Stefan Vogel's analysis of floral syndromes in the South African flora: An appraisal based on 60 years of pollination studies

Abstract

The concept of floral syndromes has been controversial since it was first proposed by Delpino in the nineteenth century. Some have derided the concept for being typological and inconsistent with the generalized nature of many pollination systems. However, others have lauded it for providing a testable framework for the study of convergent evolution in plants showing specialization to particular functional groups of pollinators. During the 1950s, Stefan Vogel assigned floral syndromes to 810 plant species in South Africa. Now, 60 years later, data on the pollination systems of 272 of these species allow us to test whether the floral syndromes Vogel assigned to them are consistent with their actual pollinators. The overwhelming majority (99.6%) of species in Vogel’s sample that have been investigated in the field appear to be ecologically specialized for pollination by a particular functional pollinator group. We found that Vogel’s syndrome classification accurately predicted pollinators for almost 82% of species. The highest accuracy (93%) was for the prediction of bird pollinators from the floral syndrome of “ornithophily”, while the lowest accuracy (68%) was for the prediction of hawkmoth pollination from the floral syndrome of “sphingophily”. The degree of accuracy of pollinator predictions based on floral syndromes did not vary significantly among plant families, despite differences in floral construction and levels of ecological specialization among these lineages. This study provides support for the concept of floral pollination syndromes by demonstrating the existence of strong associations between floral phenotypes and pollinators in a region of high biodiversity.