Format: ORAL

R. Sanchez1, MA. Ortiz2, F. Hortas3, L. Tomasson4, E. Serro5, K. Tremetsberger6, C. van Leeuwen7, A. Lovas-Kiss8, C. Reynolds9, J. Rowntree10and A. Green1.

1 Department of Conservation Biology and Global Change, Doñana Biological Station (EBD-CSIC), Spain 2 Department of Plant Biology and Ecology, University of Sevilla, Spain 3 Department of Biology, University of Cádiz, Spain 4 Department of Ecology, Swedish University of Agricultural Sciences, Sweden 5 Center for Marine Sciences, University of Algarve, Faro, Portugal 6 Institute of Botany (BOT), University of Natural Resources and Life Sciences, Vienna, Austria 7 Netherlands Institute of Ecology (NIOO-KNAW), Wageningen, Netherlands 8 Wetland Ecology Research Group, Centre for Ecological Research, Institute of Aquatic Ecology, Debrecen, Hungary 9 School of Animal, Plant and Environmental Sciences (APES),University of the Witwatersrand, Johannesburg, South Africa 10 School of Biological and Marine Sciences, University of Plymouth, Plymouth, UK

There is increasing evidence that migratory waterbirds act as important long-distance vectors of plants lacking a fleshy fruit. Seeds of many plants have been extracted from faeces and shown to have high germinability. However, there are almost no genetic studies addressing the influence of waterbird endozoochory on gene flow. Waterbirds can provide a means of spread across landscapes for alien species that were originally moved between continents by other means. We selected the buttonweed Cotula coronopifolia, native to South Africa, as our alien model species. This species was originally introduced to Europe more than two centuries ago, and has an extensive range. Faecal analysis confirmed endozoochory of this plant by migratory shorebirds such as Limosa limosa. Cotula coronopifolia is mainly distributed in coastal areas and is currently expanding along the Baltic coast. It is also spreading to inland wetlands with waterbirds, especially in Sweden and the UK. We are therefore studying the population structure and gene flow of 32 different populations of Cotula coronopifolia sampled in 6 European countries (UK, Germany, Netherlands, Spain, Sweden and Portugal), plus 5 populations in the native South Africa. We are using SNPs (Single Nucleotide Polimorfism) obtained from 282 individuals of Cotula coronopifolia by GBS (Genotyping by Sequencing). Questions we address include: 1) Are patterns across Europe consistent with the position of waterbird flyways? 2) Are patterns within a given landscape more consistent with dispersal by waterbirds, hydrochory, or human vectors? (i.e. are genetic distances more related to connectivity by birds, by water, or by human activities?). 3) within populations, are genetic distances determined by physical distances between plants? 4) are populations in the introduced range less diverse that those in the native range? Or has high propagule pressure (e.g. from multiple introductions via ballast from ships coming from South Africa) created the opposite effect?