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Emily Le Sage, PhD

Integrative biologist in translational ecology

Dedicated to promoting diversity of both identities in STEM and life on our planet!

Find me on the oSTEM Mentoring Program

Science is for everybody
Las ciencias son para todas

About me

Motivated by global biodiversity loss, my research program focuses on how global change influences infectious diseases dynamics in wild vertebrates. Specifically, I integrate physiology and disease ecology in a translational ecology framework to address fundamental and applied questions.

With recent evidence suggesting populations are recovering after invasive pathogens caused severe declines, my research program capitalizes on this exceptional opportunity by seeking mechanisms underlying this variation in multiple study systems. By co-producing research with practitioners, we can apply this knowledge towards developing innovative solutions to disease-related biodiversity loss.

To tackle these multifaceted issues, I apply team science principles to collaborations consisting of diverse perspectives, identities, and expertise. My teaching and mentoring practices focus on building interdisciplinary learning, international awareness, and leadership skills.

I'm also an artist, gardener, and I love exploring the natural world. Here's my rendition of Rosie the RIBBiTR, our BII's mascot!

Rosie copy transparent.png

Recent news

Jan 4, 2023 - Habitat split could increase stress induced susceptibility to amphibian disease


In this review paper, coauthors and I discuss potential mechanisms in which habitat split, a phenomenon in which the necessary habitats to complete an animal's life cycle are separated by lower quality habitat such as agriculture or urban areas, could affect amphibian responses to disease. Excited to continue collaborating with this team to dive deeper into the relationship between glucocorticoids, the microbiome, and behavior when frogs are facing these challenging conditions in Brazil's Atlantic Forest. Email me for a PDF to read more!

Oct 10, 2022 - 'Socially distancing' wood frogs could reduce ranavirus transmission


With the pandemic, many of us are familiar with the concept of social distancing to reduce the chances of becoming infected. But how common is this behavior across animal groups? My student collaborator and coauthor on this recent publication, Molly Diamond, creatively pursued the question of whether frogs display an avoidance behavior when introduced to a ranavirus-exposed frog. We not only found that they distanced themselves from an exposed frog, but the distance was greater with more intensely infected focal animals! This is not only important for better understanding animal behavior, but ranavirus infections are a concern for several amphibian species in decline. Prior to this we were not sure that ranavirus transmission occurred during the terrestrial life stage when animals are moving from pond to pond. Email for a PDF to read more!

Sept 22, 2022 - Differential expression of behaviors span latitudes

Building off our previous work demonstrating that wood frog populations exhibit ecological adaptations to climate and conspecific density in life history traits, we found that these same populations display differential expression of juvenile behaviors. Perhaps shorter growing seasons or higher competition has selected for juveniles with a greater propensity to explore and forage at higher latitudes, perhaps the historical expansion into the Northeast explains these differences. I'm excited for future work to dive into the many new hypotheses generated from this major effort. I'd like thank all of the hardworking helping hands in making this happen from our NSF grant awarded to Erica Crespi and Leslie Rissler.


Access the paper for free here:,2iMaHDT

May 14, 2022 - Developing in a drying pond reduces pathogen defenses:

Climate change is increasing the chance that ponds dry up before the animals that depend on them can finish growing and metamorphose into their terrestrial life stage. In this cross-scale, cross-country, collaborative project, we found that although populations differed in their responses to pond drying, there were often consequences of developing in decreasing water levels. The major differences were in their microbiomes, which help them fight fungal infections, and how well they fought off the fungal infection in the lab. Access the PDF on my publication page.

March 3, 2022 - Honored to hear that 'Preparatory immunity' was shortlisted for JAE Elton Prize!

September 22, 2021 - BII funded to study ecological resilience:


Our Biological Integration Institute proposal was funded by NSF! Meet RIBBiTR, the Resilience Institute Bridging Biological Training and Research. Congratulations team, I am thrilled to continue our integrative work to gain a deep understanding of how biological systems achieve resilience to emerging infectious diseases and other global change stressors.


Feb 2, 2021 - "Country" frogs aren't adapted to living in dense "city" conditions


In our recent study published in Heredity, the latitudinal cline in body size found in wood frogs appears to be driven by isolation by ecology rather than geographic distance. Our results suggest that both climate and conspecific competition (competition with individuals of the same species) selection pressures drive population divergence in developmental traits in this species.


Range-wide studies like this one are essential for accurate predictions of population’s responses to ongoing ecological change. Access the PDF on the publication page.


Nov 12, 2020 - Winter is coming: Do frogs prepare their constitutive defenses for the cold?


Like many animals, frogs have seasonal infectious disease patterns. We wondered if their pathogen defenses also displayed seasonal rhythms, and were surprised to find that their stored peptide defenses closely followed the pattern of infection peaks in time. This synchrony between host and pathogen could be a result of similar underlying environmental forces, such as temperature, or a evolutionary arms race in which frogs prepare for the worst.


Our latest study tracks leopard frog peptide and microbiome defenses through seasonal changes in Batrachochytrium dendrobatidis (Bd) infection prevalence and microclimate. Access the PDF on the publication page.


May 6, 2020 - Stress increases the severity of epidemics


In the time of a global pandemic, understanding how stressors lead to more susceptible and infectious hosts is increasingly relevant. Similar to humans, chronic stressors are known to suppress immunity in frogs. But how do they affect epidemics? Predicting these sporadic and non-linear events requires a deeper understanding of how poor conditions affect interacting epidemiological factors to cause more severe and more frequent epidemics. See the press article in Forbes and access the PDF on the publication page.

Apr 23, 2019 - Battle of host and pathogen


Another great study out by the Rollins-Smith lab identifying more ways the pathogenic fungus Bd (Batrachochytrium dendrobatidis) can knock down a frog's immune defenses. Discoveries like these can be a foundation for research that helps humans and frogs combat diseases and cancer. See our press article here.



October 22, 2018 - Seasons may change, and so do disease dynamics


Using the exciting new method of environmental DNA sampling, we were able to take the first glimpse at how a community of amphibians experiences a ranavirus outbreak. Identifying how the epidemic curve relates to eDNA levels in pond water can help field biologists determine if a population is at risk--just by taking a water sample. Here we determined that mortality occurred during sensitive developmental windows once pond temperatures were warm.


August 4, 2018 - A blue frog in TN?


Ever wonder what makes a frog green? While sampling for amphibian diseases on the Air Force Base near Tullahoma, TN, we encountered a sight rarely seen. A leopard frog, which is usually green, with mottled blue skin!


Axanthic means "without yellow". When blue and yellow pigment layers combine we see green skin, and when yellow is missing, the blue shines through.


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