Using geometric morphometrics to determine the “fittest” floral shape: A case study in large-flowered, buzz-pollinated Meriania hernandoi

Agnes S. Dellinger, Daniela Hanusch, Mario Oswald, Diana Fernández-Fernández, Jürg Schönenberger

Abstract Premise Floral shape (relative arrangement and position of floral organs) is critical in mediating fit with pollinators and maximizing conspecific pollen transfer particularly in functionally specialized systems. To date, however, few studies have attempted to quantify flowers as the inherently three-dimensional (3D) structures they are and determine the effect of intraspecific shape variation on pollen transfer. We here addressed this research gap using a functionally specialized system, buzz pollination, in which bees extract pollen through vibrations, as a model. Our study species, Meriania hernandoi (Melastomataceae), undergoes a floral shape change from pseudocampanulate corollas with more actinomorphically arranged stamens (first day) to open corollas with a more zygomorphic androecium (second day) over anthesis, providing a natural experiment to test how variation in floral shape affects pollination performance. Methods In one population of M. hernandoi, we bagged 51 pre-anthetic flowers and exposed half of them to bee pollinators when they were in either stage of their shape transition. We then collected flowers, obtained 3D flower models through x-ray computed tomography for 3D geometric morphometric analyses, and counted the pollen grains remaining per stamen (male pollination performance) and stigmatic pollen loads (female pollination performance). Results Male pollination performance was significantly higher in open flowers with zygomorphic androecia than in pseudo-campanulate flowers. Female pollination performance did not differ among floral shapes. Conclusions These results suggest that there is an ?optimal? shape for male pollination performance, while the movement of bees around the flower when buzzing the spread-out stamens results in sufficient pollen deposition regardless of floral shape.

Department für Botanik und Biodiversitätsforschung, Department für Funktionelle und Evolutionäre Ökologie, Department für Evolutionsbiologie
Externe Organisation(en)
Instituto Nacional de Biodiversidad
American journal of botany
Anzahl der Seiten
ÖFOS 2012
106008 Botanik, 106012 Evolutionsforschung, 106042 Systematische Botanik
ASJC Scopus Sachgebiete
Genetics, Ecology, Evolution, Behavior and Systematics, Plant Science
Link zum Portal