Geographically structured phenotypic selection can lead to adaptive divergence. However, in flowering plants, such divergent selection has rarely been shown, and selection on floral signals is generally little understood. In this study, we measured phenotypic selection on display size, floral color, and floral scent in four lowland and four mountain populations of the nectar-rewarding terrestrial orchid Gymnadenia odoratissima in two years. We also quantified population differences in these traits and pollinator community composition. Our results show positive selection on display size and positive, negative, or absence of selection on different scent compounds and floral color. Selection on the main scent compounds was consistently stronger in the lowlands than in the mountains, and lowland plants emitted higher amounts of most of these compounds. Pollinator community composition also differed between regions, suggesting different pollinators select for differences in floral volatiles. Overall, our study is the first to document consistent regional differences in selection on floral scent, suggesting this pattern of selection is one of the evolutionary forces contributing to regional divergence in floral chemical signaling.
Data__SelectionAnalysis
Data used for the selection analyses, including number of fruits, floral trait values, relative female reproductive success (RelfRS), standardised floral trait values (Z_...), and PC loadings for the two-year data set (PC1, PC2, ...) and for the one-year data set (PC1A, PC2A, ...). Data listed in an Excel sheet.
Data__PollinatorLimitation
Data used to estimate pollinator limitation and pollinator dependency in fruit production, including the number of flowers, the number of fruits, and the proportional female reproductive success (ProportionalfRS) for the plants assigned to the three treatments "open pollination", "hand pollination" and "pollinator exclusion". Data listed in an Excel sheet.
Data__PollinatorFamiliesPerH
Number of pollinator per hour in each population and on each date listed separately for each pollinator family/order calculated based on S6 Table. Data listed in an Excel sheet.
Data__NoPollinators_PollinatorFamilyRichness
Number of pollinators and pollinator family richness per h in each population and on each date calculated based on S6 Table. Data listed in an Excel sheet.
Data__FloralTraitDifferences
Data used to analyse differences in floral traits between regions, populations and years, including the original floral trait values and the ln(x + 1) transformed values used for the statistical analyses. Data listed in an Excel sheet.
Data__PhenotypicSelectionGradients
Excel sheet listing the phenotypic selection gradients and standard errors (SE) shown in Fig 2.
Data__ReproductiveSuccessDifferences
Data used to analyse differences in female reproductive success between regions and between populations, including the original data of the number of flowers, the number of fruits, and the proportional female reproductive success (ProportionalfRS) as well as the transformed data, which were used for the statistical analyses. Data listed in an Excel sheet.
Data__HerbivoryDifferences
Data used to analyse differences in herbivory between regions and between populations, including the number of flowers eaten per plant and aphid load. Data listed in an Excel sheet.