Co-Flowering Community Effects on the Evolutionary Ecology of two Orchid Species | Effekter av samblommande växtsamhällen på den evolutionära ekologin hos två orkidéarter

Pollinators play a fundamental role in the reproduction of most flowering plants and act as drivers of evolution through selection on floral traits, alongside other biotic and abiotic factors. Increasing studies highlight the importance of interactions between co-flowering species mediated by shared pollinators for plant reproduction, but their role in shaping patterns of selection remains understudied. This study quantified the targets of selection in a natural population of the rewarding orchids Gymnadenia conopsea and Platanthera bifolia and investigated whether variation in their co-flowering communities influenced pollination success, reproductive fitness, and selection patterns. The analyses included phenotypic traits related to pollinator attraction (plant height and flower number), and pollinator fit (spur length and width), as well as the composition of the co-flowering species communities. Phenotypic selection was estimated through pollination and female reproductive success by using multiple regression models and a dimension reduction approach on the co-flowering communities. Selection favored taller plants with more flowers through pollination success and reproductive fitness, while flowers with wider spurs were linked to higher reproductive fitness. The co-flowering community composition influenced pollination success stronger than reproductive fitness, indicating that community interactions are most important during initial pollination dynamics, while other factors like resource availability or herbivory likely influence final reproductive outcomes. Despite these effects, variation in the co-flowering communities did not alter patterns of selection. These findings highlight the complex interplay between floral traits, co-flowering species, and abiotic factors in shaping pollination, plant reproduction and phenotypic selection, which should be explored in future studies.