title: Quantity and quality components of effectiveness in insular pollinator assemblages.
abstract: Ecologically isolated habitats (e.g., oceanic islands) favor the appearance of small assemblages of pollinators, generally characterized by highly contrasted life modes (e.g., birds, lizards), and opportunistic nectar-feeding behavior. Different life modes should promote a low functional equivalence among pollinators, while opportunistic nectar feeding would lead to reduced and unpredictable pollination effectiveness (PE) compared to more specialized nectarivores. Dissecting the quantity (QNC) and quality (QLC) components of PE, we studied the opportunistic bird-lizard pollinator assemblage of Isoplexis canariensis from the Canary Islands to experimentally evaluate these potential characteristics. Birds and lizards showed different positions in the PE landscape, highlighting their low functional equivalence. Birds were more efficient than lizards due to higher visitation frequency (QNC). Adult lizards differed from juveniles in effecting a higher production of viable seeds (QLC). The disparate life modes of birds and lizards resulted in ample intra- and inter-specific PE variance. The main sources of PE variance were visitation frequency (both lizards and birds), number of flowers probed (lizards) and proportion of viable seeds resulting from a single visit (birds). The non-coincident locations of birds and lizards on the PE landscape indicate potential constraints for effectiveness. Variations in pollinator abundance can result in major effectiveness shifts only if QLC is relatively high, while changes in QLC would increase PE substantially only at high QNC. The low functional equivalence of impoverished, highly contrasted pollinator assemblages may be an early diagnostic signal for pollinator extinction potentially driving the collapse of mutualistic services.
authors: Integrative Ecology Group, Estación Biológica de Doñana, Isla de la Cartuja, Sevilla, Spain. canderguez@ebd.csic.es
authors: María C
authors: MC
authors: Rodríguez-Rodríguez
authors: Pedro
authors: P
authors: Jordano
authors: Alfredo
authors: A
authors: Valido
mesh_terms: D000818:Animals; D001717:Birds / Q000502:physiology*; D005247:Feeding Behavior; D008116:Lizards / Q000502:physiology*; D010943:Plantago / Q000502:physiology*; D054817:Pollination; D013030:Spain
references: Science. 1984 Aug 3;225(4661):519-21
references: 17750855
references: Oecologia. 2008 May;156(2):325-32
references: 18283498
references: Oecologia. 2007 Sep;153(3):597-605
references: 17576602
references: Biol Rev Camb Philos Soc. 2010 Aug;85(3):435-51
references: 20015317
references: Evolution. 2003 Dec;57(12):2742-52
references: 14761053
references: Oecologia. 1989 Aug;80(2):241-248
references: 28313114
references: Am J Bot. 2003 Feb;90(2):214-25
references: 21659111
references: New Phytol. 2010 Oct;188(2):333-53
references: 20673283
references: Bull Entomol Res. 2011 Oct;101(5):557-64
references: 21457587
references: Oecologia. 2005 Dec;146(3):394-403
references: 16133196
references: Am Nat. 2003 Oct;162(4 Suppl):S24-39
references: 14583855
references: Proc Natl Acad Sci U S A. 2009 Jun 9;106(23):9322-7
references: 19470638
references: Proc Natl Acad Sci U S A. 2007 Dec 11;104(50):19891-6
references: 18056808
references: Am J Bot. 2004 May;91(5):672-81
references: 21653422
references: Mol Phylogenet Evol. 2006 Feb;38(2):381-97
references: 16054402
references: Science. 1972 Jun 30;176(4042):1439-40
references: 17834653
references: Ecology. 2007 Feb;88(2):271-81
references: 17479745
references: Naturwissenschaften. 2009 Feb;96(2):221-32
references: 18931830
references: Am J Bot. 2008 Nov;95(11):1408-15
references: 21628148
references: Am J Bot. 2007 Mar;94(3):419-24
references: 21636411
references: Am J Bot. 2012 Jun;99(6):1104-11
references: 22688428
references: Ecology. 2006 Apr;87(4):912-21
references: 16676535
references: Science. 2011 Feb 25;331(6020):1068-71
references: 21292938