Pollen morphological evolution in bat pollinated plants

Abstract

This study assesses to what extent bat pollination has acted as a selective force on pollen morphology. Earlier pollen studies have suggested convergent evolution of verrucate exine ornamentation. Furthermore pollen of bat pollinated plants has been reported to be bigger than that of plants pollinated by other means. The generality of these ideas is tested using a sample of 130 species of both bat pollinated plants and relatives with another mode of pollination. An analysis of pollen size, shape, aperture number and type, and ornamentation type of 35 plant groups in which a transition towards bat pollination occurred was performed and showed a significant effect for pollen size only. Bat pollinated plants have bigger pollen than their relatives. Pollen size was shown to correlate with style length. Pollen shape, aperture system and exine ornamentation are in general not very different in bat pollinated plants in comparison with their relatives. There is no consistent trend for rougher exines to be associated with bat pollination.