Estimation of trophic niches in myrmecophagous spider predators

Among spiders, taxonomically the most diversified group of terrestrial predators, only a few species are stenophagous and feed on ants. The levels of stenophagy and ant-specialisation vary among such species. To investigate whether stenophagy is only a result of a local specialisation both fundamental and realised trophic niches need to be estimated. Here we investigated trophic niches in three closely-related spider species from the family Gnaphosidae (Callilepis nocturna, C. schuszteri, Nomisia exornata) with different levels of myrmecophagy. Acceptance experiments were used to estimate fundamental trophic niches and molecular methods to estimate realised trophic niches. For the latter two PCR primer sets were used as these can affect the niche breadth estimates. 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. 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 fundamental trophic niche of Callilepis species included mainly ants, while that of N. exornata included many different prey types. The realised trophic niche in Callilepis species was similar to its fundamental niche but in N. exornata the fundamental niche was wider than realised niche. The results show that Callilepis species are ant-eating (specialised) stenophagous predators, catching mainly Formicinae ants, while N. exornata is an ant-eating euryphagous predator catching mainly Myrmicinae ants

Photon-number distributions of twin beams generated in spontaneous parametric down-conversion and measured by an intensified CCD camera

The measurement of photon-number statistics of fields composed of photon pairs, generated in spontaneous parametric down-conversion and detected by an intensified CCD camera is described. Final quantum detection efficiencies, electronic noises, finite numbers of detector pixels, transverse intensity spatial profiles of the detected beams as well as losses of single photons from a pair are taken into account in a developed general theory of photon-number detection. The measured data provided by an iCCD camera with single-photon detection sensitivity are analyzed along the developed theory. Joint signal-idler photon-number distributions are recovered using the reconstruction method based on the principle of maximum likelihood. The range of applicability of the method is discussed. The reconstructed joint signal-idler photon-number distribution is compared with that obtained by a method that uses superposition of signal and noise and minimizes photoelectron entropy. Statistics of the reconstructed fields are identified to be multi-mode Gaussian. Elements of the measured as well as the reconstructed joint signal-idler photon-number distributions violate classical inequalities. Sub-shot-noise correlations in the difference of the signal and idler photon numbers as well as partial suppression of odd elements in the distribution of the sum of signal and idler photon numbers are observed.Comment: 14 pages, 14 figure

Silk versus venom: alternative capture strategies employed by closely related myrmecophagous spiders

Predators that prey on dangerous species have evolved effective capture traits. In spiders, venom and silk represent distinct substances associated with prey capture. However, the use of such adaptations comes at a cost. Based on a possible trade-off, the use of only one effective capture mechanism should be optimized if a predator is to specialize on a single type of dangerous prey. We investigated hunting strategies in two Callilepis spp. and one Nomisia species, Nomisia exornata, closely related ant-eating spiders from the family Gnaphosidae. We hypothesized that specialized Callilepis spiders would adopt a more stereotyped capture strategy compared with less specialized Nomisia. We also expected that Callilepis would rely on only one subjugation mechanism. To test this, we compared their hunting efficacy and hunting strategies, with an emphasis on venom vs. silk utilization. Nomisia restrained ants with silk (then bit them), whereas Callilepis relied solely on its venom. This was also reflected in trophic traits connected with silk and venom utilization; Callilepis had larger venom glands than Nomisia, whereas Nomisia had more piriform silk glands than Callilepis. Callilepis was more effective because it subdued prey more quickly, presumably owing to ant-specific venom. Callilepis and Nomisia handled ants from two subfamilies with different degrees of success; Callilepis was more successful with Formicinae ants, whereas Nomisia handled Myrmicinae ants better. We show that sole reliance on venom allows Callilepis to be more efficient in overcoming ants than Nomisia, which uses both silk and venom. However, such specific adaptations might restrict specialized predators from exploiting alternative prey

The World Spider Trait database: a centralized global open repository for curated data on spider traits

Spiders are a highly diversified group of arthropods and play an important role in terrestrial ecosystems as ubiquitous predators, which makes them a suitable group to test a variety of eco-evolutionary hypotheses. For this purpose, knowledge of a diverse range of species traits is required. Until now, data on spider traits have been scattered across thousands of publications produced for over two centuries and written in diverse languages. To facilitate access to such data, we developed an online database for archiving and accessing spider traits at a global scale. The database has been designed to accommodate a great variety of traits (e.g. ecological, behavioural and morphological) measured at individual, species or higher taxonomic levels. Records are accompanied by extensive metadata (e.g. location and method). The database is curated by an expert team, regularly updated and open to any user. A future goal of the growing database is to include all published and unpublished data on spider traits provided by experts worldwide and to facilitate broad cross-taxon assays in functional ecology and comparative biology.Fil: Pekár, Stano. Masaryk University; República ChecaFil: Wolff, Jonas O. University of Greifswald; AlemaniaFil: Cernecká, L'udmila. Slovak Academy of Sciences; ArgentinaFil: Birkhofer, Klaus. Brandenburgische Technische Universität Cottbus; AlemaniaFil: Mammola, Stefano. University of Helsinki; FinlandiaFil: Lowe, Elizabeth C.. Macquarie University; AustraliaFil: Fukushima, Caroline S.. University of Helsinki; FinlandiaFil: Herberstein, Marie E.. Macquarie University; AustraliaFil: Kucera, Adam. Masaryk University; República ChecaFil: Buzatto, Bruno A.. University of Western Australia; AustraliaFil: Djoudi, El Aziz. Brandenburgische Technische Universität Cottbus; AlemaniaFil: Domenech, Marc. Universidad de Barcelona; EspañaFil: Enciso, Alison Vanesa. Fundación Protectora Ambiental Planadas Tolima; ColombiaFil: Piñanez Espejo, Yolanda María Guadalupe. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Nordeste. Instituto de Biología Subtropical. Instituto de Biología Subtropical - Nodo Posadas | Universidad Nacional de Misiones. Instituto de Biología Subtropical. Instituto de Biología Subtropical - Nodo Posadas; ArgentinaFil: Febles, Sara. No especifíca;Fil: García, Luis F. Universidad de la República; UruguayFil: Gonçalves Souza, Thiago. Universidad Federal Rural Pernambuco; BrasilFil: Isaia, Marco. Università di Torino; ItaliaFil: Lafage, Denis. Universite de Rennes I; FranciaFil: Líznarová, Eva. Masaryk University; República ChecaFil: Macías Hernández, Nuria. Universidad de La Laguna; EspañaFil: Fiorini de Magalhaes, Ivan Luiz. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Museo Argentino de Ciencias Naturales "Bernardino Rivadavia"; ArgentinaFil: Malumbres Olarte, Jagoba. Universidade Dos Açores; PortugalFil: Michálek, Ondrej. Masaryk University; República ChecaFil: Michalik, Peter. ERNST MORITZ ARNDT UNIVERSITÄT GREIFSWALD (UG);Fil: Michalko, Radek. No especifíca;Fil: Milano, Filippo. Università di Torino; ItaliaFil: Munévar, Ana. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Nordeste. Instituto de Biología Subtropical. Instituto de Biología Subtropical - Nodo Puerto Iguazú | Universidad Nacional de Misiones. Instituto de Biología Subtropical. Instituto de Biología Subtropical - Nodo Puerto Iguazú; ArgentinaFil: Nentwig, Wolfgang. University of Bern; SuizaFil: Nicolosi, Giuseppe. Università di Torino; ItaliaFil: Painting, Christina J. No especifíca;Fil: Pétillon, Julien. Universite de Rennes I; FranciaFil: Piano, Elena. Università di Torino; ItaliaFil: Privet, Kaïna. Universite de Rennes I; FranciaFil: Ramirez, Martin Javier. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Museo Argentino de Ciencias Naturales "Bernardino Rivadavia"; ArgentinaFil: Ramos, Cândida. No especifíca;Fil: Rezác, Milan. No especifíca;Fil: Ridel, Aurélien. Universite de Rennes I; FranciaFil: Ruzicka, Vlastimil. No especifíca;Fil: Santos, Irene. No especifíca;Fil: Sentenská, Lenka. Masaryk University; República ChecaFil: Walker, Leilani. No especifíca;Fil: Wierucka, Kaja. Universitat Zurich; SuizaFil: Zurita, Gustavo Andres. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Nordeste. Instituto de Biología Subtropical. Instituto de Biología Subtropical - Nodo Posadas | Universidad Nacional de Misiones. Instituto de Biología Subtropical. Instituto de Biología Subtropical - Nodo Posadas; ArgentinaFil: Cardoso, Pedro. No especifíca

The World Spider Trait database : a centralised global open repository for curated data on spider traits

Publisher Copyright: © The Author(s) 2021. Published by Oxford University Press.Spiders are a highly diversified group of arthropods and play an important role in terrestrial ecosystems as ubiquitous predators, which makes them a suitable group to test a variety of eco-evolutionary hypotheses. For this purpose, knowledge of a diverse range of species traits is required. Until now, data on spider traits have been scattered across thousands of publications produced for over two centuries and written in diverse languages. To facilitate access to such data, we developed an online database for archiving and accessing spider traits at a global scale. The database has been designed to accommodate a great variety of traits (e.g. ecological, behavioural and morphological) measured at individual, species or higher taxonomic levels. Records are accompanied by extensive metadata (e.g. location and method). The database is curated by an expert team, regularly updated and open to any user. A future goal of the growing database is to include all published and unpublished data on spider traits provided by experts worldwide and to facilitate broad cross-taxon assays in functional ecology and comparative biology. Database URL:https://spidertraits.sci.muni.cz/.Peer reviewe

Generation of sub-Poissonian non-Gaussian states from multimode twin beams by photon-number-resolving detectors

We generate sub-Poissonian non-Gaussian conditional states from pulsed multimode twin beams (TWBs) by measuring with photon-number-resolving detectors. Links among twin-beam non-classicality and the properties of the conditional states are discussed