Discriminating Between Microbial Populations

• Activity Number: 121
• Type: Topic Contributed
• Date/Time: Monday, August 2, 2010 : 8:30 AM to 10:20 AM
• Sponsor: Section on Bayesian Statistical Science
• Author(s): Frederick A. Matsen*+ and Steven N. Evans
• Companies: Fred Hutchinson Cancer Research Center and University of California, Berkeley
• Keywords: metagenomics ; optimal transport ; phylogenetics ; Wasserstein metric

Abstract

Metagenomics studies the collection of genetic material present in a community of microorganisms in a given environment. This enterprise is made possible by technologies that sequence a "soup" of DNA fragments sampled in bulk. Statistical methods can be used to assign these fragments onto a "reference" phylogenetic tree of previously identified species; each metagenomic sample thus results in a cloud of points on the reference tree. One is therefore led to consider statistical methods for distinguishing between such clouds. I will discuss work with Steve Evans (UCB) in this area in which we show that a very popular method intuited by microbial ecologists is actually one form of a distance between probability measures rooted in 18th century mathematics; I will then describe how this broader statistical view leads to generalizations and an understanding of the limiting distribution.