![]() However, the primers differ in the efficacy with which they amplify the target groups 22. In order to detect a wide range of prey, a number of “universal” primers for prey DNA detection have been developed to date 14, 15, 16, 17, 18, 19, 20, 21. However, the results may be affected, for example, by the use of PCR primers, sequences filtering and clustering. Thanks to the slow metabolic rate of spiders compared to other invertebrates 8, 9, the natural diet (the realised trophic niche) might be reconstructed even several weeks after food intake using molecular methods 10.įor species with cryptic feeding behaviour, gut content analysis based on prey DNA may be very efficient at determining the realised trophic niche of a species 11, 12, 13. Alternatively, the level of specialisation can be deduced by comparing fundamental and realised trophic niches. The levels of specialisation vary and are closely linked to behavioural, morphological, and/or physiological adaptations 6 which can only be revealed by means of experimental approaches 7. hidden in the litter), thus it is not known whether and to what extent they are specialised on a certain prey. Trophic niche of stenophagous species has been little investigated because of largely cryptic feeding (i.e. Among these the majority of data exist for euryphagous species, i.e. Spiders are the most diversified and important terrestrial arthropod predators 3 but evidence of breadth of trophic niche is available only for less than 2% of species 4. ![]() Thus to understand breadth of realised trophic niche of a predator, data on the available prey, co-occurring predators and competitors as well as local conditions are necessary. The fundamental niche can only be measured experimentally, whereas the realised niche is inferred from field data where prey exploitation is determined by the spatial and temporal co-occurrence of predator and prey, inter- and intraspecific competition among predators, mutualism, etc. While the former trophic niche is wide as it includes all prey types that the predator is capable of exploiting, the latter is obviously narrower as it is limited by prey availability. This can be resolved by comparing the fundamental and realised niches. For example, specialised exploitation of a limited type of resources (or stenophagy) can be either due to local (ecological) or global specialisation 1, 2. To understand trophic interactions in ecological, evolutionary or conservation studies a reliable estimate of the trophic niche is essential. exornata is an ant-eating euryphagous predator catching mainly Myrmicinae ants. The results show that Callilepis species are ant-eating (specialised) stenophagous predators, catching mainly Formicinae ants, while N. exornata the fundamental niche was wider than realised niche. The realised trophic niche in Callilepis species was similar to its fundamental niche but in N. exornata included many different prey types. The fundamental trophic niche of Callilepis species included mainly ants, while that of N. ![]() The cut-off threshold for erroneous MOTUs was identified as 0.005% of the total number of valid sequences, at individual predator level it was 0.05%. The general invertebrate ZBJ primers were not appropriate for detecting ant DNA as they revealed very few prey types, therefore ant-specific primers were used. For the latter two PCR primer sets were used as these can affect the niche breadth estimates. Acceptance experiments were used to estimate fundamental trophic niches and molecular methods to estimate realised trophic niches. schuszteri, Nomisia exornata) with different levels of myrmecophagy. Here we investigated trophic niches in three closely-related spider species from the family Gnaphosidae ( Callilepis nocturna, C. To investigate whether stenophagy is only a result of a local specialisation both fundamental and realised trophic niches need to be estimated. ![]() The levels of stenophagy and ant-specialisation vary among such species. Among spiders, taxonomically the most diversified group of terrestrial predators, only a few species are stenophagous and feed on ants.
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