To develop his big idea, Charles Darwin measured and theorized about the beaks of finches stranded on a tiny speck of an island because it allowed him to see a clear marker of evolution in action.
Assistant Professor of Biology Katia Koelle studies the evolution of something incredibly numerous and too small to see -- the microbes that create devastating infectious diseases such as influenza, cholera, and dengue. But through them she is able to see Darwinian evolution in fast-forward and on a planetary scale.
To know why and how these infectious microbes constantly change their stripes is important because "we need to understand how these pathogens are evolving to be able to predict when and where disease outbreaks will arise and how large they'll be."
As a Stanford undergrad, Koelle bounced between philosophy, biology and economics before discovering what she calls the beauty of theoretical ecology under the tutelage of Joan Roughgarden. Using statistics and computer models, a biologist has "a way to formally, quantitatively, theorize about the factors driving evolution and affecting population sizes;" for example, why cholera epidemics in the Indian subcontinent aren't only seasonally variable, but differ in magnitude over longer periods of time.
Research with her doctoral adviser, Mercedes Pascual at the University of Michigan, showed that cholera epidemics are not only affected by seasonal factors, but also by more gradually changing components of climate. For example, the size of cholera outbreaks in Bangladesh in part depends on the periodic El Niño climate disturbance in the South Pacific on the other side of the world.
Infectious microbes, like all living things, respond in their genes and their population sizes to the dynamics of the environment they encounter. A changed environment means a changed microbe, with all that that entails for the human populations they afflict.
Seeing these patterns for what they are and knowing how they work will in turn lead to better prediction of future outbreaks and also better prevention strategies, Koelle says. (In the case of cholera, it also makes yet another frightening argument about the dangers of global climate change.)
She has recently turned from studying cholera to studying viral pathogens such as flu. The patterns of evolutionary change one sees in different viruses show striking similarities, Koelle explains in another breathless burst of words. When the numbers are crunched, they reveal a period of seemingly no change, followed by a rapid emergence of a more fit strain, a new version of the old menace.
"It's the exact same pattern across very different viruses," she says. "It's amazing."
Koelle's temporary office in the French Family Science Center is bare and empty except for several stacks of stapled journal articles on the desk and shelves. "This is my HIV stack," she says, pulling down a tottering pile of papers.
Like her science, Koelle is global in her upbringing. Born to European parents in Germany, she lived for several years in Japan as a young child, before moving to Westchester County, NY. She's starting to discover the mountain biking opportunities around the Triangle, and will be looking to buy a house in Durham soon.
With no teaching duties in her first term, she intends to connect with Duke ecologists and evolutionary biologists, as well as more applied medical researchers at the university. She has a five-year research plan in view, and the wicked RNA viruses, influenza and HIV, are squarely in her sights.