Qiang Yang1, Anke Stein1, Patrick Weigelt2, Hanno Seebens3, Marten Winter4, Christian König2, Wayne Dawson5, Stefan Dullinger6, Franz Essl6, Trevor Fristoe1, Holger Kreft2, Bernd Lenzner6, Noëlie Maurel1, Dietmar Moser6, Jan Pergl7, Petr Pyšek7 and Mark van Kleunen1,8
1Department of Biology, University of Konstanz, Martin-Schleyer-Straße 36, 78465 Konstanz, Germany
2Biodiversity, Macroecology & Biogeography, University of Göttingen, Germany
3Senckenberg Biodiversity and Climate Research Centre, Germany
4German Centre for Integrative Biodiversity Research, Germany
5Department of Biosciences, Durham University, UK
6Division of Conservation Biology, Vegetation and Landscape Ecology, University of Vienna, Austria
7Institute of Botany, Department of Invasive Ecology, The Czech Academy of Sciences, Czech Republic
8Zhejiang Provincial Key Laboratory of Plant Evolutionary Ecology and Conservation, Taizhou University, China
Human activities and the consequent extirpations of native species and introductions of non-native species have largely modified the composition of species assemblages throughout the world (Winter et al. 2009, Villéger et al. 2014). These anthropogenic impacts have not only changed the richness of regional assemblages but also reduced the taxonomic dissimilarity among them, leading to the homogenization of many taxonomic groups across regions (Lockwood & McKinney 2001, Villéger et al. 2014). Moreover, Darwin’s naturalization hypothesis predicts that invaders less related to native flora are more likely to be successful than those closely related to natives (Darwin 1859), implying that the addition of naturalized species to a regional flora from more distantly related clades would also increase the evolutionary similarity between regional floras. While some work has been conducted assessing biotic homogenization at the national level, the extent of homogenization of the global flora, especially its phylogenetic component, has rarely been explored (Winter et al. 2009).
Using inventories of native species from the database GIFT (Global Inventory of Floras and Traits; Weigelt et al. 2019) and records of naturalized species from the GloNAF database (Global Naturalized Alien Flora; van Kleunen et al. 2018), we estimate to what extent naturalized species contribute to the taxonomic and phylogenetic homogenization of flowering plants between global regions. To have a comprehensive understanding of the main drivers of homogenization, we further assess how the relative changes in the taxonomic and phylogenetic dissimilarity between global regions relate to biogeographical and macroeconomic factors. We pay special attention to drivers that are most likely to determine the species introduction and establishment rate, including geographic connectivity, climatic and landscape similarity, bilateral trade, human migration, and the colonial relation between global regions.
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