Phylogenetics Workshop -Abstracts
From Santa Fe Institute Events Wiki
Andrew Rambaut, University of Edinburgh
The Genomic and Epidemiological Dynamics of Human Influenza A Virus
"Influenza is one of the most common, and serious, respiratory infections of humans, with 3 to 5 million cases occurring annually worldwide, resulting in 250,000 to 500,000 deaths. Of the three types of influenza virus, those assigned to type A are the most virulent, and are associated with seasonal (winter) epidemics in temperate regions, year long transmission in the tropics, and occasional large-scale global pandemics that are characterized by substantial increases in morbidity and mortality. Whilst the adaptive interaction between the haemagglutinin (HA) protein of influenza A virus and the host immune system, ‘antigenic drift’, is one of the best described patterns in molecular evolution, studies have largely focused on the HA in isolation. Little attention has been paid to evolutionary dynamics at the genomic level, particularly the relationship between natural selection, reassortment, and the functional interactions among segments. We discuss the development and application of new phylogenetic techniques to analyse genomic sequences of IVA sampled globally over time. The aim is to investigate the rate of molecular evolution, the degree of selection acting on the genomic segments, the interactions between the segments and the rate of genetic exchange through the processes of reassortment and to characterize the relative importance of these forces to the evolutionary dynamics of this important human virus."
Hirohisa Kishino, University of Tokyo
Mike Steel, University of Canterbury
Phylogenetics: Interactions Between Mathematics and Evolution
This talk provides an overview of phylogenetics, and the mathematics behind it. I will focus on how combinatorics and probability theory can help address fundamental questions in evolutionary systematics -- from how much data is required to resolve a divergence in the distant past, to quantifying future biodiversity given current high rates of extinction.
"Variation of rates among sites: a problem for distance matrix methods?"
Distance matrix methods can adapt to rate variation among sites by allowing for it in the calculation of the distances. This allows for the variation in each distance. But it does not carry over the information from one pair to another about which sites are the ones with the highest rates of evolution. Likelihood (and Bayesian) methods do carry over this information properly. We would therefore expect distance methods to seriously lose power when compared to likelihood methods, as the amount of variation of rates among sites becomes greater. A small simulation study is under way, and by the time of this workshop we should know whether this expectation is met.