Time and the environment are what drives evolution. On the molecular scale, evolution relies on genes and the changes that occur in them, giving rise to novel characters – or phenotypes. Evolution can even be sex-biased: i.e. certain genes may face different evolutionary pressures in males and females. In this respect, Robert Waterhouse, SIB Group Leader at the Department of Ecology and Evolution at the University of Lausanne, and his team discovered that a set of genes in mosquitoes does not seem to evolve in the same way it does in other insects, and perhaps even in many other organisms too.

Mosquito gender en website

When they set out to study arthropods, however, it was less to unveil the differences in the ways they evolve than to understand the underlying dynamics that govern the link between gene evolution and gene function (or phenotype). Grasping this link not only helps to predict the success of an insect’s outcome with respect to its environment for example, but can also provide researchers with the basis for developing tools for arthropod control and conservation.

“It’s all in the hyphen,” says Robert Waterhouse, referring to the title of his October seminar: Evolutionary-functional genomics for arthropod characterization, control and conservation. “The research we do focusses on the link between gene evolution and gene function, he continues, and how we can use information to fine-tune our understanding of it.” How better to find out than to study arthropods – such as the fruit fly Drosophila or the mosquito Anopheles – which, through the ages and thanks to advantageous mutations, have invaded every possible niche imaginable.

Previous studies on Drosophila showed that genes that are specifically or highly expressed in the male flies seem to evolve more rapidly than in their female-biased counterparts. “The same sort of trend seems to occur in birds too, adds Waterhouse, so things were looking straightforward enough.” Until the team turned their attention to mosquitoes – where they observed the opposite pattern of sequence and gene turnover evolution: i.e. genes with female-biased expression patterns evolve faster than male-biased genes. “Mosquitoes do it backwards,” smiles Waterhouse. “It could be that interactions with the host are driving the rapid evolution of genes important for female-specific biology”, he explains. Remember: only female mosquitoes bite. “These mosquitoes also only mate once, which doesn’t give much scope for male-male competition seen in many other species. As a result, pressures driving the evolution of genes important for male-specific biology may be weaker in mosquitoes.”

Where is this knowledge taking the team? Though still in its infancy, Waterhouse and his colleagues are working on the concept of evolutionary and functional maps to explore how gene evolutionary dynamics relate to the incredible phenotypic diversity of arthropods. “It is still very much of a concept, says Waterhouse. We need to experiment more with the available genomics data, and expand the information to build better maps. We then need to extend the concept to other groups of species.”

Robert Waterhouse is currently Assistant Professor at the Evolutionary-Functional Genomics Group of the Department of Ecology and Evolution, at the University of Lausanne.
After earning his PhD on comparative genomic analysis of disease-vector mosquitoes and insect immunity at the Imperial College of London (UK) in 2009, Waterhouse pursued his career at the Centre médical universitaire (CMU) de Genève and SIB. In 2013, he left for the Massachusetts Institute of Technology and the Broad Institute of MIT & Harvard before returning, two years later, to the University of Geneva and SIB. In 2016, he became Maître Assistant at the University of Geneva, and was appointed Assistant Professor at the University of Lausanne, where he is today, in 2018.

Reference:

Papa F et al. Rapid evolution of female-biased genes among four species of Anopheles malaria mosquitoes. Genome Research 2017. DOI: