title: Food-web structure in relation to environmental gradients and predator-prey ratios in tank-bromeliad ecosystems.
abstract: Little is known of how linkage patterns between species change along environmental gradients. The small, spatially discrete food webs inhabiting tank-bromeliads provide an excellent opportunity to analyse patterns of community diversity and food-web topology (connectance, linkage density, nestedness) in relation to key environmental variables (habitat size, detrital resource, incident radiation) and predators:prey ratios. We sampled 365 bromeliads in a wide range of understorey environments in French Guiana and used gut contents of invertebrates to draw the corresponding 365 connectance webs. At the bromeliad scale, habitat size (water volume) determined the number of species that constitute food-web nodes, the proportion of predators, and food-web topology. The number of species as well as the proportion of predators within bromeliads declined from open to forested habitats, where the volume of water collected by bromeliads was generally lower because of rainfall interception by the canopy. A core group of microorganisms and generalist detritivores remained relatively constant across environments. This suggests that (i) a highly-connected core ensures food-web stability and key ecosystem functions across environments, and (ii) larger deviations in food-web structures can be expected following disturbance if detritivores share traits that determine responses to environmental changes. While linkage density and nestedness were lower in bromeliads in the forest than in open areas, experiments are needed to confirm a trend for lower food-web stability in the understorey of primary forests.
authors: EcoFoG, Ecologie des Forêts de Guyane, CNRS UMR 8172, Kourou, France.
authors: Olivier
authors: O
authors: Dézerald
authors: Céline
authors: C
authors: Leroy
authors: Bruno
authors: B
authors: Corbara
authors: Jean-François
authors: JF
authors: Carrias
authors: Laurent
authors: L
authors: Pélozuelo
authors: Alain
authors: A
authors: Dejean
authors: Régis
authors: R
authors: Céréghino
mesh_terms: D000818:Animals; D001499:Bayes Theorem; D044822:Biodiversity; D031231:Bromelia / Q000502:physiology*; D020387:Food Chain; D005616:French Guiana; D005843:Geography; D008954:Models, Biological; D011235:Predatory Behavior / Q000502:physiology*
references: Ecol Lett. 2009 Oct;12(10):1016-28
references: 19702635
references: Am J Bot. 2011 May;98(5):872-95
references: 21613186
references: Proc Biol Sci. 2009 Aug 22;276(1669):3027-33
references: 19515662
references: Ecol Lett. 2009 Nov;12(11):1210-8
references: 19723282
references: Science. 2009 Jul 24;325(5939):416-9
references: 19628856
references: New Phytol. 2009;183(4):1124-1133
references: 19500265
references: J Anim Ecol. 2010 Sep;79(5):1122-31
references: 20584097
references: PLoS One. 2011;6(5):e20129
references: 21625603
references: Ecology. 2010 May;91(5):1549-56
references: 20503886
references: Proc Natl Acad Sci U S A. 2003 Aug 5;100(16):9383-7
references: 12881488
references: Ecol Lett. 2011 Nov;14(11):1170-81
references: 21951949
references: Science. 2003 Feb 28;299(5611):1388-91
references: 12610303
references: Environ Manage. 2005 Dec;36(6):775-91
references: 16206018
references: Ecol Lett. 2006 Feb;9(2):215-27
references: 16958886
references: Proc Natl Acad Sci U S A. 2002 Oct 1;99(20):12917-22
references: 12235364