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Guillaume Louvel

Phd Student

Ecole Normale Supérieure
46 rue d’Ulm
75005 Paris, France
Tél : +33 (0)1 44 32 23 73

Subject :

Genomic markers of species diversification in vertebrates

Interests :

Several scales of evolutionary processes interest me ; at the genomic scale,
selection, on organisms or on "selfish" elements, and drift are processes that
are at the basis of the emergence of organismal diversity. These genomic
evolution is as well the result of individual- and population- (community, etc)
level processes, and trying understand this interplay is a very fascinating task
I would really like to work on. Currently, my PhD project addresses a part of
this picture, in vertebrates, focusing on the impact of gene duplication on
species diversification.

PhD project :

There are currently several hypotheses on the mechanisms of species divergence,
from genomic incompatibilities to divergent selection pressures. Given the
current availability of annotated full genomes for many non-model organisms
sampling various branches of the vertebrate phylogenetic tree, it becomes
possible to combine this genomic data with the patterns of speciation brought
by the analysis of complete phylogenies. Our work tries to implement this
general overview of how genomic features are implied in species
diversification. We first focus on gene duplications, mapping them on the
species phylogenetic trees by different functional categories. We also tried to
date each duplication more precisely using dS (synonymous substitution rate)
calculations, in order to obtain a finer estimation of the rate of gene
duplication through time and lineages. As the estimated rates seem to show,
this first method is sensitive to multiple factors (fast evolving branches,
quality of gene alignments, etc) making it quite imprecise. We are currently
working on improving these dating method, and aim towards more sophisticated
models of gene evolution that could estimate duplication ages (either adapting
existing models or developping one). Our broader aim is to compare the
duplication rates with diversification rates of taxons, and to question,
quantify the role of gene duplication in evolution.