Prevalence and consequences of heterospecific pollen receipt in the subalpine plant communities of <em>Polemonium brandegeei</em>

Many pollinators visit multiple plant species, causing pollinators to deposit diverse pollen loads. Although heterospecific pollen (HP) transfer is widespread, few studies have tested how HP deposition affects plant fitness in natural populations. We investigated the fitness consequences of HP receipt within two floral communities surrounding Polemonium brandegeei (Polemoniaceae), a subalpine herb with diverse pollinators. First, we collected open pollinated stigmas from abundant species in flower (n = 11) and generated pollen transfer networks. All sampled species received or donated HP with distantly related species. Positive relations between HP receipt and conspecific pollen (CP) number and germination indicated facilitation due to pollinator sharing in P. brandegeei and Harbouria trachypleura (Apiaceae); however, HP receipt was low and did not affect CP germination in most species. Second, we conducted hand pollinations to test how donor-recipient relatedness affected consequences ..., , README file for: pollenTrasferNetwork_CO-DM.csv pollenTrasferNetwork_WY-VD.csv Data from pollen loads observed on stigmas of four (CO-DM) and eight (WY-VD) species: pollen counts and identification. The \"species\" column identifies the species the stigma belongs to. Species codes are described in Table S1 and below. The \"stigmaID\" column identifies the unique stigma code. The \"germinatedCP\" column identifies the number of germinated conspecific pollen grains observed on the stigma. The \"CP\" column identifies the total amount of conspecific pollen grains observed on the stigma. The \"HP\" column identifies the total amount of heterospecific pollen grains observed on the stigma. The remaining columns identify the amount of heterospecific pollen grains of a specific species observed on the stigma. Species codes are described in Table S1 and below. Species codes are as follows: *Antennaria anaphaloides* (Aa) *Arctostaphylus uva-ursi* (Au) *Cerastium arvense* (Ca) *Drymocallis fissa* (Df) *...,