Download Project description - Norwich Research Park

ELSA Project: How does sexual selection shape a genome?
PIs: Matt Gage (UEA), Saskia Hogenhout (JIC)
Pump Priming Funding round: May 2013
Background: Sexual selection, Darwin’s second great idea, is an evolutionary force that acts on
almost every species on earth involved in the struggle to sexually reproduce. In this ELSA project, we
will aim to understand how sexual selection acts on the genome. The big question we ultimately
plan to answer is whether sexual selection acts right across the genome (because all traits are
important for achieving reproduction: the ‘Genic Capture’ theory), or whether it acts just on
reproductive traits (Darwin’s theory), or indeed that it does not change the genome, but works via
differential expression. It is important to understand how sexual selection works, not just because it
concerns every species on earth, but also because we need to quantify the importance of this
process for maintaining the genetic health of populations under increasing environmental stress.
To answer this question experimentally, we have an excellent resource in replicate lines of the flour
beetle Tribolium castaneum (pictured), which have been evolving in the lab for more than 8 years
under experimentally controlled levels of either very high or very low sexual selection, creating adult
conditions that profoundly vary the levels of male-male competition and female choice for
reproduction. We already know that individuals within these populations have evolved and diverged
in important ways relating to reproduction, and that populations under high sexual selection appear
to have been more effectively purged of their mutational load. Because the Tribolium genome has
already been sequenced and is well annotated, we can now also resequence the genomes of these
experimentally-evolved populations, and compare how much, and where, the genomes have
changed under divergent intensities of sexual selection.
Core hypothesis: To test the Genic Capture theory: that populations evolving from a common
ancestor under sole variation in the intensity of sexual selection will show significant and widespread
genomic divergence.
ELSA project: With TGAC and the NERC Biomolecular Analysis Facilities, we aim to achieve 10x
coverage of the resequenced genomes from replicate individuals from our High and Low sexual
selection lines, comparing SNP changes to their ancestral Ga-1 population, and a control. Detailed
coverage of the published Tribolium genome is available at http://beetlebase.org, with bioinformatics focusing on measures of variance in SNP changes between lines versus between regimes.
Copulating Tribolium flour beetles:
after experimentally evolving
populations under sole variation in
sexual selection, this project will assess
the effect of sexual selection upon
genome evolution.