Ecological networks, nestedness and sampling effort

Summary 1 Ecological networks have been shown to display a nested structure. To be nested, a network must consist of a core group of generalists all interacting with each other, and with extreme specialists interacting only with generalist species. 2 Studies on ecological networks are especially prone to sampling effects, as they involve entire species assemblages. However, we know of no study addressing to what extent nestedness depends on sampling effort, despite the numerous studies discussing the ecological and evolutionary implications of nested networks. 3 Here we manipulate sampling effort in time and space and show that nestedness is less sensitive to sampling effort than number of species and links within the network. 4 That a structural property of an ecological network appears less prone to sampling bias is encouraging for other studies of ecological networks. This is because it indicates that the sensitivity of ecological networks properties to effects of sampling effort might be smaller than previously expected.

[1]  Jens M. Olesen,et al.  Structure of a plant–flower‐visitor network in the high‐altitude sub‐alpine desert of Tenerife, Canary Islands , 2003 .

[2]  C. Herrera,et al.  Plant generalization on pollinators: species property or local phenomenon? , 2005, American journal of botany.

[3]  Jeff Ollerton,et al.  The pollination ecology of an assemblage of grassland asclepiads in South Africa. , 2003, Annals of botany.

[4]  J. Olesen,et al.  Bird-made fruit orchards in Northern Europe: Nestedness and network properties , 2005 .

[5]  Robert K. Colwell,et al.  Estimating terrestrial biodiversity through extrapolation. , 1994, Philosophical transactions of the Royal Society of London. Series B, Biological sciences.

[6]  Jeff Ollerton,et al.  Latitudinal trends in plant‐pollinator interactions: are tropical plants more specialised? , 2002 .

[7]  Louis-Félix Bersier,et al.  QUANTITATIVE DESCRIPTORS OF FOOD-WEB MATRICES , 2002 .

[8]  J. Bascompte,et al.  Structure in plant–animal interaction assemblages , 2006 .

[9]  Wirt Atmar,et al.  The measure of order and disorder in the distribution of species in fragmented habitat , 1993, Oecologia.

[10]  J. Thompson.  The Geographic Mosaic of Coevolution , 2005 .

[11]  Robert K. Colwell,et al.  ESTIMATION OF SPECIES RICHNESS: MIXTURE MODELS, THE ROLE OF RARE SPECIES, AND INFERENTIAL CHALLENGES , 2005 .

[12]  Bradford A. Hawkins,et al.  EFFECTS OF SAMPLING EFFORT ON CHARACTERIZATION OF FOOD-WEB STRUCTURE , 1999 .

[13]  Jeff Ollerton,et al.  Finding NEMO: nestedness engendered by mutualistic organization in anemonefish and their hosts , 2007, Proceedings of the Royal Society B: Biological Sciences.

[14]  L. Vitt,et al.  Food Web Laws or Niche Theory? Six Independent Empirical Tests , 2001, The American Naturalist.

[15]  James F. Quinn,et al.  An evaluation of randomization models for nested species subsets analysis , 1998, Oecologia.

[16]  R. Paine.  Road Maps of Interactions or Grist for Theoretical Development , 1988 .

[17]  Jordi Bascompte,et al.  The ecological consequences of complex topology and nested structure in pollination webs. , 2006 .

[18]  P. Klinkhamer,et al.  Asymmetric specialization and extinction risk in plant–flower visitor webs: a matter of morphology or abundance? , 2007, Oecologia.

[19]  Jordi Bascompte,et al.  Habitat loss and the structure of plant-animal mutualistic networks. , 2006, Ecology letters.

[20]  David B. Lindenmayer,et al.  Treating the nestedness temperature calculator as a “black box” can lead to false conclusions , 2002 .

[21]  Paulo R Guimarães,et al.  Asymmetries in specialization in ant–plant mutualistic networks , 2006, Proceedings of the Royal Society B: Biological Sciences.

[22]  Michel Loreau,et al.  Functional Diversity of Plant–Pollinator Interaction Webs Enhances the Persistence of Plant Communities , 2005, PLoS biology.

[23]  Miguel A. Rodríguez-Gironés,et al.  A new algorithm to calculate the nestedness temperature of presence–absence matrices , 2006 .

[24]  R. Lokesha,et al.  Plant-pollinator interactions , 1993 .

[25]  Luis Santamaría,et al.  Linkage Rules for Plant–Pollinator Networks: Trait Complementarity or Exploitation Barriers? , 2007, PLoS biology.

[26]  B. Krasnov,et al.  Species abundance and the distribution of specialization in host–parasite interaction networks , 2005 .

[27]  Ø. Totland,et al.  The effect of forest management operations on population performance of Vaccinium myrtillus on a landscape-scale , 2007 .

[28]  Miguel A. Fortuna,et al.  The nested structure of a scavenger community , 2007, Proceedings of the Royal Society B: Biological Sciences.

[29]  Louis-Félix Bersier,et al.  Sampling effects and the robustness of quantitative and qualitative food-web descriptors. , 2004, Journal of theoretical biology.

[30]  Jordi Bascompte,et al.  Asymmetric Coevolutionary Networks Facilitate Biodiversity Maintenance , 2006, Science.

[31]  Diego P. Vázquez,et al.  Degree distribution in plant–animal mutualistic networks: forbidden links or random interactions? , 2005 .

[32]  Paulo Guimarães,et al.  Improving the analyses of nestedness for large sets of matrices , 2006, Environ. Model. Softw..

[33]  Jane Memmott,et al.  Tolerance of pollination networks to species extinctions , 2004, Proceedings of the Royal Society of London. Series B: Biological Sciences.

[34]  Neo D. Martinez,et al.  Improving Food Webs , 1993 .

[35]  J. Bascompte,et al.  Invariant properties in coevolutionary networks of plant-animal interactions , 2002 .

[36]  Lloyd Goldwasser,et al.  SAMPLING EFFECTS AND THE ESTIMATION OF FOOD‐WEB PROPERTIES , 1997 .

[37]  Carlos J. Melián,et al.  The nested assembly of plant–animal mutualistic networks , 2003, Proceedings of the National Academy of Sciences of the United States of America.