Format: ORAL

Hanna Thosteman1*, Katherine Eisen1,2 , Hampus Petrn1,3, Sotiria Boutsi1,4, Loretta Pace5, John M. Halley6, Consuelo de Moraes7, Mark C. Mescher8, James Buckley7,9, Magne Friberg1

1. Department of Biology, Lund University, Sölvegatan 37, 22362, Lund, Sweden 2. Department of Biology, Loyola Marymount University, California, United States of America 3. Department of Biology, Philipps-Universität Marburg, Germany 4. Department of Agriculture and Environment Harper Adams University, Newport, United Kingdom 5. Medicina Sanità Pubblica Scienze della Vita e dell' Ambiente, Università degli Studi dell'Aquila, L’Aquila, Italy 6. Department of Biological Applications, University of Ioannina, Greece. 7. Biocommunication group, Institute of Agricultural Sciences, ETH Zürich, Switzerland 8. Plant Ecology group, Institute of Integrative Biology, ETH Zürich, Switzerland 9. School of Biological and Marine Sciences, University of Plymouth, United Kingdom

One recent discovery is the presence of variation in floral scent among conspecific populations of plants involved in generalized pollination systems. Often, such variation is taken as evidence suggesting that the floral scent of different populations is moulded in different directions by pollinator mediated selection, due to e.g. variation in local pollinator communities. Pollinators are believed to drive the evolution of floral scent in several systems, and this theory can also be tested for Arabis alpina. However, one possibility is that floral scent may not be the target of selection and that pollinators are not the only agents shaping the evolution of the floral scent chemistry in this system. Many floral scent compounds share biosynthetic pathways with defence compounds. Thus, selection pressures that affect defence compounds could result in indirect selection on the floral scent compounds. Therefore, to determine if floral scent is free to evolve unrelated to other plant compounds it is important to investigate to what degree floral scent compounds are correlated to other plant compounds, especially those involved in plant defence. We extracted floral scent, constitutive foliar volatiles and glucosinolates from 23 populations of the perennial herb Arabis alpina. Thereby, we could assess the magnitude of interdependence among these compounds produced and emitted by different plant tissues. By comparing integration indices, we found that floral scent was largely non-correlated with plant defence compounds in this species, and the geographically variable floral scent variation is thus likely the target of locally divergent selection pressures.