Latest finding - Plant Ecology and Phytochemistry
- Understanding the structure of plant–pollinator interaction webs
Plant–pollinator interaction webs exhibit consistent structural features such as long-tailed distributions of the degree of generalization, nestedness of interactions and asymmetric interaction dependencies. Recognition of these shared features has led to a variety of mechanistic explanations. We hypothesized that, beside size thresholds and species abundances, the frequency distributions of nectar depths and proboscis lengths play a key role in interaction patterns.
We introduced a new network parameter to test the influence of these size distributions: the degree of size matching between nectar depth and proboscis length. The observed degree of size matching in a Spanish plant–pollinator web was compared with the expected degree based on joint probability distributions, integrating size thresholds and species abundance, and taking the sampling method into account.
Nectar depths and proboscis lengths both exhibited right-skewed frequency distributions between as well as within species. The extent of size matching was similar across plant species, independent of nectar depth. However, we found significant variation among pollinator species dependent on proboscis length. The observed patterns were predicted well by a model including size distributions across species and relative species abundances, especially for flowers with openly accessible nectar and pollinators with long proboscises.
Our results suggest that size distributions are indeed important for interaction patterns in plant–pollinator webs. We now believe that our understanding will be further improved by characterizing entire communities in how nectar production of flowers and energetic requirements of pollinators covary with size.
Martina Stang, Peter Klinkhamer, Nickolas Waser, Ingo Stang and Eddy van der Meijden published their finding in June 2009 in a Special Issue of Annals of Botany about Plant - Pollinator Interactions.
LINK TO: http://aob.oxfordjournals.org/cgi/content/abstract/103/9/1459
