Format: ORAL

Francisco Balao1, Jess Picazo-Aragons1, Alba Rodrguez-Parra1, Javier Lpez-Jurado1,Claudia Moreno-Portillo1, Stefan Dtterl2, Anass Terrab1

1 Department of Plant Biology & Ecology , University of Seville, Seville, Spain 2 Department of Environment & Biodiversity, Paris Lodron University Salzburg,Salzburg, Austria,

Polyploidy is a significant driver of plant speciation. However, the establishment of neo-polyploids requires a process of ecological divergence to alleviate inter-cytotypic competition. This divergence often encompasses quantitative and qualitative alterations in floral phenotype, potentially affecting pollination assemblage. This phenomenon holds notable significance within the intricate ecological context of the Mediterranean region, marked by its unique climatic nuances and a diverse array of ecological niches. Our objective is to elucidate the foundational mechanisms driving ecological divergence post-polyploidization, using the Mediterranean autopolyploid Dianthus broteri complex as a study system. This complex comprises four distinct ploidy levels (2x, 4x, 6x, and 12x) and parapatric monocytotypic populations along an arid gradient in the Iberian Peninsula. Through a multidisciplinary approach involving Reproductive Biology and Chemical Ecology, we identified alterations in the pollinator spectrum and analyzed changes in floral volatilome and transcriptome among cytotypes Our investigation identified varying floral scent profiles and distinct pollinator assemblages among cytotypes. The 12x cytotype, primarily pollinated by hawkmoths, exhibited floral scents rich in ketones, whereas the 2x and 4x cytotypes displayed high visitation rates by bees and floral scent composed by benzenoids, monoterpenoids and sesquiterpenoids. The 6x cytotype showed a floral scent enriched in sequiterpenoids and a generalist pollination by bees, butterflies, and moths. However, experimental sympatry of cytotypes suggested that complete isolation of cytotypes is not automatically conferred by pollinator shifts and may have required further evolutionary adaptations, such as habitat isolation, to diminish the immediate spatial overlap of the neo-polyploids. This comprehensive approach shed light on the mechanisms shaping evolutionary trajectories within the Dianthus broteri complex, providing valuable insights into the impact of autopolyploidy on plant speciation and adaptation.