UBC Math-Bio Seminar: Yexuan Song

Phylogenetic analysis is important for understanding the evolutionary relationships among taxa and is widely applied in epidemiology, evolutionary biology, and conservation. Despite many advances and theories developed, challenges and methodological developments remain necessary to address questions to inform public health decisions and conservation strategies. My talk addresses two such challenges.

First, I will introduce Sampling-Aware Ancestral State Inference (SAASI), a new ancestral state reconstruction method which accounts for uneven sampling between species/locations. I apply SAASI to the multi-host spread of the H5N1 virus in the United States in 2024 and find that the key transmission event from wild birds to cattle is estimated to occur later, with lower sampling in wild birds (compared to other species), than when sampling is not accounted for.

Second, I will consider the distribution of clade sizes under the coalescent model. I will describe how to calculate the probability of observing a particular clade size at a given time.