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Stéphanie SHERPA, winner of the 2020 Academic Thesis Award

is the winner of the Academic Thesis Award 2020 with 7 other PhDs for her thesis presented in 2019 and entitled "Colonization history and factors promoting the success of invading populations of the Asian tiger mosquito Aedes albopictus in Europe". The academic thesis prizes were awarded to eight Doctors using criteria of excellence specific to each discipline and represented by the 13 doctoral schools on site.
Winner of the 2020 Academic Thesis Award: Stéphanie SHERPA

Stéphanie SHERPA, lauréate du prix de thèse académique 2020Thesis title: Colonization history and factors promoting the success of invading populations of the Asian tiger mosquito Aedes albopictus in Europe

Doctoral school: ED CSV - Chemistry and Life Sciences

Host laboratory: Alpine Ecology Laboratory (LECA - CNRS / UGA / USMB)

Thesis supervisors: Laurence DESPRES and Michael BLUM

Key words: biological invasion, population genetics, landscape genetics, local adaptation, Aedes albopictus

The thesis focuses on the invasion of the tiger mosquito in Europe, first by reconstructing invasion routes in order to better understand the importance of the methods of introduction (number and origin of introductions) and adaptive processes (pre-adaptation in the native area, post-introduction adaptation in the invaded area) in the successful establishment of introduced populations. The thesis then studies the dynamics of expansion across the landscape. To do this, the thesis analyses the genetic and morphometric characteristics of invasive populations and their sources, and compares the environmental characteristics of the native and introduced areas based on the spatio-temporal detection data of the species.

Abstract
The Asian tiger mosquito, Aedes albopictus, is native to Southeast Asia and has colonized all continents but Antarctica in the last decades. However, the factors determining the invasive success of populations at the global scale remain to be elucidated. Focusing on the European invasion, we used a comprehensive framework and multi-source data for distinguishing the role of historical and contemporary processes, neutral and adaptive, in structuring the genetic variability of invasive populations. The genetic variability of 1,000 individuals from 150 invasive and native populations revealed three independent introduction events in Europe (in Albania, North Italy, and Central Italy), from the United States (previously invaded area) and from China (native range). Primary introduced populations constituted dispersal centers for the colonization of Europe, and migration routes correlate with the geography of human transportation networks. Several admixture events either during introduction or subsequent expansion, as well as high connectivity between invasive populations, promoted the maintenance of high levels of genetic diversity. Pre-existing cold adaptation within the native range of the species and niche conservatism between introduced populations and their sources suggest that these populations were already prepared for establishing under temperate European climate. Nonetheless, shifts in allele frequencies along environmental gradients within Europe suggest post-introduction adaptive changes. The adaptive potential of populations and long-distance human-aided dispersal facilitated the rapid expansion of populations. Although often neglected in the context of biological invasions, natural dispersal at the landscape scale further contributed to range filling in range edge populations. The study of the demo-genetic and environmental characteristics of the European invasion allows a better understanding of processes at play during two key stages of the invasion process: establishment and expansion.

> Discover all the winners of 2020 Thesis Awards


Updated on June 3, 2020

Relocation

The College and the doctoral schools (except Philo) moved on September 1st, 2020 to join the Maison Jean Kuntzmann at 110 rue de la Chimie 38400 Saint-Martin-d'Hères on the University Campus (Tram B and C, stops "Bibliothèques universitaires").
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