Graduate Student Spotlights

September: Jacob Berv

Broadly, I am interested in the interface between micro and macroevolution, and how microevolutionary processes generate macroevolutionary patterns. I don’t believe micro and macroevolution are different phenomena. Rather, I believe that they are different manifestations of the same underlying process. As such, I am interested in whether or not there are ‘universal laws’ that govern connect and govern evolutionary processes at multiple scales, through time and space. Some of the questions that guide my research include: How do the actions of individual organisms and/or the characters of species propagate through evolutionary scales to generate phylogenetic patterns? Likewise, how might phylogeny constrain evolutionary potential? What are the roles of evolutionary contingency and convergence in generating patterns of biodiversity?

One of the manifestations of this set of questions is a pronounced heterogeneity in the rate of evolution across the tree of life. Rather than proceeding in a clock-like manner, the dominating signal of evolution at deep phylogenetic scales seems to be one of spurts of change interspersed with periods of (relative) stasis. Such patterns are captured both in phenotypes (in the fossil record), and in the genomes of living taxa. In birds, I recently documented  that heterogeneity in rate of molecular evolution across birds may be particularly extreme; the fastest evolving bird lineages (at least in terms of DNA sequences) seem to be evolving almost twenty times faster than lineages evolving at the slowest rates. It turns out that the rate of molecular evolution in birds is highly correlated to life history evolution.

In addition to my research, I’m very interested in how best to teach macroevolutionary thinking. While at Cornell, I’ve designed and taught my own curriculum in three macroevolution-focused ‘writing in the majors’ seminars. Over the last few years, I’ve also given a number of public outreach lectures to try to directly connect with non-academics and to explain where some of their tax dollars are going. Working with the Laboratory of Ornithology also empowers me to communicate the results of my work to the public through various media outlets. I recently had an opportunity to consult on the reboot of ’The Magic School Bus,’ which is now on Netflix. Going forward I am excited about the possibility of contributing to other educational programs as well.

In the time I’m not thinking about evolution, I can often be find on various social media platforms (@jakeberv), or consuming all kinds of movies, TV, art and music. I also used to be pretty into photography and am now rediscovering it as a creative outlet—hopefully will get back into sharing stuff on the web soon.


Jake with exposed K-Pg boundary layer in southern Saskatchewan


September: Lina M. Arcila Hernandez


I am a PhD student in the Agrawal lab studying local adaptation in insect-plant interactions. As a biologist, I enjoy looking for patterns in nature! I am obsessed with the variation of behavioral patterns that I find among populations of insects and how that relates to geographic gradients and the relationship with their host plants. Currently I am working on understanding whether behavioral traits in specialized insects are locally adapted and the consequences for population divergence in coevolved systems.

Milkweeds and the community of insects they support are a great system to work on the topic of local adaptation because the plants and insects have adapted to each other: milkweed plants produce latex and cardenolides, secondary metabolites that are really toxic, and the specialized insects that feed on them have physiological and behavioral traits to counteract these toxins. If a milkweed population becomes more or less toxic, it might determine what type of insects can survive on that population.

I spend my summers looking for milkweed patches, hunting for milkweed stem weevils in the Northeast and Midatlantic regions, and performing behavioral assays in the greenhouse or in common gardens in the field. I am also starting to use landscape genetic tools to understand the demography and evolutionary history of these weevils, so ask me a bit more about that in a few months.

To learn more about the distribution of milkweed stem weevils, I started a citizen science project that you can get involved with! Check it out here:

When I am not working on my research projects, I work on increasing and maintaining diversity in the sciences, learn and hopefully apply different teaching methodologies to improve STEM education. In my free time, I do all the things that Stepfanie does in her free time. Except for the dog part because I have a cute cat instead. Stepfanie we should talk more!  I guess I also spend a big part of my days reading news about Colombia, Canada, and the USA, and daydreaming about bats and rafting.



August: David Chang Van Oordt

I’m a second year PhD student in David Winkler’s lab studying the role of bird migration on parasite-host interactions. I am interested in the role that host migration plays on the transmission of avian malaria and how it affects the diversification of parasitic organisms. Long-distance migrants such as Tree Swallows have the capacity tocarry around different strains and connect parasite communities across large regions. I work with two species of swallow – Tree Swallows (Tachycineta bicolor) in the US, and White-winged Swallows (T. albiventer) in Peru – to compare how different migratory regimes, and life histories affect transmission of avian malaria and connectivity of parasite communities.

Besides my research, I’m very interested in encouraging and strengthening science, conservation, tropical biology, and education in my home country: Peru. I mentor students through the REPU program and actively look for new ways to contribute in Peruvian organizations. In my free time I like taking pictures, watching movies, TV shows and YouTube, reading, and playing volleyball. Lastly, I’m – relatively – active in social media (@davidchvo) to talk science, nature, graduate school, and Peru!




July: Stepfanie Aguillon


I am a third year PhD student studying hybridization in birds in Irby Lovette’s lab. Hybridization is extremely common in nature, and we can use naturally hybridizing organisms to understand speciation–or how and why new species arise. I am currently working on this problem in the northern flicker (Colaptes auratus), a common woodpecker across North America. The northern flicker includes two main subspecies – red-shafted and yellow-shafted flickers – that hybridize in a large hybrid zone from northern Texas to southern Alaska, following the Rocky Mountains. I use a combination of field and molecular methods, but also spend a good deal of time on the computer analyzing data.

Outside of my dissertation research, I’m interested in increasing diversity in the sciences, research on teaching, and mentoring students. I like to spend time with my partner and our dog, cross-stitching, reading comics, and watching movies and TV shows. I tweet about science and life with the handle @s_m_aguillon.





June: Katherine Holmes


How do indirect interactions structure plant-insect communities and drive the evolution of plant traits? This is the question I am excited to pursue with my thesis research. In the common evening primrose (Oenothera biennis), I study the function of flowers in an asexual species. In the absence of a need for pollinators, does the genetic variation provided by a low level of outcrossing maintain floral display? Or do flowers convey a fitness benefit by attracting predators, a form of indirect defense against herbivores? In another project with spotted Joe Pye weed and white boneset (both of Eupatoriinae), I am interested in how competition among neighboring plants is impacted by associational susceptibility and resistance to herbivores. Understanding the relative strength of such neighbor effects could help explain the ecology and evolution of plant growth and defense traits.

I also work in community outreach and science education, hoping to increase public access and understanding of science. I like to practice talking science, from teaching second-graders about insect communication to guiding high-school students through their science projects. My other pursuits include political advocacy and helping recruit a more diverse cohort of new ecologists. In my free time I experiment with baking, read science fiction and fantasy, and explore virtual worlds like Breath of the Wild. Oh yeah, and I work on this website!


May: Aubrie James


I am a fourth year PhD student in Monica Geber’s lab. I am working on understanding how four species of Clarkia, an annual wildflower native to California, interact when they’re neighbors. When you see one Clarkia species, it is likely that you will find another close by–they occur together in plant communities more often than not, and actually have been shown to benefit from living with each other. Why do these particular plants seem to get along so well? In part, it is due to the fact that Clarkia species share pollinators. In flowering plant communities, we generally see that more plants attract more pollinators, so living in a dense, diverse Clarkia community should be a good thing for Clarkia plants in need of pollination. However, with more plants comes more competition for other resources, such as water and light. My work focuses on determining if and when the benefits of pollinator attraction outweigh the costs of competition that Clarkia plants incur from living in dense and diverse Clarkia communities.
Aside from my dissertation work, I read, think about, and try to help disrupt and dismantle power dynamics that hurt people in and outside of the academy. I also enjoy hiking, catching bees, fishing, prime numbers, and naps.



April: Kate Eisen


As a third year PhD student, I am studying how community context affects the ecology and evolution of species interactions. Currently, I am addressing this very broad question in communities where flowering plants share animal pollinators. To me, flowers are the most exciting and incredible parts of these plants because their often flashy traits like color, spotting, and scent, have evolved to attract pollinators who facilitate reproduction. Thus far, I have conducted a greenhouse common garden experiment, an observational study of natural communities, and an experimental manipulation of these communities to address how pollinator sharing affects the evolution of floral traits in Clarkia (Onagraceae) in Kern County, California.

I think that connecting with people outside of the academic community is one of the most important things that I do as a scientist. Currently, I’m volunteering as a scientist mentor for PlantingScience, an online platform that provides teachers with different plant science curricula and pairs student teams with scientists who provide feedback and encouragement while the students conduct inquiry-based projects. Outside of science, I enjoy rock climbing, yoga, travel, and baking.

March: Tram Nguyen

I am broadly interested in conservation genomics and evolutionary biology. I am working on a landscape genomics study to assess the genetic structure and diversity of Florida scrub-jay populations across the state. I also hope to better understand how region of the genome change or evolve through time in populations that are rapidly declining.

As a woman in science and a first-generation college student, I am passionate about increasing diversity within the sciences. I have worked closely with organizations, such as Be WISE, to help empower and inspire young girls to pursue careers in STEM fields. I want to continue being a part of these efforts to promote inclusion and diversity in academia throughout my career. When I’m not buried in research, I love going to the beach, painting, petting dogs and rolling around on my skateboard 🙂