Format: ORAL

Slvia Castro1*, Živa Fier2, Mariana Castro1, Joo Loureiro1, Joana Costa3, Staa Simcic2, Adela Horvat2, Rafael Matos1, Hava Verbessem1, Finding Bermuda buttercup team, Peter Glasnovic2

1 Centre for Functional Ecology, Department of Life Sciences, University of Coimbra, Coimbra, Portugal 2 Department of Biodiversity, Faculty of Mathematics, Natural Sciences and Information Technologies, University of Primorska, Koper, Slovenia 3 Linking Landscape, Environment, Agriculture and Food Research Centre (LEAF), Instituto Superior de Agronomia, University of Lisbon, Lisbon, Portugal

Biological invasions provide ideal scenarios for investigating evolutionary changes within contemporary timescales. Following long-distance dispersal, exotic species face significant mate limitations, which can potentially lead to shifts toward uniparental reproduction. However, the interplay of multiple introductions and natural selection in novel environments can induce transformative changes in well-established populations. Bermuda buttercup (Oxalis pes-caprae L.) is a polyploid tristylous plant native to South Africa and invasive in Mediterranean regions worldwide. While its native populations bear diploids or tetraploids with three flower morphs, facilitating sexual reproduction, invaded ranges display a reduced diversity, predominantly composed of pentaploid short-styled morph reproducing asexually. Nevertheless, new ploidies and floral morphs have been discovered in western Mediterranean basin, introducing new reproductive and, consequently, evolutionary contexts. This study aims to quantify shifts in ploidy and floral morph composition of Bermuda buttercup across the entire Mediterranean basin, exploring their implications for invasive species reproduction and evolution of reproductive systems. Finding Bermuda buttercup team, comprising over 40 researchers and 12 countries, collected data on floral morph composition, ploidy and fitness variables in invasive populations across the Mediterranean basin. Ploidy was determined for the majority of populations using flow cytometry on fresh material, while selected populations underwent floral morphometric analyses and quantification of pollen loads. This extensive assessment unveils novel insights into the distribution of ploidy and floral morphs and two contrasting scenarios emerge after successful establishment in the Mediterranean basin: the transition to uniparental reprodyction through clonality due to mate limitation, and the re-establishment of sexuality driven by multiple introductions of compatible mates and/or the breakdown of tristylous polymorphism in pentaploid short-styled plants. These findings underscore the dynamic nature of invasion processes, highlighting that ecological and genetic constraints inherent to the invasion process can give rise to distinct reproductive strategies, ultimately shaping the likelihood of invasion success.