Species richness and phylogenetic structure of 249 global islands

To study how the phylogenetic composition of native island floras influences naturalized alien species richness, we assembled a dataset of 249 global islands from the global inventory of floras and traits (GIFT, Weigelt et al., 2020) and the Global Naturalized Alien Flora database (GloNAF, van Kleunen et al. 2019). The dataset contains naturalized and native species number, island area (km²) geological information from these sources. Additionally, we calculated three phylogenetic community metrics (Faith's PD, MPD and MNTD) using a global seed plant phylogeny (Smith and Brown, 2018) with different source pools, unstandardized Faith's PD with global island species pool, global island and mainland species pool and without missing species added to the phylogeny (pd, pd.matched), standardized measures with global island species pool and missing species added into the phylogeny (pd.ses, mpd.ses, mntd.ses), standardized measures with global island and mainland species pool and missing species added into the phylogeny (pd.ses.all, mpd.ses.all, mntd.ses.all) and standardized measures with global island species pool and missing species added into the phylogeny (pd.ses.matched, mpd.ses.matched, mntd.ses.matched). We also included biogeographical and socio-economical variables for the islands: mean annual precipitation (mm) and temperature (°C) (Karger et al., 2017), distance to closest mainland in km (Weigelt and Kreft 2013 and Moser et al., 2018) and terrain ruggedness index (Riley et al., 1999, USGS 2011). Finally, we included gross domestic product and number of ports (World Port index 2019) and airports (Open Flights 2015).