Macroecology of pollination networks

Aim Interacting communities of species are organized into complex networks, and network analysis is reckoned to be a strong tool for describing their architecture. Many species assemblies show strong macroecological patterns, e.g. increasing species richness with decreasing latitude, but whether this latitudinal diversity gradient scales up to entities as complex as networks is unknown. We investigated this using a dataset of 54 community-wide pollination networks and hypothesized that pollination networks would display a latitudinal and altitudinal species richness gradient, increasing specialization towards the tropics, and that network topology would be affected by current climate. Location Global. Methods Each network was organized as a presence/absence matrix, consisting of P plant species, A pollinator species and their links. From these matrices, network parameters were estimated. Additionally, data about geography (latitude, elevation), climate at the network site (temperature, precipitation) and sampling effort (observation days) and extent (study-plot size) were gathered. Analyses were done using simultaneous autoregressive modelling (SAR). Results Species richness did not vary strongly with either latitude or elevation. However, network modularity decreased significantly with latitude whereas mean number of links per plant species (L p) and A/P ratio peaked at mid-latitude. Above 500 m a.s.l., A/P ratio decreased and mean number of links per pollinator species (L a) increased with elevation. L p displayed mid-ambient peaks with temperature and nestedness and modularity displayed linear relationships with precipitation. Main conclusion Pollination networks showed macroecological patterns. No strong latitudinal or altitudinal gradient in species richness was observed. L p and the A/P ratio peaked at mid-latitude whereas modularity decreased linearly. Both patterns are suggestive of a more specialized interaction structure towards the tropics. In particular, mean annual precipitation appeared influential on network topology as both nestedness and modularity varied significantly. Importantly, corrected regressions suggest that neither sampling effort nor extent affected the observed patterns.

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

[2]  Richard Field,et al.  Coefficient shifts in geographical ecology: an empirical evaluation of spatial and non-spatial regression , 2009 .

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

[4]  Theodora Petanidou,et al.  Spatio‐temporal variation in the structure of pollination networks , 2009 .

[5]  H. Campbell,et al.  Hello New Zealand , 2006 .

[6]  Makoto Kato,et al.  Insect-flower Relationship in the Temperate Deciduous Forest of Kibune, Kyoto : An Overview of the Flowering Phenology and the Seasonal Pattern of Insect Visits , 1990 .

[7]  Dawn M. Kaufman,et al.  LATITUDINAL GRADIENTS OF BIODIVERSITY:Pattern,Process,Scale,and Synthesis , 2003 .

[8]  Anders Nielsen,et al.  Conservation of species interaction networks , 2010 .

[9]  Joseph Tzanopoulos,et al.  Long-term observation of a pollination network: fluctuation in species and interactions, relative invariance of network structure and implications for estimates of specialization. , 2008, Ecology letters.

[10]  Ana M. Martín González,et al.  Specialization in Plant-Hummingbird Networks Is Associated with Species Richness, Contemporary Precipitation and Quaternary Climate-Change Velocity , 2011, PloS one.

[11]  A. Timmermann,et al.  Effects of climate on pollination networks in the West Indies , 2009, Journal of Tropical Ecology.

[12]  J. Bascompte,et al.  Ecological networks : beyond food webs Ecological networks – beyond food webs , 2008 .

[13]  N. Ramírez,et al.  Pollination biology in a palm swamp community in the Venezuelan Central Plains , 1992 .

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

[15]  Werner Ulrich,et al.  A consistent metric for nestedness analysis in ecological systems: reconciling concept and measurement , 2008 .

[16]  J. Bosch,et al.  Plant-pollinator networks: adding the pollinator's perspective. , 2009, Ecology letters.

[17]  D. Schemske,et al.  Flowering Ecology of Some Spring Woodland Herbs , 1978 .

[18]  G. Wallis,et al.  New Zealand phylogeography: evolution on a small continent , 2009, Molecular ecology.

[19]  Jordi Bascompte,et al.  Non-random coextinctions in phylogenetically structured mutualistic networks , 2007, Nature.

[20]  B. Hocking,et al.  Insect-flower associations in the high Arctic with special reference to nectar' , 1968 .

[21]  Carsten F. Dormann,et al.  Ecological networks - foodwebs and beyond , 2009 .

[22]  R. G. Davies,et al.  Methods to account for spatial autocorrelation in the analysis of species distributional data : a review , 2007 .

[23]  S. Barrett,et al.  The reproductive biology of boreal forest herbs. I. Breeding systems and pollination , 1987 .

[24]  Roger Guimerà,et al.  Cartography of complex networks: modules and universal roles , 2005, Journal of statistical mechanics.

[25]  M. Devoto,et al.  Patterns of interaction between plants and pollinators along an environmental gradient , 2005 .

[26]  J. Bascompte,et al.  The modularity of pollination networks , 2007, Proceedings of the National Academy of Sciences.

[27]  L. Freitas,et al.  POLLINATION BIOLOGY IN A TROPICAL HIGH-ALTITUDE GRASSLAND IN BRAZIL: INTERACTIONS AT THE COMMUNITY LEVEL1, 2 , 2006 .

[28]  Jens M. Olesen,et al.  The Dense and Highly Connected World of Greenland's Plants and Their Pollinators , 2005 .

[29]  K. Gaston,et al.  Spatial patterns in the geographic range sizes of bird species in the New World , 1996 .

[30]  K. Gaston.  Global patterns in biodiversity , 2000, Nature.

[31]  Neo D. Martinez,et al.  Food-web structure and network theory: The role of connectance and size , 2002, Proceedings of the National Academy of Sciences of the United States of America.

[32]  José Alexandre Felizola Diniz-Filho,et al.  Modelling geographical patterns in species richness using eigenvector-based spatial filters , 2005 .

[33]  Jennifer A. Dunne,et al.  How to monitor ecological communities cost-efficiently: The example of plant–pollinator networks , 2010 .

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

[35]  D. Schemske,et al.  Geographic patterns in plant-pollinator mutualistic networks: Comment , 2004 .

[36]  T. D. Mitchell,et al.  An improved method of constructing a database of monthly climate observations and associated high‐resolution grids , 2005 .

[37]  W. D. Kissling,et al.  Spatial autocorrelation and the selection of simultaneous autoregressive models , 2007 .

[38]  T. Rangel,et al.  SAM: a comprehensive application for Spatial Analysis in Macroecology , 2010 .

[39]  Pedro Jordano,et al.  Patterns of Mutualistic Interactions in Pollination and Seed Dispersal: Connectance, Dependence Asymmetries, and Coevolution , 1987, The American Naturalist.

[40]  H. Campbell,et al.  GUEST EDITORIAL: Hello New Zealand , 2006 .

[41]  J. Diniz‐Filho,et al.  ‘Latitude’ and geographic patterns in species richness , 2004 .

[42]  D. Vázquez,et al.  The Latitudinal Gradient in Niche Breadth: Concepts and Evidence , 2004, The American Naturalist.

[43]  Javier Herrera,et al.  Pollination relationships in southern Spanisch Mediterranean shrublands , 1988 .

[44]  Jordi Bascompte,et al.  The smallest of all worlds: pollination networks. , 2006, Journal of theoretical biology.

[45]  Toke T. Høye,et al.  Rapid advancement of spring in the High Arctic , 2007, Current Biology.

[46]  Jeff Ollerton,et al.  Year‐to‐year variation in the topology of a plant–pollinator interaction network , 2008 .

[47]  Colin M Beale,et al.  Regression analysis of spatial data. , 2010, Ecology letters.

[48]  Guy Woodward,et al.  Body size in ecological networks. , 2005, Trends in ecology & evolution.

[49]  F. Chapin,et al.  EFFECTS OF BIODIVERSITY ON ECOSYSTEM FUNCTIONING: A CONSENSUS OF CURRENT KNOWLEDGE , 2005 .

[50]  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.

[51]  J Memmott,et al.  The structure of a plant-pollinator food web. , 1999, Ecology letters.

[52]  C. Michener.  Biogeography of the Bees , 1979 .

[53]  Helmut Hillebrand,et al.  On the Generality of the Latitudinal Diversity Gradient , 2004, The American Naturalist.

[54]  Daniel B. Stouffer,et al.  Nestedness versus modularity in ecological networks: two sides of the same coin? , 2010, The Journal of animal ecology.

[55]  Pedro Jordano,et al.  GEOGRAPHIC PATTERNS IN PLANT–POLLINATOR MUTUALISTIC NETWORKS , 2002 .

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

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

[58]  Jordi Bascompte,et al.  Ecological networks, nestedness and sampling effort , 2007 .

[59]  Juan J. Armesto,et al.  COMMUNITY STUDIES IN POLLINATION ECOLOGY IN THE HIGH TEMPERATE ANDES OF CENTRAL CHILE. I. POLLINATION MECHANISMS AND ALTITUDINAL VARIATION , 1982 .

[60]  Makoto Kato.  Anthophilous insect community and plant-pollinator interactions on Amami Islands in the Ryukyu Archipelago, Japan (Original paper) , 2000 .

[61]  Ø. Totland,et al.  Factors related to the inter-annual variation in plants' pollination generalization levels within a community , 2010 .

[62]  M. Aizen,et al.  Direct effects of habitat area on interaction diversity in pollination webs. , 2010, Ecological applications : a publication of the Ecological Society of America.

[63]  Richard B. Primack,et al.  Insect pollination in the New Zealand mountain flora , 1983 .

[64]  Mary Percival,et al.  Floral Ecology of Coastal Scrub in Southeast Jamaica , 1974 .

[65]  Shinji Sugiura.  Species interactions–area relationships: biological invasions and network structure in relation to island area , 2010, Proceedings of the Royal Society B: Biological Sciences.

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

[67]  Jordi Bascompte,et al.  Temporal dynamics in a pollination network. , 2008, Ecology.

[68]  Sd Johnson,et al.  Geographical Variation in Diversity and Specificity of Pollination Systems , 2006 .

[69]  D. Currie.  Energy and Large-Scale Patterns of Animal- and Plant-Species Richness , 1991, The American Naturalist.

[70]  G. Mittelbach,et al.  Is There a Latitudinal Gradient in the Importance of Biotic Interactions , 2009 .

[71]  H. Siegismund,et al.  Structure of a plant-pollinator network on a pahoehoe lava desert of the Galapagos Islands , 2006 .

[72]  Diego P. Vázquez,et al.  Changes in interaction biodiversity induced by an introduced ungulate , 2003 .

[73]  N. Bartoloni,et al.  Plant-pollinator Relationships at Two Altitudes in the Andes of Mendoza, Argentina , 2002 .

[74]  J. Olesen,et al.  Ecological modules and roles of species in heathland plant-insect flower visitor networks. , 2009, The Journal of animal ecology.

[75]  J. Olesen,et al.  Invasion of pollination networks on oceanic islands: importance of invader complexes and endemic super generalists , 2002 .

[76]  Jordi Bascompte,et al.  Missing and forbidden links in mutualistic networks , 2011, Proceedings of the Royal Society B: Biological Sciences.

[77]  Jeremy T. Kerr,et al.  Habitat heterogeneity as a determinant of mammal species richness in high-energy regions , 1997, Nature.

[78]  W. Jetz,et al.  Global patterns and determinants of vascular plant diversity , 2007, Proceedings of the National Academy of Sciences.

[79]  R. Guimerà,et al.  Functional cartography of complex metabolic networks , 2005, Nature.