The tenebrionid beetles on 25 circum-Sicilian islands were studied to determine the influence of island geographical and landscape features on three main intercorrelated biogeographical patterns: (1) species richness, studied using species-area and species environment relationships, (2) species assemblage composition, investigated using Canonical Correspondence Analysis (CCA), and (3) inter-site faunal similarity, investigated using Canonical Correlation Analysis (CANCOR) applied to multidimensional scaling of inter-island faunal dissimilarities. Species richness was mostly influenced by island area and landscape heterogeneity (expressed using various indices of diversity based on land cover categories). When species identities were considered in the CCA, no substantial effect of landscape was detected. Current island isolation did not have a strong influence on species richness, but has a distinct effect in determining species assortments on the remotest islands. Historical influences of Pleistocene landbridge connections were not detectable in species richness relationships using geographical variables in species richness analyses or in assemblage gradients in the CCA, but emerged distinctly from inter-island similarities in the CANCOR. and Simone Fattorini.
The tenebrionid fauna of the Tuscan Islands (Central Italy) is well known and is an ideal system for studying the role of current and historical factors in determining the biogeographical patterns in a complex archipelago. Cluster analyses, species-area relationships and Mantel tests were used to investigate the influence of current geography and Pleistocene connections with the mainland on the structure of insular communities. Current biogeographical similarity patterns fit both Pleistocene and Recent geography, but marked effects of Pleistocene geography appeared when the influence of Recent geography was removed. Thus, in contrast to more mobile insects, such as butterflies and chrysidids, tenebrionid colonization is likely to have occurred via land-bridges when the islands were connected to the mainland in the Pleistocene. The relict distributions of organisms with poor mobility should be of great concern to conservationists, because depletion of island populations cannot be balanced by new immigrations from mainland populations. The continued influence of man on the Tuscan Islands has adversely affected the natural environment, however, man made habitats may also be colonized and exploited by tenebrionids.
We analyzed the abundance, distribution and niche overlap of species (Pianka's Ojk index) in tenebrionid beetle communities inhabiting different biotopes in Tyrrhenian and Adriatic sand dunes. The rank abundance distribution of the different species has the form of a geometric series in both communities as predicted by the niche preemption hypothesis for communities in harsh environments. Mean niche overlap values did not deviate significantly from null expectations, which indicates random interspecific interactions. These results, coupled with evidence of species habitat preferences, led us to conclude that the community organization of tenebrionid species inhabiting coastal dunes is determined more by habitat preferences than interspecific competition., Simone Fattorini, Davide Bergamaschi, Cristina Mantoni, Alicia T. R. Acosta, Andrea Di Giulio., and Obsahuje bibliografii