Transposable elements driven adaptation to temperate environments in the Asian tiger mosquito Aedes albopictus – MosquiTEs

Understanding how species and populations adapt to new environmental conditions is one of the goal of evolutionary biology and has never been more important in the current context of both climate change that challenges every single species and globalization and the intensification of international trade that leads to the introduction of exotic species into new locations.
The NGS (Next Generation sequencing) revolution led to the production of population genomics datasets that made possible mapping the footprint of natural selection at a very fine resolution. Yet a major component of genomes is most often ignored in such studies : transposable elements (TEs).
TEs are repetitive sequences that populate the genome of every single species. These sequences are able to make copies of themselves through the transposition process. While the majority of new insertions are neutral or deleterious, some of them are beneficial to their host, and there are some spectacular examples of recent adaptation due to TEs, such as insecticide resistance in Drosophila, or the textbook example of industrial melanism in the peppered moth Biston betularia. While these examples suggest that TEs may be a particularly fecund substrate upon which selection can act to quickly lead to adaptation, there has been only a few systematic investigation of the role of TEs in adaptation in model species and none, to our knowledge, in invasive species.
Invasive species are a major threat to biodiversity and often for agriculture and Human health. Studying the mechanisms by which they thrive in new environments is necessary to predict the risk of success of newly introduced species but can also illuminate our understanding of adaptation in general. The Asian tiger mosquito Aedes albopictus is one such species. This mosquito is a vector of several arboviruses such as Dengue and Chikungunya viruses. From its original cradle in Asia it has spread to Europe, the Americas and Africa thanks to the trade of used tyres in the last 40 years.
One of the most conspicuous characteristics of this mosquito is the ability of temperate populations to produce cold-hardy diapausing eggs in response to shortening days to ensure winter survivorship. While this adaptive phenotype has probably been acquired during the colonization of Northern parts of Asia from tropical South-east Asia a few 10,000s years ago, there is evidence of rapid adaptive evolution of the photoperiod induced diapause in recently invaded areas such as the USA. Another remarkable aspect of this mosquito is that its genome is riddled with TEs (>60% in the Foshan strain reference genome) which may represent a huge reservoir to produce genetic variation.
The goal of this project is thus to determine what is the contribution of TEs to adaptation in the Asian tiger mosquito Aedes albopictus, with a special emphasis on its recent adaptation to temperate environments. This will be achieved first by detecting TE insertions that display the footprint of adaptation in the Aedes albopictus 1000 genomes project led by partner 2 and then by characterizing the molecular and macroscopic phenotypes conferred by these insertions.
This project is expected to lead to breakthroughs in our understanding of environmental adaptation and the contribution of TEs in this adaptation.