Flower colour within communities shifts from overdispersed to clustered along an alpine altitudinal gradient
Altitudinal gradients are interesting models to test the effect of biotic and abiotic drivers of floral colour diversity, since an increase in UV irradiance, decrease of pollinator availability and shifts from bee- to fly-pollination in high relative to low altitudes are expected. We tested the effect of altitude and phylogeny, using several chromatic and achromatic colour properties, UV reflectance and pollinators’ discrimination capacity (Apis mellifera, Bombus terrestris, Musca domestica and Eristalis tenax), to understand the floral colour diversity in an alpine altitudinal gradient. All colour properties were weakly related to phylogeny. We found a shift from overdispersed floral colours and high chromatic contrast with the background (for bees) in the low altitude, to clustered floral colours (UV and green range for bees and flies) and clustered chromatic and achromatic properties in the high altitude. Different from flies, bees could discriminate floral colours in all altitudinal ranges. Low altitudes are likely to exhibit suitable conditions for more plant species, increasing competition for pollinators and floral colour divergence. Conversely, the increase in UV irradiance in high altitudes may filter plants with specific floral UV-reflectance patterns. Overall, floral colour diversity suggests that both biotic (pollinator fauna) and abiotic (UV irradiance) drivers shape floral communities, but their importance changes with altitude.
KeywordsCompetition Environmental filtering Facilitation Pollination ecology UV reflectance
PJB thanks the National Council for Scientific and Technological Development (CNPq, Grant 140254/2016-1) and São Paulo Research Foundation (FAPESP, Grant 2016/06434-0), FJT thanks the Coordination for the Improvement of Higher Education Personnel (CAPES-1659767) for the Postdoctoral grant (PNPD), VLGB thanks Minas Gerais State Agency for Research and Development (FAPEMIG, grant APQ-02497-16). The raw data collection for this manuscript was supported by a Leibniz Award from the DFG. SEJA’s previous analysis was carried out supported by the Biotechnology and Biological Sciences Research Council (BBSRC) CASE studentship in association with the Royal Botanic Gardens, Kew, BS/S/L/2005/12155A. We thank Prof. Dr. Klaus Lunau for providing spectral sensitivity of Eristalis tenax and helping with fly model calculations.
Author contribution statement
PJB, FJT and VLGB performed analyses. SEJA performed original analysis and processing of reflectance data. All authors conceived the study and contributed to the writing of the manuscript.
Compliance with ethical standards
Conflict of interest
The authors declare that they have no conflict of interest.
This article does not contain any studies with human participants or animals performed by any of the authors.
- Blomberg SP, Garland Jr T, Ives AR (2003) Testing for phylogenetic signal in comparative data: behavioral traits are more labile. Evolution 57:717–745. https://doi.org/10.1554/0014-3820(2003)057[0717:TFPSIC]2.0.CO;2Google Scholar
- Chittka L, Kevan PG (2005) Flower colour as advertisement. In: Dafni A, Kevan PG, Husband BC (eds) Practical pollination biology. Environquest Ltd., Cambridge, pp 157–196Google Scholar
- Gotelli NJ (2000) Null model analysis of species co-occurrence patterns. Ecology 81:2606–2621. https://doi.org/10.1890/0012-9658(2000)081[2606:NMAOSC]2.0.CO;2Google Scholar
- Ratchke B (1983) Competition and facilitation among plants for pollinators. In: Real L (ed) Pollination biology. Academic Press, New York, pp 309–329Google Scholar
- Valiente-Banuet A, Aizen MA, Alcántara JM, Arroyo J, Cocucci A, Galetti M, García MB, García D, Gómez JM, Jordano P, Medel R, Navarro L, Obeso JR, Oviedo R, Ramírez N, Rey PJ, Traveset A, Verdú M, Zamora R (2015) Beyond species loss: the extinction of ecological interactions in a changing world. Funct Ecol 29:299–307. https://doi.org/10.1111/1365-2435.12356 CrossRefGoogle Scholar
- Webb CO, Ackerly DD, McPeek MA, Donoghue MJ (2002) Phylogenies and community ecology. Annu Rev Ecol Syst 33:475–505. https://doi.org/10.1146/annurev.ecolsys.33.010802.150448 CrossRefGoogle Scholar
- Wyszecki G, Stiles WS (1982) Color science. Wiley, New YorkGoogle Scholar