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Universidade de Coimbra (2020)

Invasive species - ecological and genomic approaches towards understanding local adaptation and early stages of allopatric speciation

Irimia, Ramona-Elena

Titre : Invasive species - ecological and genomic approaches towards understanding local adaptation and early stages of allopatric speciation

Espécies invasoras - abordagens ecológicas e genômicas para compreender a adaptação local e os estágios iniciais da especiação alopátrica

Auteur : Irimia, Ramona-Elena

Université de soutenance : Universidade de Coimbra

Grade : Doutoramento em Biociência, especialização em Ecologia, 2020

Résumé partiel
Invasive species are a threat to biodiversity and economy, and extremely challenging to eradicate once established. Much research in invasion ecology had focused on understanding the factors behind invaders’ success in new environments relative to the native range, formulate invasion theories, predict species abundance and occurrence, and provide management solutions. Nowadays, the new advancements in genomic tools and sequencing technologies make possible to disentangle some of the underlying evolutionary processes of trait divergence and rapid adaptation characterizing species introduction and invasion in new habitats. The aim of this thesis was to explore the ecological and genomic basis of rapid adaptation and evolution in the invasive annual forb Centaurea solstitialis (yellow star-thistle), across its worldwide distribution, including sites in the native range (Turkey and Spain) and introduced range (Argentina, Chile, USA and Australia). The thesis focuses on four main directions : i) assessing the role of polyploidy and genome size on species success ; ii) testing the allelopathic potential of leaf leachates iii) screening for reproductive isolation in allopatric populations, and iv) evaluating the adaptive phenotypic and genomic potential of introduced populations. In the introduction, I developed a brief systematic review by compiling information on the studies published in Centaurea solstitialis and indexed in the Web of Science during the past 70 years, to assess the current state of knowledge in this species. I identified a number of 365 relevant papers mostly with an ecological focus and having USA as the geographical region of the study. In the first chapter, I used flow cytometry to test the hypothesis that variation in genome size and changes in ploidy levels promote C. solstitialis invasion in the introduced range. I found no shifts in cytotype and similar genome size across native and non-native ranges, excluding the contribution of these factors to species invasiveness. Chapter II explored biogeographical variation in leaf allelochemical production and its effects on phytometer species between the two ranges, using three different leaf extract concentrations (0.25%, 0.5% and 0.75%) and germination bioassays tests.

Mots clés  : invasive species ; polyploidization ; allelopathy ; reproductive isolation ; speciation ; population genetics ; divergent selection ; espécies invasoras ; poliploidização ; alelopatia ; isolamento reprodutivo ; especiação ; genética populacional ; seleção divergente

Présentation

Page publiée le 22 mars 2021