22,992 research outputs found
Annotated checklist of Georgian oribatid mites-II
No full textMurvanidze, Maka, Todria, Nino, Maraun, Mark, Mumladze, Levan (2023): Annotated checklist of Georgian oribatid mites-II. Zootaxa 5227 (1): 50-62, DOI: https://doi.org/10.11646/zootaxa.5227.1.
FIGURE 1 in New taxa and new records of oribatid mites of the family Galumnidae (Acari: Oribatida) from Ecuador
No full textFIGURE 1. Neoctenogalumna longiciliata sp. nov., adult: A—body dorsally; B—body ventrally (gnathosoma and legs not illustrated); C—prodorsum, pteromorph and anterior part of notogaster dorso-laterally; D—notogaster posteriorly. Scale bar 50 Μm.Published as part of Ermilov, Sergey G., Starý, Josef, Sandmann, Dorothee, Marian, Franca & Maraun, Mark, 2013, New taxa and new records of oribatid mites of the family Galumnidae (Acari: Oribatida) from Ecuador, pp. 259-270 in Zootaxa 3700 (2) on page 262, DOI: 10.11646/zootaxa.3700.2.4, http://zenodo.org/record/22012
Small-scale spatial heterogeneity of stable isotopes signatures (δ15N, δ13C) in Sphagnum sp. transfers to all trophic levels in oribatid mites
No full textSmall-scale heterogeneity is important for understanding soil animal diversity since it may explain their local coexistence. We investigated the heterogeneity within and between three Sphagnum microhabitats (Sphagnum lawn: apical green part, decomposing brown part; submerged Sphagnum) and the heterogeneity of potential consumers (oribatid mites) in two German peatlands (Dubringer Moor, Klockenbruch) using stable isotopes (N-15, C-13). Small-scale heterogeneity of the potential food resource (Sphagnum sp.) in N-15 and C-13 was high. The heterogeneity of N-15 signatures of Sphagnum sp. was transferred to oribatid mite taxa indicating that Sphagnum sp. is their basal food resource. The close relationship between stable isotopes ratios in Sphagnum sp. and oribatid mites on the scale of a few meters furthermore points to the low mobility of mites. When oribatid mites where aggregated into trophic levels, the strongest correlation occurred between N-15 in Sphagnum sp. and oribatid mites of the first trophic level. Oribatid mites spanned 9.1 delta N-15 and 4.4 delta C-13 units in the Dubringer Moor and 9.5 delta N-15 and 4.7 delta C-13 units in the Klockenbruch indicating that they span over about three trophic levels. Three oribatid mite species (Rhysotritia ardua, Hydrozetes lacustris, Pergalumna nervosa) were trophic generalists whereas eleven other species (e.g. Hoplophthiracarus illinoisensis, Hypochthonius rufulus) had rather narrow trophic ranges as indicated by variance in N-15 and C-13 signatures. Isotopic signatures of similar oribatid mites collected in the green and brown parts of the Sphagnum lawn were rather close together suggesting that they use the same food sources. In the Sphagnum lawn, oribatid mites low in the food web were primary decomposers such as Platynothrus peltifer and Nothrus pratensis, whereas Oppiella spp. had high delta N-15 signatures pointing to fungal feeding or predation/scavenging. Limnozetes rugosus and Hydrozetes lacustris had the highest N-15 signatures indicating that these taxa are high in the food web possibly feeding on protozoans and nematodes living in the biofilm on the stems and branches of Sphagnum sp. (C) 2016 Elsevier Ltd. All rights reserved
Top-down control of soil microarthropods - Evidence from a laboratory experiment
No full textPredator-prey interactions are of eminent importance as structuring forces for animal communities. The present study investigates if and how strongly the density of soil microarthropods is controlled by top-down forces, i.e. predation by mesostigmate mites (Mesostigmata, Acari). We set up a laboratory experiment running for ten weeks with undisturbed soil cores taken from the field using two densities of predatory mesostigmate mites: (1) ambient density (control) and (2) increased density (addition of seven Pergamasus septentrionalis and eight Lysigamasus sp. individuals). Increased predator density resulted in a decrease in the density of Oribatida, Collembola and Protura whereas the density of other taxa including Astigmata, Prostigmata and Uropodina was not significantly affected. Additionally, the species number of Oribatida was also not significantly affected. Taxa of Oribatida and Collembola were differently affected by increased predator density. Among Collembola, densities of Poduridae and Sminthuridae were reduced, whereas Entomobryidae were not affected. Among Oribatida, densities of Oppiidae and Suctobelbidae were reduced whereas Desmonomata, Poronota and Tectocepheus were not affected. Grouping of Oribatida into different size classes and into classes differing in sclerotization suggests that smaller mites (200-300 mu m) and mites with less sclerotization were more heavily affected than larger mites and mites with strong sclerotization. The results indicate that predatory mesostigmate mites have the potential to control the density of certain taxa of soil microarthropods. In particular, small and little sclerotized prey is susceptible to predator control indicating that predator defense is an important component of the life history tactics of soil microarthropods, especially of Oribatida. (c) 2008 Elsevier Ltd. All rights reserved
Opening up new niche dimensions: The stoichiometry of soil microarthropods in European beech and Norway spruce forests
No full textNiche theory fundamentally contributed to the understanding of animal diversity. However, in soil, the diversity of animals seems enigmatic since the soil is a rather homogeneous habitat, and soil animals are often generalist feeders. A new approach to understand soil animal diversity is the use of ecological stoichiometry. The elemental composition of animals may explain their occurrence, distribution, and density. This approach has been used before in soil macrofauna, but this study is the first to investigate soil mesofauna. Using inductively coupled plasma optic emission spectrometry (ICP-OES), we analyzed the concentration of a wide range of elements (Al, Ca, Cu, Fe, K, Mg, Mn, Na, P, S, Zn) in 15 soil mite taxa (Oribatida, Mesostigmata) from the litter of two different forest types (beech, spruce) in Central Europe (Germany). Additionally, the concentration of carbon and nitrogen, and their stable isotope ratios (15N/14N, 13C/12C), reflecting their trophic niche, were measured. We hypothesized that (1) stoichiometry differs between mite taxa, (2) stoichiometry of mite taxa occurring in both forest types is not different, and (3) element composition is correlated to trophic level as indicated by 15N/14N ratios. The results showed that stoichiometric niches of soil mite taxa differed considerably indicating that elemental composition is an important niche dimension of soil animal taxa. Further, stoichiometric niches of the studied taxa did not differ significantly between the two forest types. Calcium was negatively correlated with trophic level indicating that taxa incorporating calcium carbonate in their cuticle for defense occupy lower trophic positions in the food web. Furthermore, a positive correlation of phosphorus with trophic level indicated that taxa higher in the food web have higher energetic demand. Overall, the results indicate that ecological stoichiometry of soil animals is a promising tool for understanding their diversity and functioning.Deutsche Forschungsgemeinschaft http://dx.doi.org/10.13039/501100001659Open-Access-Publikationsfonds 202
Oribatid mites reveal that competition for resources and trophic structure combine to regulate the assembly of diverse soil animal communities
Full text linkThe role of niche partitioning in structuring species‐rich soil animal communities has been debated for decades and generated the “enigma of soil animal diversity.” More recently, resource‐based niche partitioning has been hypothesized to play a very limited role in the assembly of soil animal communities. To test this hypothesis, we applied a novel combination of stable isotopes and null models of species co‐occurrence to quantify the extent of resource niche partitioning on a diverse oribatid mite community sampled from mature oak woodland.We asked whether species aggregate or segregate spatially and how these patterns correlated with the abundance of estimated trophic guilds. We also estimated the effects of environmental variables on community structure.All measured environmental variables accounted for 12% of variance in community structure, including 8% of pure spatial structure unrelated to measured environmental factors and 2% of pure environmental variance unrelated to spatial variation. Co‐occurrence analysis revealed 10 pairs of species that aggregated and six pairs of species that were spatially segregated. Values of δ15N indicated that five out of the 10 pairs of aggregated species occupied the same trophic guild, while values of δ13C indicated that species in these five pairs consumed resources of different quality, supporting a significant role of resource‐based niche partitioning. Also, one of the five pairs of segregated species occupied the same trophic guild but had overlapping δ13C values suggesting that these species do not co‐occur locally and thus minimize competition for shared resources.Partitioning of resources plays an underestimated role in soil microarthropod communities and different local communities consisted of the same trophic guilds with species identity changing from place to place. The sum of resource partitioning, multi‐trophic interactions, and microscale environmental variability in the environment is a viable solution to the enigma of soil animal diversit
Trophic diversity and niche partitioning in a species rich predator guild – Natural variations in stable isotope ratios (13C/12C, 15N/14N) of mesostigmatid mites (Acari, Mesostigmata) from Central European beech forests
No full textA large number of predatory mesostigmatid mite species populate forest soils in high densities. The present study investigates the trophic structure of the Mesostigmata community of old growth beech stands in Central Germany and identifies potential prey groups using natural variations in stable isotope ratios (C-13/C-12 and N-15/N-14). Data on relative abundances and body mass were included for each of the 40 species studied to analyze functional aspects in Mesostigmata feeding ecology. The results indicate that Mesostigmata predominantly feed on secondary decomposers, whereas primary decomposer and intra-guild prey are of minor importance. Dominant species featured high delta C-13 signatures suggesting that they predominantly feed on species relying on root derived resources such as bacterial feeding nematodes. Less abundant species where characterized by lower delta C-13 values suggesting that they predominantly feed on prey relying on litter derived resources such as fungal feeding Collembola. Related taxa often had distinctively different isotope ratios suggesting that trophic niche partitioning facilitates coexistence of morphologically similar species. Unexpectedly, the trophic position of Mesostigmata species was not related to body size reflecting the varying trophic position of their main prey, nematodes and Collembola, suggesting that body size is a poor predictor of trophic position in soil food webs. (C) 2012 Elsevier Ltd. All rights reserved.German Research Foundation (DFG) [1374
The sense of a beginning : Bakhtinian dialogic criticism on 'the gospel' in Mark.
Full text linkContemporary literary approaches have caused paradigm shifts in Biblical Studies in the last two decades as it appears in a great deal of Markan studies using narrative, reader-response, deconstructive, feminist, and new historicist approaches. However, literary studies on the Gospel of Mark have not taken into account theoretical questions underlying those approaches. As a result biblical critics are driven by new trends without ever having a chance to examine the critical baggage of the approaches. Consequently, there is a gap of communication between the old and the new one. Therefore this thesis is an attempt to meet the need of enhancing the quality of critical endeavour in biblical studies. In the light of most recent competing critical theories of literature, the first contribution of this thesis is the methodological finding that Bakhtinian dialogic criticism contains the most profound philosophical and practical foundations for solving some crucial theoretical problems in contemporary literary theories. It is a critique to a Saussurian linguistic system of language which becomes the very foundation of modern and postmodern literary criticism. Bakhtinian literary theory shifts the foundation of literary criticism on linguistic signs into the creative activity of the socio-cultural production of human communication. The shift into socio-cultural reality of language communication makes the notion of 'genre' very important to unlock the problem of text and context in literary studies. Since the Gospel of Mark has fascinated most literary critics in Biblical Studies, the problem of 'genre' of this gospel is chosen as the focus of this study. Secondly, as no agreement is reached as to what 'genre' the Gospel of Mark belongs, this thesis makes its contribution to the discussion by locating the problem of 'genre' of Mark in the context of genre theories and argues that the Bakhtinian suggestion to find genre in the socio-cultural sphere by analysing artistic intercourse between narrative agents in Mark has freed the competing analysis from the unresolved problem between the kerygmatic (content oriented) approach and the analogical (form oriented) approach. To achieve finding 'genre' in the socio-cultural sphere, this thesis focuses on Bakhtinian analysis of the process of artistic intercourse between narrative agents. The narrative communicative interrelationships between narrative agents is constructed in this thesis as a 'stereophonic' Bakhtinian model of dialogic communication. This model is an original contribution of this thesis for revising the traditional two dimensional model of narrative communication. Based on this dialogical model of communication, a special role is given to the Bakhtinian 'author-creator' in the realization process of genre through the interaction of polyphonic voices. Through the interaction of voices of the author-artist and the hero we are led to discover a relatively stable type of portraying and controlling reality in Mark, known as the genre of Roman 'satire'. The closest literary affinity is Satyrica by Petronius. This narrative strategy of 'satire' in Mark has its root in the prophetic discourse of the Old Testament which is saturating the speech of the narrator, John the Immerser, the centurion, the people, and even Jesus. Finally, the whole search for Markan 'genre' culminates in the analysis of the realization of genre through the analysis of Bakhtinian chronotope. The reality of the genre of Mark is its social reality that is in its role as dpxrj/ 'beginning'. As the Gospel of Mark proclaims itself as 'a beginning', it defines its claim of socio-cultural 'authority' in early Christianity. It is this 'sense of beginning' which enables the narrating and the narrated world of Mark to interact dialogically
Trophic ecology of three marine polychaete species: Evidence from laboratory experiments using stable isotope (15N, 13C), fatty acid (NLFA) analyses, and C and N stoichiometry
No full textRegional factors rather than forest type drive the community structure of soil living oribatid mites (Acari, Oribatida)
Full text linkMost European forests are managed by humans. However, the manner and intensity of management vary. While the effect of forest management on above-ground communities has been investigated in detail, effects on the below-ground fauna remain poorly understood. Oribatid mites are abundant microarthropods in forest soil and important decomposers in terrestrial ecosystems. Here, we investigated the effect of four forest types (i.e., managed coniferous forests; 30 and 70 years old managed beech forests; natural beech forests) on the density, diversity and community structure of oribatid mites (Acari). The study was replicated at three regions in Germany: the Swabian Alb, the Hainich and the Schorfheide. To relate changes in oribatid mite community structure to environmental factors, litter mass, pH, C and N content of litter, fine roots and C content of soil were measured. Density of oribatid mites was highest in the coniferous forests and decreased in the order 30 years old, 70 years old, and natural beech forests. Mass of the litter layer and density of oribatid mites were strongly correlated indicating that the litter layer is an important factor regulating oribatid mite densities. Diversity of oribatid mites was little affected by forest type indicating that they harbor similar numbers of niches. Species composition differed between the forest types, suggesting different types of niches. The community structure of oribatid mites differed more strongly between the three regions than between the forest types indicating that regional factors are more important than effects associated with forest type.DFG [BR 2315/7-1
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