## PIMS- UVictoria Distinguished Lecture: Caroline Colijn

- Date: 10/24/2019
- Time: 15:20

University of Victoria

Trees, metrics, inference and transmission

Improvements in sequencing technology mean that we have rich data on how infections evolve and spread. In this talk I will describe two settings where this calls for new mathematics. Trees -- in the sense of graphs with no cycles -- are a cornerstone of how we understand these data. Trees can represent patterns of ancestry through time, showing evolutionary stories that are supported by data and revealing how consistent models are with data. In the first part of the talk, I will describe a metric on trees that is based on polynomial representations of trees. Since each tree has a unique polynomial, comparing the coefficients yields a suite of tree comparison tools. We illustrate these with data from cetacean evolution and infectious disease. In the second part of the talk, I will describe how we can use trees, together with a type of colouring, to do Bayesian inference of who infected whom in an infectious disease outbreak. I will apply this tool to data from tuberculosis infections.

**Speaker Biography** Caroline Colijn is a Professor & Canada 150 Chair in Mathematics for Infection Evolution and Public Health at SFU. Professor Colijn began her studies at the University of British Columbia in mathematics and physics. From there, she received her master’s degree in environmental studies at York University before continuing to a PhD in applied mathematics at the University of Waterloo. Her broad interests and academic background are a great fit for what she does now, which connects her to public health researchers, epidemiologists and biologists, as well as mathematicians and statisticians. In a nutshell, Caroline seeks to build mathematical and statistical tools to make the best possible use of the rich data available from sequencing technologies. The ultimate aim is to improve how we control infections.

Caroline’s work spans mathematics, statistics and data, and genomics and public health. The ability to gather genomic data in public health is outpacing our ability to interpret the data. By creating new tools there are exciting opportunities for mathematics-centered research to make strong contributions. Caroline’s research team has combined innovations from branching processes, discrete mathematics, computational biology and evolutionary theory to meet challenges in health and medicine.

Engineering/Computer Science 124

Tea reception 3-3:20pm

Academic Seminar 3:20-4:20pm