role of early-life stress on a suite of behavioral, morphological, and physiological traits in zebra finches. His research focus now combines landscape ecology, ecophysiology, parasitology, and behavioral ecology to understand how early-life conditions impact short and long-term growth and condition in wild birds. Loren is also an avid nature photographer and writer, and has been writing a blog that combines his love of natural history with his love of photography. To read his blog click on the link: https://lorenmerrill.weebly.com/theviewoutthedoor
and for his homepage click here: https://lorenmerrill.weebly.com/

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Dr. Angela Medina-García
NSF Postdoctoral Fellow January 2018-May 2021

PhD, New Mexico State University (2017)
MS Biology, Bowling Green State University (2011)

Understanding the evolutionary mechanisms that have shaped animal cognition is a cornerstone of animal behavior research. Cognitive processes govern many aspects of an individual’s life and thus cognitive abilities have an immense impact on fitness. In order to understand how animal cognition has evolved, it is paramount to quantify individual variation in cognitive traits across individuals, to examine non-cognitive factors that potentially influence this variation, and to examine fitness consequences of cognition. My dissertation focused on the role of mate selection in the evolution of cognitive traits and the impacts of such traits on male reproductive success in budgerigars. I also examined the effects of personality and physiological response to stress on individual variation on cognitive performance.
 
Barn swallows breed either in solitary pairs or in colonies with multiple breeding pairs. Therefore, this species is an ideal system to make ecologically and phylogenetically controlled comparisons of cognitive traits among individuals of the same population with a varying degree of sociality. I obtained an NSF postdoctoral fellowship to evaluate the impacts of social breeding on the evolution of cognitive traits. I am currently  measuring individual variation in cognitive traits and their impact on reproductive success. I will also test natal and environmental influences on these traits tested along a low-high degree of sociality continuum. 

Read more about Angela here 

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Sage Madden
Honor's thesis student/ NSF REU student summer 2020
Fall 2018 - Fall 2020 


Sage is broadly interested in the fields of animal behavior and conservation biology. She is  particularly interested in how organisms adapt to novel environments and how wildlife and humans interact in anthropogenic landscapes. Sage is currently working on an undergraduate Honors thesis in the Safran lab examining how female Barn Swallows alter their foraging and parental care behavior in response to changes in brood size. She has been working closely with PhD student Molly McDermott since Fall 2018.


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Jonté Allen
​BA student Spring 2020 


Jonté Allen is a senior in the CU Boulder EBIO department who is currently interested in the application of evolutionary theory in human development at the individual level as well as the species level.  Specifically, he is fascinated by the development of cognition, large social structures, language, and cultural traditions.  Also among his interests are the relationship of commensalism and intellectual development, the consequences of instinct upon individual psychology, the application of evolutionary concepts to seemingly unrelated disciplines, the ongoing evolution of humanity through sexual selection, and the field of scientific education.  When not studying, he can be found on the soccer field in the summer and on the ski slopes in the winter.  

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Chris Smith
​PhD candidate

NSF Graduate Research Fellow, BioFrontiers Fellow. Fall 2014 -2020

BS Univ Texas 2012
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Chris is an honorary member of the lab. He is co-advised by Sam Flaxman and Nolan Kane and his doing his dissertation research on demographic analyses using genomic data sets from barn swallows.  Chris graduated from the University of Texas in 2012, worked at UC Davis in Mike Turelli's group from 2013 - 2014 and joined CU's Interdisciplinary Quantitative biology (IQ BIO) program in Fall 2014.  You will mostly find Chris coding on his laptop somewhere but we had to at least get him out to the field once to check out the barn swallows (pictured here).

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Ellen Scherner, BSI, NSF REU student 
Summer 2019- Summer 2020

Ellen worked closely with our team during the field season in 2019 and is currently analyzing from several field experiments, in collaboration with postdoc Angela Medina Garcia.  She hopes to conduct an acoustic analysis of Barn Swallow alarm calls throughout the semester as well. In the future, she plans on continuing her educational journey in research, hopefully in conservation or wildlife biology.

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Bryan Martino,  Independent Research
Spring 2020 


Currently a sophomore undergraduate, double-majoring in EBIO and Environmental Design,  I’m interested in discovering how male and female barn swallows differ in their carbon isotope ratios, and how this reflects the ecologies of their winter habitats. Another objective is to cultivate skills in stable isotope analysis to prepare me for climate-related research in marine sciences. In the larger field of evolutionary biology, I’m most passionate about sustainability and climate resilience of species. Creative skills in design practices will help me examine how the built environment can better integrate the natural world in context to a growing need for such resilience. Outside of lab, I love to run and spend time with the CU Bee Club!

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Noah Goodkind,
​BSI, Independent Study Summer and Fall 2019

My broad area of interest is centered around human management of natural lands and resources. I find the question of how to balance the needs of society versus maintaining a healthy environment an interesting and tricky one. My current project revolves around using GPS and land cover data to try and determine land or water features that the birds forage near.

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Brittney Lafond Independent Study
Fall 2019 - Summer 2020

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Brittney's research interests include anything that involves animals in some way. Specifically, she loves learning about how alterations to an environment or mating practice can impact members of a species. So many species have unique behaviors or appearances that have yet to be fully explored and she is interested in any kind of research that delves deeper into the why of species behaviors. Brittney is currently investigating how altering brood size and the addition of a physical handicap may impact the immune status of female barn swallows. 

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Sheela Turbek
PhD candidate
NSF Graduate Research Fellow
Fall 2015 - Spring 2019

BA Bowdoin College 2013


Behavioral and phenotypic traits are thought to play a key role early in speciation by influencing where and when individuals come into contact and whether closely related organisms are recognized as potential mates. I am studying the prevalence and mechanistic basis of assortative mating in two recent avian radiations: the barn swallow species complex and the southern capuchino seedeaters, a highly sympatric radiation in South America, to better understand the processes that limit gene flow during incipient speciation. Barn swallows exhibit extensive variation in migratory behavior, while capuchino seedeaters are characterized by striking differences in male plumage coloration and song. My research combines fine-scale behavioral analyses with phenotypic and genomic data collected in areas of geographic contact between closely related species to investigate the importance of pre-mating processes for the generation of biodiversity.

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Georgy Semenov
Postdoctoral Fellow
Feb 2018 - Feb 2019


I am broadly interested in studying the mechanisms of adaptation and speciation. In particular, I take advantage of avian hybrid zones to infer what components of phenotypic and genetic variation act as barriers to gene exchange between nascent species and what processes promote and maintain such variation.

Barn swallows have a number of features in common with the white wagtail – a bird I studied throughout  my master's and doctoral research.   Both species underwent recent and extensive phenotypic diversifications and have multiple hybrid zones across Eurasia, presenting great study systems for asking key questions in evolutionary biology.  At the University of Colorado I will use genomic tools to study genetic basis of migratory behavior and its contribution to the patterns of phenotypic and genomic divergence across the barn swallow subspecies.

To learn more about Georgy, go here 

Dr. Liz Scordato,
NSF Postdoctoral Fellow
​Nov 2012 - Nov 2017

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BSc Duke University 2004
PhD University of Chicago 2012


My research focuses on determining causes of variation in sexually selected traits, and understanding the consequences of this variation for population divergence and speciation. In my doctoral work, I studied how inter- and intrasexual selection interact with environmental variability to drive divergence and generate prezygotic reproductive barriers in the greenish warbler (Phylloscopus trochiloides) ring species complex of Central Asia. 

At the University of Colorado, I am working on the genomics of population divergence in the barn swallow (Hirundo rustica) complex. This widespread species has recently diverged into several subspecies that differ in plumage phenotype and migratory patterns, yet remain apparent ecological equivalents. Using a combination of intensive fieldwork, quantitative genetics, and next-gen sequencing, we are assessing the relative contributions of divergent natural and sexual selection (i.e. isolation by adaptation) vs. isolation by distance to both phenotypic and genomic divergence in this group.   


​Liz is now an Assistant Professor at Cal Poly, Pomona. Read more about Liz here

Amanda Hund, PhD student, Fall 2011 - Fall 2017
​NSF Graduate Research Fellow

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BA Carleton College 2010

On a large scale I am interested in how new species form and in the underlying causes of diversity.  In particular, my research focuses on how sexual selection and parasites could be mediating speciation across closely related populations. I am hoping to better understand how coevolution between hosts and local populations of parasites could act as a selective force to create reproductive barriers. Using three different barn swallow subspecies with divergent sexual selection, I am studying what information different sexual signals are giving to females about parasites, immune systems, and nest environments. In order to look at what females gain by choosing attractive mates and how this could be changing across populations, I am looking across a wide range of avian parasites and immune measures, as well as performing field experiments (cross-foster). Initial data suggests that the expression of different sexual traits links with parasite loads on males in at least two subspecies- suggesting that these traits could be advertising information about parasite resistance, and that this is changing across subspecies.

Amanda is currently a postdoctoral fellow at the University of Minnesota.

Read more about Amanda here

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Kyle Donahue, BA-MA student, Fall 2015 - Spring 2016

BA University of Colorado 2015
MA University of Colorado 2016


Kyle completed an honor's thesis in our lab group on fine-scale nest movement decisions of barn swallows. He stayed on to do exceptionally well in the BA-MA program and completed his MA in spring 2016.  For his MA degree, Kyle studied the role of predation and parasites on nest site selection patterns of barn swallows. Read Kyle's recent publication here.

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Iris Levin, NSF postdoctoral fellow, 
May 2014 - July 2016
BA Bowdoin College 2005
PhD University of Missouri - St. Louis 2011


Iris was awarded  a National Science Foundation Postdoctoral Research Fellowship, Intersections of Biology, Mathematics, Physical Science and Engineering to work on social networks.  

The goal of my postdoctoral research is to understand the interface between social behavior, physiology and parasite transmission by testing hypotheses that integrate themes from evolutionary biology, behavioral ecology and wildlife epidemiology, within the mathematical framework of social network theory.  There are gaps in our knowledge of social transactions related to the difficulty obtaining accurate measures of social interactions, the lack of experimentation within social networks, and the analytical challenges associated with robust statistical comparisons of networks.  We are currently working with Dr. John Burt, who develops Encounternet digital transceiver tags for obtaining social contact data, and Dr. Juan Restrepo, an applied mathematician who specializes in network dynamics. 

Iris is currently an Assistant Professor of Biology at Kenyon College. 

Read more about Iris here

Joanna Hubbard, PhD
​Fall 2008 - Fall 2014

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BS University of Arizona 2004
MS College of William and Mary 2008


I am broadly interested in the evolution and maintenance of of sexual signals. More specifically, I am interested in understanding the proximate and ultimate mechanisms that control plumage color in birds. My dissertation research focuses on understanding the color variation seen within and between subspecies of barn swallows. I am using a quantitative genetics approach to understand the roles that genes and environment play in the development of phenotypic variation. Preliminary results suggest that both genes and environment are significant sources of phenotypic variation and I am currently working to isolate the effect of each individually. I am also using a candidate gene approach to explore allelic variation in known vertebrate pigmentation genes between phenotypically divergent populations. By using a comparative framework, I hope to provide a better understanding of how variable selection on ventral plumage color between populations has contributed to population divergence in the barn swallow species complex.

Joey recently moved to Truman State University where she is an Assistant Professor of Biology.


Read more about Joey here

Cait Dmitriew, NSERC postdoctoral fellow 2011-2014

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BSc University of Toronto 2003
PhD University of Toronto 2010

Broadly, my research interests lie in understanding the origins of diversity.  My doctoral thesis examined why organisms often grow at submaximal rates, despite the known advantages of large body size and rapid development times.  Ongoing research looks at the factors that maintain genetic diversity in traits under selection, including environmental variation and genic capture.

At the University of Colorado Boulder, I am studying the role of sexual selection in the among-population diversification of the black scavenger fly Sepsis punctum.  Populations of this geographically widespread species vary dramatically in the magnitude and direction of sexual size dimorphism, as well as in mating behavior.  The relative roles of sexual and ecological selection in promoting reproductive isolation remain controversial: by observing mating behavior within and among populations, I can assess the role of sexual conflict and female preferences in driving reproductive isolation of ecologically similar species.

Matt Wilkins, PhD, Fall 2008 - Spring 2014

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Matt completed his PhD, entitled "Evolutionary divergence in sexual signals: insights from within and among barn swallow populations." After working as a postdoctoral fellow at the University of Nebraska-Lincoln, with Drs. Dai Shizuka and Eileen Hebets, Matt is now working on Science Communication as a fellow at Vanderbilt University.

Find out more about Matt's terrific research and science communication work here.

Yoni Vortman, PhD, Fall 2008 - Fall 2013

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Yoni completed his PhD at Tel-Aviv University and is co-advised by Dr. Arnon Lotem and Rebecca Safran. Yoni is currently an Assistant Professor of Biology at Tel-Hai College,  Israel.

I am interested in the evolutionary forces driving the endless variation in nature. Specifically I am interested in cases where selection on the individual, such as mate choice and sexual selection, and population level forces, such as gene flow and genetic drift, interact.  

Yoni is now an Assistant Professor at Tel-Hai College, Israel. Read more about Yoni here. 


Rachel Wildrick, BA-MA student,
​Fall 2008-Spring 2013

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BA University of Colorado 2012
MA University of Colorado 2013

I am interested in how small-scale interactions can determine broad-scale species patterns and change; how mate-choice can shape population divergence, or how individual experiences produce patterns of age-related reproduction. For my honor and master’s theses, I have focused on how life history patterns of age-related reproductive performance are played out in an individual’s lifetime by studying the relative influence of different factors on reproductive success each year.  


Brittany Jenkins, MA Fall 2010 - Dec 2012

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I’m most excited about the physiological processes underlying sexually-selected traits. More specifically, I am investigating the relationship between the stress hormone corticosterone (CORT) and the sexually selected melanin-based plumage color of male North American barn swallows. CORT is important in initiating the stress response, which is aimed at increasing immediate survival when an individual is faced with a challenge (e.g. presence of a predator, competitive interactions). Therefore, it may play a crucial role in shaping behavior essential to survival and reproduction, and plumage color could signal to potential mates a male’s ability to cope with stressors. I am also looking at the potential for selection to shape individual variation in the stress response. Natural populations of avian species are highly variable in both baseline and stress-induced CORT concentrations, which is shown to be correlated with different measures of fitness. Part of my thesis research aims to elucidate the heritability of CORT, as well as the relationships of CORT profiles with reproductive success and survivorship.

As of fall 2015, Brittany is a PhD student at Montana State University.


Maren Vitousek, postdoc 2008 - 2012

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Maren worked on various questions related to the dynamic interactions between physiology, morphology and behavior with a focus on stress hormones and life history variation. Maren is currently an Assistant Professor in the Department of Ecology and Evolutionary Biology at Cornell University.  Read more about Maren's work here.

Roi Dor, postdoc 2011 - 2012

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Roi was a postdoctoral researcher in our group from summer 2011 through summer 2012.   Roi is currently an Assistant Professor at Tel-Aviv University.  Read more about Roi's work here. 

Andrew Flynn, BA-MA student 2008 - 2012

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Andrew completed a BA-MA degree in our lab. Andrew worked on questions related to nest predation, paternity and morphological variation in barn swallows.  Read more about Andrew here 

Inside the Greenhouse Project.
Learn more about our science communication action, research and teaching focused on climate change. 



Barn Swallow - Human Interactions: Art/Science Side by Side.
check out the amazing immersive website of Avani Fachon!


New Side by Side website is LIVE!

Check this out! stories from the field about our international barn swallow speciation project 








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