Pacific Institute for the Mathematical Sciences - PIMS

Lateral Gene Transfers, From a Phylogenetic Nightmare to a Phylogenetic Marker

Macromolecules (DNA, RNA, proteins) are long sequences
over small alphabets which contain informations about the functionning
of the carrier organisms as well as traces of their descent, the history
of individuals, populations, species, up to the deep history of life.

As every lineage records its own events, the comparison of molecules
with dedicated algorithms allows to decipher the information stored in
these chemical strings. This series of four lectures is devoted to some
of the mathematics and algorithms designed for analyzing molecular data
and their evolution.

In particular I will present some solutions to genomes rearrangement
problems. Thought historically rearrangements were the first mutations
discovered, they are poorly exploited in evolutionary biology compared
to sequence substitutions because of the combinatorial complexity of the
objects commonly used to model them. Solutions will consist in modeling
random walks in large discrete spaces, and determining shortest paths
or likely paths between a start and an end point of the walk.

Then I will talk about models for phylogeny, and in particular how
they cope with gene transfers, that is, the exchange of genetic material
between different species. Models of gene evolution with transfers can
help dating in the deep past of the living world, in the absence of
fossil reconrd.

Location: Simon Fraser University, Burnaby campus, room K9509.