Native, alien, endemic, threatened, and extinct species diversity in European countries

While species diversity patterns at large scales (continental to global) have been increasingly studied recently for a few well-known taxa, only a few studies have included less well-known groups, and analysed congruence patterns between taxa. By using data from nine taxonomic groups (vascular plants, bryophytes, mammals, birds, reptiles, freshwater fish, amphibians, butterflies, dragonflies) from 38 European countries and Israel, we analysed the diversity of five diversity subsets (numbers of native, endemic, threatened, extinct, alien species) and their cross-taxon species diversity congruency. Native species numbers, and particularly, endemic species numbers are highest in large south European countries (Spain, Italy, Greece). The highest numbers of species being currently nationally threatened are located in industrialized Central European countries, whereas the highest numbers of nationally extinct species are found in Israel, Luxembourg, and Belgium. Established alien species numbers are highest in large western and (south)western European countries (United Kingdom, Spain, Italy, France). Across all taxonomic groups, the average proportion of endemic species of total native species numbers is 3%, of threatened species it is 27%, of extinct species it is 2%, whereas established alien species make up on average 11% of native species numbers. Highest proportions of endemic species were found in fish, grasshoppers, and reptiles, of threatened species in reptiles, amphibians and dragonflies, of extinct species in fish, dragonflies and grasshoppers, and of established alien species in fish, mammals and amphibians. Pairwise cross-taxon correlations of species diversity were pronounced for native species and endemic species, whereas correlations are much weaker for threatened, extinct and alien species numbers. Species-area relationships were significant but relatively weak for numbers of native and established alien species, whereas not significant for the other diversity subsets.. This study provides an important baseline assessment for a better understanding of European species diversity patterns. Future research avenues should aim at identifying causal relationships, and test for the effects of scale, life history and ecology of different taxa. Such an extended causal analysis should include historical effects, i.e. regional differences in rates of speciation, dispersal and extinction but also short-term fluctuations in human impact on species diversity, which are notoriously difficult to quantify, but frequently shape current diversity patterns. (C) 2013 Elsevier Ltd. All rights reserved.