UNCORRECTED PROOF Original article Regional species richness of families and the distribution of abundance and rarity in a local community of forest Hymenoptera Werner Ulrich * ,1 Department of Animal Ecology, Nicolaus Copernicus University Torun ´, Gagarina 9, 87-100 Torun, Poland Received 30 September 2004; accepted 7 October 2004 Abstract Recent investigations about the relationship between the number of species of taxonomic lineages and regional patterns of species abundances gave indecisive results. Here, it is shown that mean densities of species, of a species rich community of forest Hymenoptera (673 species out of 25 families) were positively related to the number of European species per family. The fraction of abundant species per family declined and the fraction of rare species increased with species richness. Species rich families contained relatively more species, which were present in only one study year (occasional species), and relatively fewer species present during the whole study period (frequent species). © 2004 Published by Elsevier SAS. Keywords: Hymenoptera; Parasitoids; Community structure; Rarity; Species richness; Singletons; Ecological drift 1. Introduction The question of how evolutionary history influences the distribution and abundance of species at local and regional scales has recently gained much interest. A series of studies dealing with birds and mammals showed that vulnerability to extinction is not randomly distributed and that species poor lineages contain higher proportions of regionally rare spe- cies, which are potentially in danger of becoming extinct (Russel et al., 1998, Purvis et al., 2000a, 2000b). On the other hand, Schwartz and Simberloff (2001) reported an opposite trend for North American vascular plants. They found that species poor taxa contain fewer numbers of regionally rare species. All of these studies dealt with abundance or spatial distri- bution patterns at regional or continental scales and used regional or global rarity as a metric for estimating extinction probabilities. However, whether species richness of taxa in- fluences patterns of abundance and therefore of community structure at the local, ecosystem scale is largely unknown. Additionally, there is an obvious lack of analyses about groups others than vertebrata (Schwartz and Simberloff 2001). The present paper tries to fill this gap in our knowledge. A local community of forest Hymenoptera is used to infer whether regional species richness is related to patterns of local abundance. Hymenoptera are one of the largest arthro- pod taxa. In Europe, about 16,000 species in 80 families have been described so far (Ulrich, 1999a) and local habitats like forests contain more than 500 species (Hilpert, 1989, Ulrich, 1998). This extraordinary high local and regional species richness makes the group an ideal candidate for the study of the relation between species richness of lineages and local abundance patterns. 2. Methods The compilations of Ulrich (1999a, 1999b, 2001a) are used to infer species numbers of European Hymenopteran families and included the recent new estimate for the Ichneu- monidae of Horstmann (2002). In total, about 16,000 species of European Hymenoptera have been described (Ulrich, 2001a). However, the exact number of Hymenoptera is even for Europe still unknown and the percent of undescribed species may be up to 20% for some families of Microhy- menoptera (Ulrich 1999a, Horstmann 2002, personal com- * Corresponding author.Tel.: +48-56-611-4469. E-mail address: ulrichw@uni.torun.pl (W. Ulrich). 1 www.uni.torun.pl/~ulrichw. ARTICLE IN PRESS Acta Oecologica "" (2004) """-""" www.elsevier.com/locate/actoec 1146-609X/$ - see front matter © 2004 Published by Elsevier SAS. doi:10.1016/j.actao.2004.10.003 ACTOEC-148 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60