Tracy KarplusViews:
Authored by Chloé M. Allen-Love
Born and raised in northeast Georgia, I have called the Chattahoochee National Forest home and all of its wild inhabitants my family. As this forest has provided me sanctuary and protection throughout my life, I have dedicated my career to conducting research and making discoveries that can play an important role in conserving and protecting the forest and her inhabitants. In 2022, I received my Bachelor of Science in Pre-medical Biology from the University of North Georgia in Dahlonega. In 2023, I began pursuing my PhD at The University of Texas at Austin in the Integrative Biology Department’s Ecology, Evolution, and Behavior program. My research focuses on amphibian immunogenetics and global climate change, with the goal of understanding how environmental change and disease interact to threaten amphibian communities.
The first of my three dissertation chapters focuses on the seasonal prevalence of three important amphibian pathogens within a north Georgia amphibian community. I began sampling in June 2024 at the Charles Wharton Conservation Center in Tate City, Georgia, and have since returned in May 2025, October 2025, December 2025, March 2026, and June 2026.
During each season, I opportunistically sample approximately 250 metamorphosed and 250 larval individuals, resulting in nearly 3,000 unique individuals sampled thus far across approximately 21 amphibian species, including both frogs and salamanders. I am documenting seasonal patterns in the prevalence and intensity of chytrid fungus, ranavirus, and amphibian perkinsea. To quantify these pathogens, I collect swab, tissue, and blood samples from individual amphibians, as well as environmental samples through eDNA, which are analyzed using qPCR. I then compare pathogen loads and intensities to multiple biotic and abiotic factors, including seasonal climate, community composition, and overall host condition.
The Chattahoochee and Nantahala National Forests lie within what I consider to be one of the most beautiful places on Earth: the Blue Ridge Mountains. Because of their regional location, these mountains support forests characterized as temperate deciduous rainforests. The region experiences relatively few extreme temperature events, is dominated by deciduous vegetation, and receives substantial rainfall throughout the year. The combination of abundant water, moderate temperatures, and consistent seasonal change has created some of the most ideal amphibian habitats in North America. It is this exceptional habitat that makes the region so biologically important, but it also makes understanding how disease behaves within it increasingly urgent.
Amphibians are particularly valuable for understanding ecosystem health because they serve as bioindicators, allowing us to estimate environmental quality through their health and population patterns. At the same time, they are a central component of the food web, consuming insects such as mosquitoes while serving as prey for predators such as water snakes. Their ecological importance makes changes in amphibian health meaningful far beyond the individual animals themselves.
However, amphibians are also uniquely vulnerable to environmental change. As ectotherms, they rely on environmental temperatures to maintain body temperature and regulate critical physiological processes. Their immune systems are therefore strongly influenced by the environments in which they live. Different amphibian species possess relatively narrow and varied critical minimum and maximum temperatures that define the conditions under which they can function effectively. The pathogens I study also have specific functional temperature ranges, but their broader environmental tolerances can allow them to remain active and virulent under conditions in which amphibian immune function may already be compromised. As climate change continues to push ecosystems toward increasingly extreme and unpredictable temperatures, this mismatch between host and pathogen physiology is particularly concerning.
My research has given me the gift of witnessing and living among a large portion of the incredible amphibian diversity of the Blue Ridge Mountains, which supports more than 50 amphibian species. During each sampling season, I spend approximately a week intimately surveying not only amphibians for disease, but the greater ecosystem and its changing biodiversity. Each season feels like its own ecosystem. Familiar landscapes can become nearly unrecognizable as plants, animals, insects, water levels, and amphibian communities change throughout the year.
Summer is lush and dense, with vegetation covering the forest and wildlife seemingly everywhere. Most importantly for my research, amphibians become explosively abundant, with more than 17 species typically encountered. Insects, snakes, and turtles are also abundant, creating an ecosystem alive with movement. In fall, the forest begins to slow. The air chills, sunlight becomes a reminder of a waning summer, and cold nights prepare the ecosystem for winter. Foliage changes color before falling, while insect and bird activity decreases. Amphibian diversity remains relatively high, with around 13 species encountered, but the community becomes quieter. Tadpole numbers decline as most complete metamorphosis, woodland and stream salamanders remain active on rainy nights, and tree frogs retreat for the year.
Winter transforms the forest almost completely. Plants lose their foliage, ponds freeze, insect and reptile activity nearly disappears, and amphibians become sparse. Earlier in the winter, warm rainy nights can still bring red salamanders, pickerel frogs, and green frogs out as they travel toward suitable overwintering ponds. When those conditions are absent, surveying requires breaking through pond ice, dipnetting deep into the mud, and searching through it for juvenile water frogs, tadpoles, and juvenile woodland salamanders. Winter typically produces only around seven amphibian species.
Then spring arrives with a sense of relief. Temperatures begin to rise, precipitation increases, and plant life returns. Flowers bloom, trees produce bright-green leaves, and insects seemingly come back to life. Warmth, rain, and abundant food signal the beginning of another amphibian breeding season, marked by wood frog eggs and the calls of spring peepers. However, spring 2026 provided a stark reminder of how unpredictable these seasonal transitions can be. An unusual, freak snow event occurred as wildlife was beginning to emerge from winter dormancy, bringing a sudden return to cold conditions. For amphibians, which are especially dependent on environmental temperature, this abrupt disturbance likely imposed additional physiological stress during an already demanding transition into their active season. Around 15 amphibian species are typically encountered during spring, making this disruption particularly important to consider when interpreting the environmental and disease conditions observed during my 2026 sampling.
These seasonal changes demonstrate why disease cannot be understood independently of the environment. The interactions between environment, hosts, and pathogens create a complex disease dynamic in which even small changes can have significant consequences for disease outcomes. As emerging infectious diseases continue to rise, climate change alters temperature, humidity, and precipitation, and ecosystem health continues to decline, documenting temporal disease dynamics in vulnerable amphibian communities is imperative.
By establishing how pathogen prevalence and intensity change across seasons and how those patterns correspond with host condition, community composition, and environmental conditions, my research can help identify when and where amphibians are most vulnerable to disease. Ultimately, highlighting current disease patterns may allow us to predict disease-driven loss events before they occur and develop more effective conservation strategies. My goal is not simply to document what is happening within these mountains, but to understand why it is happening so that we can better protect the amphibians, forests, and ecosystems that have protected and inspired me throughout my life.
