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Food Choice of Antarctic Soil Arthropods Clarified by Stable Isotope Signatures

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Food Choice of Antarctic Soil Arthropods Clarified by Stable Isotope Signatures VU Research Portal Free energies of binding of R- and S-propranolol to wild-type and F483A mutant cytochrome P450 2D6 from molecular dynamics simulations de Graaf, C.; Oostenbrink, C.; Keizers, P.H.J.; van Vugt-Lussenburg, B.M.A.; Commandeur, J.N.M.; Vermeulen, N.P.E. published in European Biophysics Journal 2007 DOI (link to publisher) 10.1007/s00249-006-0126-y 10.1007/s00249-006-0126-y document version Publisher's PDF, also known as Version of record Link to publication in VU Research Portal citation for published version (APA) de Graaf, C., Oostenbrink, C., Keizers, P. H. J., van Vugt-Lussenburg, B. M. A., Commandeur, J. N. M., & Vermeulen, N. P. E. (2007). Free energies of binding of R- and S-propranolol to wild-type and F483A mutant cytochrome P450 2D6 from molecular dynamics simulations. European Biophysics Journal, 36(6), 589-599. https://doi.org/10.1007/s00249-006-0126-y, https://doi.org/10.1007/s00249-006-0126-y General rights Copyright and moral rights for the publications made accessible in the public portal are retained by the authors and/or other copyright owners and it is a condition of accessing publications that users recognise and abide by the legal requirements associated with these rights. • Users may download and print one copy of any publication from the public portal for the purpose of private study or research. • You may not further distribute the material or use it for any profit-making activity or commercial gain • You may freely distribute the URL identifying the publication in the public portal ? Take down policy If you believe that this document breaches copyright please contact us providing details, and we will remove access to the work immediately and investigate your claim. E-mail address: [email protected] Download date: 29. Sep. 2021 Polar Biol (2007) 30:983–990 DOI 10.1007/s00300-007-0256-4 ORIGINAL PAPER Food choice of Antarctic soil arthropods clarified by stable isotope signatures S. Bokhorst Æ C. Ronfort Æ A. Huiskes Æ P. Convey Æ R. Aerts Received: 14 November 2006 / Revised: 10 January 2007 / Accepted: 13 January 2007 / Published online: 22 February 2007 Ó Springer-Verlag 2007 Abstract Antarctic soil ecosystems are amongst the Keywords Alaskozetes antarcticus Á Antarctic Á most simplified on Earth and include only few soil Collembola Á Cryptopygus antarcticus Á Food choice arthropod species, generally believed to be opportu- nistic omnivorous feeders. Using stable isotopic anal- yses, we investigated the food choice of two common Introduction and widely distributed Antarctic soil arthropod species using natural abundances of 13Cand15N and an iso- Soil arthropods are known to play an important role in tope labelling study. In the laboratory we fed the iso- decomposition processes and nutrient flows through tomid springtail Cryptopygus antarcticus six potential the soil ecosystem (Brussaard 1998; Filser 2002). food sources (one algal species, two lichens and three However, detailed knowledge of the specific role of mosses). Our results showed a clear preference for al- individual species in the soil ecosystem is necessary to gae and lichens rather than mosses. These results were better understand ecosystem processes (Faber 1991). corroborated by field data comparing stable isotope Food availability is likely to be an important determi- signatures from the most dominant cryptogams and soil nant of the functional composition of the soil arthro- arthropods (C. antarcticus and the oribatid mite Alas- pod fauna (Hodkinson and Wookey 1999), while their kozetes antarcticus). Thus, for the first time in an specific role in any soil ecosystem can only be under- Antarctic study, we present clear evidence that these stood in relation to their diet. The functional role of soil arthropods show selectivity in their choice of food soil arthropods is generally very difficult to investigate, and have a preference for algae and lichens above due to the complexity of most soil food webs. How- mosses. ever, in the typically species-poor Antarctic terrestrial ecosystems the soil food web is relatively simple (Convey 2001), which makes them very suitable for S. Bokhorst (&) Á C. Ronfort Á A. Huiskes addressing this type of question. However, to date very Centre for Estuarine and Marine Ecology, few studies have addressed this subject in Antarctic soil Netherlands Institute of Ecology, Korringaweg 7, ecosystems, see review by Hogg et al. (2006). 4401 NT Yerseke, The Netherlands e-mail: [email protected] Within Antarctic soils and vegetated ecosystems there are only a small number of arthropod species P. Convey (Davis 1981; Usher and Booth 1986; Convey et al. Natural Environmental Research Council, 1996, 1997; Convey 2001; Sinclair 2001). However, the British Antarctic Survey, High Cross, Madingley Road, Cambridge CB3 0ET, UK abundance of some of these arthropods (e.g. the iso- tomid springtail Cryptopygus antarcticus) can be very R. Aerts high, up to 106 individuals m–2 (Convey and Smith Institute of Ecological Science, 1997), while communities are often dominated by only Department of Systems Ecology, Vrije Universiteit, De Boelelaan 1085, one or two species (Goddard 1979; Block 1982; Rich- 1081 HV Amsterdam, The Netherlands ard et al. 1994). These large numbers suggest that there 123 984 Polar Biol (2007) 30:983–990 must be ample food available, and there is a generally Material and methods accepted, but generally untested, assumption that food resources are not limiting for these arthropods (Con- Sampling site vey 1996). Maritime Antarctic vegetation is primarily com- Cryptogam and soil arthropod specimens were collected posed of cryptogams (Longton 1967; Convey 2001) from Anchorage Island (maritime Antarctic). Anchor- with mosses as the group that sequesters most of the age Island is one of the Le´onie Islands and lies in Mar- carbon. As there are no large herbivores, almost all this guerite Bay south of the Rothera Research Station of carbon is transferred to the soil (Davis 1981). It has the British Antarctic Survey (67°61¢S68°22¢W). The previously been suggested that most of the carbon and island is 2.5 km long and 500 m wide and is partly cov- nutrients will flow directly into the decomposition ered by semi-permanent snow and ice fields. The island pathway without passing through a consumer level includes several rocky ridges with a maximum height of (Block 1985). However, the contribution of the domi- 57 m a.s.l. On the slopes of these ridges, there are some nant groups of soil arthropods, springtails and mites, patches of the moss Sanionia uncinata (Hedw.) Loeske, within these nutrient flows is not well understood. and the grass Deschampsia antarctica Desv. However, Most existing data on feeding preferences of Ant- the vegetation consists mainly of lichens, with Usnea arctic soil arthropods is based on analysis of the gut antarctica being most prominent. content (Broady 1979; Burn 1981, 1984; Davidson and Broady 1996). This approach, while widely used, has Feeding experiments with the springtail the drawback that only the material that passes Cryptopygus antarcticus through the gut of an organism undamaged can be determined (Chamberlain et al. 2006a, b), while there Cryptopygus antarcticus is by far the most abundant is usually a large component of unidentifiable material springtail in vegetated habitats of Anchorage Island remaining (Davis 1981). The use of stable isotopic (Convey and Smith 1997). Recent molecular phyloge- analyses in soil food web studies has made it easier for netic research indicates that material currently referred ecologists to assess the role of soil organisms (Neilson to this species across its wide maritime and sub-Ant- et al. 1998; Briones et al. 1999; Scheu and Falca 2000; arctic distribution is likely to represent several distinct Schmidt et al. 2004; Staddon 2004). More importantly, lineages, with that from the Antarctic Peninsula assumptions about feeding preferences of species have referable to the subspecies C. antartcticus antarcticus been changed as a result of the use of this technique (Stevens et al. 2006). Live specimens of Cryptopygus (Chamberlain et al. 2006a). Applying this technique on (henceforth referred to by generic name only) were the components of Antarctic soil ecosystems will en- transported to The Netherlands in plastic boxes with able increased understanding of the feeding strategies algae and mosses at 4°C. Two feeding experiments of Antarctic soil arthropods, and of the specific roles were performed. In the first experiment 20 individuals these soil arthropods play in nutrient cycling in these of Cryptopygus were placed in each of 30 polystyrene ecosystems. Various studies have shown that the stable pots with a base of plaster of Paris. In all pots one of isotope signatures (d13C and d15N) of cryptogams differ the following six food sources was placed: Prasiola considerably between species (Galimov 2000; Huiskes crispa (alga), Umbilicaria decussata (lichen), U. ant- et al. 2006). These stable isotope differences in the arctica (lichen), S. uncinata (moss), Pohlia nutans producers should therefore lead to differences in con- (moss) or Brachythecium austrosalebrosum (moss), sumer isotope ratios and assist in the determination of each replicated five times. All these species occur feeding preferences. naturally within local maritime Antarctic ecosystems. The aim of this study was to assess the food choice The pots were maintained in a climate chamber at 2°C of the most dominant soil arthropods in maritime for 6 weeks, the temperature being selected as it is the Antarctic soil ecosystems. We used two complemen- mean summer soil temperature at this location in the tary approaches: (1) laboratory feeding-experiments maritime Antarctic (S. Bokhorst et al. submitted). with labelled and non-labelled food using C. antarcticus After this period, Cryptopygus and cryptogam samples in order to determine which food sources are preferred were freeze-dried and analysed for their 13C and 15N by this species: and (2) a field survey on Anchorage content.
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