Alpine ecosystems are characterized by a very high diversity of flowering plants. Recently, a significant discrepancy between flower color vision by human eyes versus pollinator eyes has been revealed. There is an enormous interest in exploring the eco-evolutionary relationship between a plant species’ flower color and its pollinating vector vision. The fundamental question is, how pollinators see plant community patterns in alpine ecosystems, especially in species-rich grasslands.
We have surveyed a total of 315 flowering plant species from calcareous and siliceous, subalpine and alpine grassland sites in the European Alps including: Brunnenkopf (1500 m asl, 203 species), Obergurgl (1900 – 2600 m, 99 species), Kaserstatt Stubai(1850 m, 138 species), Arnspitze (1700m, 107species) and Furka (2400 m, 116 species)
We collected petals of all locally occurring flowering plant species and measured their light reflectance property using ocean optics spectrophotometer. We used the ‘bumblebee color vision model’. This is because Hymenoptera vision is phylogenetically conserved since its evolution, and bumblebees are representative insect pollinators from low to high elevation in the European Alps. Although in human vision white, yellow, pink and purple colors dominate in the European alpine flora, we, here, present alternative insights of hymenopteran (bee) vision.
Results/Conclusions
Our data suggest that the flower colors in alpine grassland environments fall into the most well-known bee color space: blue, bluegreen, and green. Interestingly, all the white flowers in human vision fall into ‘bluegreen’ in bee vision, where all the yellow flowers fall into ‘uv-green, green and bluegreen’.
< ! Across an altitudinal gradient this discrepancy between human and pollinator vision increases with elevation. For human eyes 'white’ and yellow’ flowering plant species increase with higher elevation, whereas for bee eyes ‘blue’ and ‘green’ flowering species increase.
< ! Calcareous grasslands have a higher color diversity based on human vison and a higher number of blue and bluegreen flowers based on Hymenoptera vision than siliceous grasslands.
< ! Subalpine area shows a higher color diversity based on human vision, despite alpine regions harboring a higher number of plant species. Based on pollinator vision, more species with blue and bluegreen color occurs in the alpine than in subalpine region.
Dyer AG, Jentsch A, Burd M, Garcia JE, Giejsztowt J, Camargo MGG, Tjørve E, Tjørve KMC, White PS, Shrestha M (2021): Fragmentary blue: Resolving the rarity paradox in flower colours. Frontiers in Plant Science. doi: 10.3389/fpls.2020.618203
