Spatial variation in pollinator-mediated selection (Δβpoll) is a major driver of floral diversification, but we lack a quantitative understanding of its link to pollen limitation and net selection on floral traits. For 2-5 years, we quantified Δβpoll on floral traits in two populations each of two orchid species differing in pollen limitation. In both species, spatio-temporal variation in Δβpoll explained much of the variation in net selection. Selection was consistently stronger and the proportion that was pollinator-mediated was higher in the severely pollen-limited deceptive species than in the rewarding species. Within species, variation in pollen limitation could not explain variation in Δβpoll for any trait, indicating that factors in...