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MAJOR UPDATE: As of May 31, 2023, I will be a tenure-track junior professor at the University of Bremen! Eventually, the contents of this website will be transferred to their website and expanded for my new lab group. In the meantime, this website will remain available, but no longer updated. Relatedly, I am searching for a PhD student to join my new group, see this description if your are interested: Nielsen_Bremen_PhD hiring description

I’m an evolutionary ecologist studying how organisms respond to rapid changes in their environment, particularly anthropogenic changes like climate change and urbanization. I’m especially interested in how responses on different timescales interact with each other, from the near-immediate response provided by behavior, to within-generation phenotypic plasticity, to the multiple-generations required for adaptive evolution. Most of my research has focused on temperature because it’s ubiquitous, highly variable, and affects most aspects of biology. Climate change makes understanding responses to temperature particularly important, and the research I’m proudest of has directly measured evolutionary responses to climate change. My research combines field and museum-based observational studies with field and lab experiments on live organisms. I work with a wide variety of traits, from color and morphology to behavior to life history, and often consider how these different types of traits interact with each other. Currently, I’m a postdoctoral researcher at the University of Oulu with Sami Kivelä, applying my interests in phenotypic plasticity and local adaptation to study how butterflies and moths are evolving in cities.

I received my PhD in Ecology and Evolutionary Biology at the University of Arizona (2010-2016), where I worked with Dan Papaj studying the interactions between color plasticity and behavior in thermoregulation by Battus philenor caterpillars. During the latter part of my dissertation, I also spent time working with Johanna Mappes at the University of Jyväskylä looking at how color and behavior jointly affect temperature and predation risk in Artica plantaginis caterpillars. My first postdoc (2016-2019) was at the University of North Carolina in the lab of Joel Kingsolver where I studied evolution of seasonal plasticity in Colias eurytheme butterflies in response to climate change. My second postdoc (2019-2021) was at Stockholm University with Karl Gotthard, where I studied how the use of photoperiod as a cue for seasonal life history plasticity has evolved in association with both climate change, using a variety of butterfly species.