Biogeography and ecology of endemic invertebrate species in Austria: A cross-taxon analysis

Abstract

Austria supports a considerable number of endemic invertebrate species, but a cross-taxon analysis is currently lacking. Based on a recent national inventory, we analysed distribution patterns, ecology and conservation biogeography of 361 endemic species and subspecies (beetles: 174taxa; butterflies and moths: 34taxa; caddisflies: 16taxa; snails: 80taxa; spiders and harvestmen: 57taxa) within Austria. Endemic species were very unevenly distributed with highest numbers of endemic species found in the North-eastern Calcareous Alps followed by the Southern Alps and the easternmost Central Alps. The location of hot spots (=grid cells of c. 35km2 size with highest endemic species numbers) varied substantially between taxonomic groups. The range size of endemic invertebrate taxa was skewed towards very narrow distributions – 222taxa are restricted to <10grid cells (total area c. 350km2), of which 71taxa were known from a single grid cell only. Between taxonomic groups we found substantial differences in elevation distribution. Whereas beetles and butterflies and moths were most species-rich at high elevations (1900–2000m a.s.l.), caddisflies (1000–1200m) and snails (400–500m) were most species-rich at mid to low elevations. Endemics associated with different broad habitat types differed markedly in average range size, endemics of habitats with limited and patchy distribution (caves, springs) had the smallest ranges. The endemic taxa of the five groups showed substantial differences in their habitat association. We found a strong positive correlation of range size with elevation range, whereas the number of habitats colonized was only weakly associated with range size. Thus, different features of niche breadth differed in their correlation with endemic species range sizes. Finally, we found that the conservation status of Austrian endemics is poor since 54% of the endemic species are nationally red-listed. Thus, a dedicated conservation strategy is urgently needed to conserve the endemic fauna of Austria.