Format: ORAL

Živa Fier1*,Botjan Surina2, Manica Balant3, Peter Glasnovic1, Ivan Radosavljevic4,5, Nataa Fujs1, Slvia Castro6

1 Glagoljaška 8, 6000, Koper, Faculty of Mathematics, Natural Sciences and Information Technologies, University of Primorska, Slovenia 2 Lorenzov prolaz 1, Rijeka, Natural History Museum Rijeka, Croatia 3 Passeig del Migdia s.n., Parc de Montjuïc, 08038, Barcelona, Institut Botànic de Barcelona (IBB, CSIC–Ajuntament de Barcelona), Spain 4 Marulicev trg 9a, 10000, Zagreb, Division of Botany, Department of Biology, Faculty of Science, University of Zagreb, Croatia 5 Svetošimunska cesta 25, 10000, Zagreb, Centre of Excellence for Biodiversity and Molecular Plant Breeding, Croatia 6 Calçada Martim de Freitas, 3000-456, Coimbra, Centre for Functional Ecology–Science for People & the Planet, Department of Life Sciences, University of Coimbra, Portugal

The mating system plays a crucial role in shaping the genetic structures within and between plant populations. In this study we present Moehringia tommasinii (Caryophyllaceae), a chasmophytic plant species with a limited range in the northwestern Adriatic region. Our research focused on examining the population biology of the species by studying all five extant populations. Additionally, we included populations of the co-occurring and much more widely distributed M. muscosa, a closely related species with distinct ecological characteristics. To investigate mating patterns, we conducted reciprocal crosses within and between these two taxa. Molecular markers were also utilized to estimate gene flow within populations and between taxa. Our investigation considered various factors, such as the coefficient of inbreeding, population size, seed weight, pollen-to-ovule ratio, flower display size, and the presence of a selfing syndrome. Contrary to our expectations, a high variation in mating systems was observed among populations of M. tommasinii. These populations demonstrated genetic structuring, with population size positively correlated with both seed weight and pollen production. Although a selfing syndrome could not be confirmed due to the majority of selfing resulting from allogamous treatments, the occurrence of selfing was notable. In the presence of M. muscosa, particularly in a closely coexisting site, a distinct pattern of fruit production was observed in M. tommasinii following various pollination treatments. Molecular and morphometric data provided evidence of hybridization followed by local extinction at this site. Population size emerged as the key factor influencing the mating system in genetically structured populations of M. tommasinii. While populations with higher selfing rates exhibited lighter seeds and reduced pollen production, these traits did not conclusively indicate the presence of a selfing syndrome. The detection of gene flow between M. tommasinii and sympatric M. muscosa suggested weak reproductive barriers between these taxa, potentially posing conservation challenges.