Diet compositions of the European polecat (Mustela putorius) and the stone marten (Martes foina) were studied through macroscopic and microscopic analyses of 69 polecat and 120 stone marten stomachs dissected between 2000 and 2006 in Southern Moravia (Czech Republic). The diets of both mustelid species included a wide variety of prey species but were dominated by mammals and birds. Frogs were consumed only in winter. No reptiles were found in the diet of either species. Invertebrates were rarely present in the polecat diet but very common in the stone marten diet. In summer, the most common food for the stone marten was fruit. The stone marten consumed significantly more rodent species, especially rats (Rattus norvegicus), and songbirds and the food niche of the stone marten was broader than that of the polecat. The trophic niche overlap of both species, based on Pianka’s index, was highest in winter. Stone martens appear to be an important food competitor of European polecats in the Czech Republic, mainly in winter when food resources are limited.
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
1_Insects feeding on the foliage of oak were studied on a mountain where species of Mediterranean deciduous and evergreen oak coexist. There were 58 insect species (54 Lepidoptera, 1 Coleopteran and 3 Hymenoptera) belonging to twenty families in the assemblage feeding on eight species of Quercus, two of which are introduced from nearby regions. The overlap in occurrence in time and of feeding niches of the insects feeding on the foliage of the different species of oak was determined using the: (a) Poole-Rathcke method, which tests phenological overlap and (b) Petraitis method, which tests niche overlap. This indicated that insect families partition seasonal time in a random and the entire assemblage in a regular way. All groups of insects partitioned season randomly except for the pairs of monophagous-oligophagous and Palearctic-Eurosiberian species, which partition season regularly. Oak folivorous insects correctly perceive the three subgenera of oaks with the exception of the planted Q. robur pedunculiflora. The folivorous insects recorded on the Mediterranean evergreen oaks (subgenus Sclerophyllodrys) differ from those on the other two subgenera (Quercus and Cerris) and co-occurring deciduous trees. The hypothesis of complete general overlap is rejected for groups based on feeding specialization, zoogeographical categories and taxonomic families. The same was the case when the entire insect assemblage was considered. The percentage of specific niche overlap of the folivorous insects is low and greatest among the monophagous species (13.8%) and those with a Mediterranean distribution (15.4%). Voltinism is not very important for this assemblage and only seven species are bivoltine of which four fed on a different species of oak in the second generation., 2_The overall conclusion is that the co-occurrence in space of these species is possible because they occur regularly at different times during the season whereas that of insect groups based on zoogeographical, taxonomic or feeding specialization are randomly dispersed in time., Maria Kalapanida, Panos V. Petrakis., and Obsahuje seznam literatury