Bees, birds and yellow flowers

This video is called Louie Schwartzberg: The hidden beauty of pollination.

Bees, birds and yellow flowers: Pollinator-dependent convergent evolution of UV-patterns

Abstract

Colour is one of the most obvious advertisements of flowers and occurs in a huge diversity among the angiosperms. Flower colour is responsible for the attraction from a distance, whereas contrasting colour patterns within flowers aid orientation of flower-visitors after approaching the flowers. Due to the striking differences in colour vision systems and neural processing across animal taxa, flower colours evoke specific behavioural responses by different flower-visitors. We tested whether and how yellow flowers differ in their spectral reflectance depending on the main pollinator. We focused on bees and birds and examined whether the presence or absence of the widespread UV-reflectance pattern of yellow flowers predicts the main pollinator.

Most bee-pollinated flowers displayed a pattern with UV-absorbing centres and UV-reflecting peripheries, whereas the majority of bird-pollinated flowers are entirely UV-absorbing. In choice experiments we found that bees did not show consistent preferences for any colour- or pattern-types. However, all tested bee species made their first antennal contact preferably at the UV-absorbing area of the artificial flower irrespective of its spatial position within the flower. The appearance of UV-patterns within flowers is the main difference in spectral reflectance between yellow bee- and bird-pollinated flowers, and affects the foraging behaviour of flower-visitors. The results support the hypothesis that flower colours and the visual capabilities of their efficient pollinators are adapted to each other.