Data from: Dissecting pollinator responses to a ubiquitous ultraviolet floral pattern in the wild
Koski, Matthew H.; Ashman, Tia-Lynn (2014), Data from: Dissecting pollinator responses to a ubiquitous ultraviolet floral pattern in the wild, Dryad, Dataset, https://doi.org/10.5061/dryad.bm558
1. Color patterns on flowers can increase pollinator visitation and enhance foraging behavior. Flowers uniform in color to humans, however, can appear patterned to insects due to spatial variation in UV-reflectance on petals. A UV ‘bullseye’ pattern that is common among angiosperms—UV-absorbing petal bases and reflective apices—purportedly functions as a nectar guide, enhancing pollinator orientation, and experimental evidence suggests that UV reflectance increases apparency to pollinators. 2. We test the pollinator-attracting and -orienting functions of floral UV pattern and UV reflectance under natural conditions. Specifically, we address whether UV reflection alone, or UV pattern influences small bee and syrphid fly attraction rates (approaching, landing, and foraging visits), foraging rates, and likelihood of foraging and orienting to the center of flowers, using Argentina anserina, a species whose flowers exhibit variability in the size of the UV bullseye. We manipulated UV properties while maintaining uniformly yellow petals to create three phenotypes—uniformly UV-absorptive, uniformly UV-reflective, and inversed bullseye (reflective bases, absorptive apices) and compared insect visitation and behavior to control flowers with the common UV bullseye phenotype. 3. The presence of UV pattern increased attraction rates by both bees and syrphid flies relative to either fully UV reflective or absorptive flowers. However, only in the inverse array, did the bullseye phenotype elicit higher foraging rates than the test flower. Neither the presence of pattern, nor the reversal of the common pattern influenced the likelihood of pollinator foraging or orientating to the flowers’ center during a visit. 4. We provide some of the first evidence to suggest that flowers with spatial variation in UV reflectance may be more conspicuous to insects than those with petals that uniformly absorb or reflect UV, all of which are naturally occurring phenotypes. Further, we verify that the most common UV pattern in nature increases insect attraction and foraging rate relative to the inverse pattern. Results confirm a distance apparency function of the UV bullseye, but we argue for reconsideration of the notion that pollinators benefit from this ubiquitous floral motif through enhanced foraging efficiency.