Color preference and spatial distribution of glaphyrid beetles suggest a key role in the maintenance of the color polymorphism in the peacock anemone (Anemone pavonina, Ranunculaceae) in Northern Greece
In the Mediterranean region, a group of unrelated plant species share an unusual deep-red flower color and are pollinated by glaphyrid beetles. Some of these species possess different color morphs, but the mechanisms maintaining this color polymorphism are unknown. The peacock anemone, Anemone pavonina, is a color polymorphic species with red or purple flowers. We investigated the spatial distribution of its color morphs and its potential glaphyrid pollinators, Pygopleurus spp., along an elevational gradient on the southern slopes of Mount Olympus, Greece. We found a correlation between relative proportions of the two color morphs with both elevation and beetle abundance. At low elevations (< 1000 m a.s.l.), beetles were abundant and anemone populations comprised only red flowers. Above a steep transition zone with mixed-colored populations (c. 1000–1300 m) most flowers were purple and beetles were rare. Color-trapping experiments revealed a strong preference for red over other colors in beetles and colorimetric modeling suggests that a simple chromatic mechanism is sufficient to explain their color choices. We thus hypothesize that beetles select for red flowers and that with increasing elevation and decreasing beetle density, other flower visitors (e.g., bees) gain importance as pollinators and select for a different color.
KeywordsBeetle pollination syndrome Color vision Elevational distribution Floral signal Red bowl-shaped flowers
We thank K. Stejskal and N. Sommer for help in the field, and J. Plant for linguistic improvement of the manuscript.
MS, HFP and JS conceived the experimental concept. MS, NR and JS performed the experiments. MS and NR analyzed the data. MS, NR and JS wrote a first version of the manuscript. All authors discussed the results, commented on the paper and agreed to the final version.
Compliance with ethical standards
Conflict of interest
The authors declare that they have no conflict of interest.
All applicable international, national, and/or institutional guidelines for the care and use of animals were followed.
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