Evolutionary Ecology

, Volume 29, Issue 3, pp 419–435

Long corollas as nectar barriers in Lonicera implexa: interactions between corolla tube length and nectar volume

Original Paper

Abstract

Long corollas are a classical example of nectar barriers, because they prevent undesired visitors from consuming the reward intended for more effective pollinators. As the investment in nectar barriers increases, flower attractiveness and nectar rewards may also increase to maintain loyal visitation of most effective pollinators; and flowers may become more prone to nectar robbing. We evaluated the effect of nectar barriers (corolla tube length), two related traits (nectar volume and upper lip size) and the associated risk of nectar robbing, on the fecundity of Lonicera implexa plants from three populations differing in the abundance of its most efficient pollinator, the hummingbird hawkmoth Macroglossum stellatarum. Corolla tube length varied most among individuals within populations (45–46 % of total variance) and inflorescences within individuals (23–32 %), and showed little variation among populations (0.2–11 %). Longer corolla tubes were always associated with larger nectar volumes and larger upper lips, although the strength of the relationships varied across populations and years. Robbing frequency increased with corolla tube length, decreased with nectar volume and upper lip size, and its weak effects on fecundity were predominantly positive. Plant fecundity peaked at two different optima: long corollas with little nectar and short corollas with abundant nectar. However, the exact shape of the interaction between corolla length and nectar volume, as well as the combination of traits showing the highest fecundity, differed between populations and years. This variation could be explained by among-population differences in pollinator assemblages, and inter-annual changes in resources dedicated to reproduction. Our study shows that large nectar volumes can modulate the effect of corolla length as a nectar barrier, and that the combination of these two traits that maximises fecundity may be related to the identity of pollinators within each population.

Keywords

Corolla tube length Fecundity Floral display Nectar robbing Nectar volume Non-additive effects Selective pressures 

Supplementary material

10682_2014_9736_MOESM1_ESM.doc (36 kb)
Supplementary material 1 (DOC 35 kb)
10682_2014_9736_MOESM2_ESM.doc (215 kb)
Supplementary material 2 (DOC 208 kb)

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Copyright information

© Springer International Publishing Switzerland 2014

Authors and Affiliations

  • Amparo Lázaro
    • 1
  • Clara Vignolo
    • 1
  • Luis Santamaría
    • 2
  1. 1.Mediterranean Institute for Advanced Studies (IMEDEA)UIB-CSICEsporlesSpain
  2. 2.Doñana Biological StationSevilleSpain

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