Evolution of gene duplications and X/autosome
differences
Duplicated genes are a ubiquitous feature of eukaryotic
genomes. The availability of complete genome sequences has
reinvigorated evolutionary studies of gene families, in
part by facilitating the discovery of species-specific
duplication events and population-genetic studies of gene
families. A major controversy in the field is understanding
why duplicate loci are maintained in genomes--i.e. do they
provide new or specialized functions? Or are neutral
processes (such as subfunctionalization) a sufficient
explanation for the prevalence of duplicate loci?
Our work on duplicate genes in Drosophila melanogaster has
shown that gene families evolve very differently on the X
chromosome and the autosomes (Betran et al. 2002, Genome
Research; Thornton and Long 2002, 2005 MBE). The X/autosome
differences do not seem to be attributable to the dominance
or recessivity of adaptive substitutions (Thornton et al.
2006, Genome Research). The major empirical efforts in the
lab are focused on studying the population genetics of
duplicate loci in Drosophila melanogaster and other fruit
fly species (Thornton and Long 2002, 2005 MBE). The works
is interdisciplinary in nature, combining molecular
techniques with simulation and statistical methods to make
inferences about the evolutionary history of gene families.
Population genetics of
Drosophila
Much of our work involves analysis of population-genetic
data obtained from natural populations. These data provide
valuable insight into the adaptive and demographic
histories of natural populations (Haddril et al. 2005,
Genome Research; Thornton and Andolfatto 2006, Genetics;
Thornton and Jensen 2007, Genetics). Our research involves
the development and evaluation of methods to detect
adaptive evolution from variation data.