Counting On It

I'm Ailene MacPherson, and I'm a biologist here at the Biodiversity Research Centre. I use mathematics to understand how populations evolve, in particular, how hosts and parasites co-evolve.

Math is everywhere. It's in the movement of stars and planets, and modelled by Galileo and Copernicus to optimize their telescopes. It's in how we build buildings, construct your house, and helps make sure trains arrive on time. And of course, it's the basis of so many things studied here at UBC. For me, it tells me how populations evolve.

Every species shares in common the fact that they have parasites. You might be a buffalo in South Africa infected with rinderpest, a cow infected with tuberculosis, or a human infected with HIV. But you all have the same problem – you were infected by a pathogen. That pathogen has big consequences on whether you survive, and as a result influences how your population evolves over time.

One of the first steps in studying host-parasite co-evolution is figuring out which genes make one host more susceptible to infection. The most practical way for biologists to determine this is by collecting large data sets and finding statistical associations between which host genotypes are infected by which pathogen genotypes.

As a mathematician, I can help develop statistical models that take into account how host and parasite co-evolve with one another. For example, humans that carry the CCR5 gene are less susceptible to HIV infection. If we could find more genes like CCR5, we might be able to build better vaccines that help people avoid infection.


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