Characterizing each step of pollination in the wildflower, Phlox drummondii, reveals a single butterfly species predominates in the pollinator assemblage

Premise: A central goal of pollination biology is to connect plants with the identity of their pollinator(s). While predictions based on floral syndrome traits are extremely useful, direct observation can reveal further details of a species’ pollination biology. The wildflower, Phlox drummondii, has a floral syndrome consistent with pollination by a variety of lepidoptera. We describe pollination in P. drummondii and use empirical data to test this prediction.
Methods: We directly observe each step of the pollination process in P. drummondii. First, we observe 55.5 hours of floral visitation throughout the day/evening (7:00-20:30) at sites across the species range. We use a temporal pollinator exclusion experiment to determine the contribution of diurnal and nocturnal pollination to reproductive output. We then quantify P. drummondii pollen pickup and deposition by the dominant floral visitor, Battus philenor. Finally, we test the effect of B. philenor visitation on P. drummondii reprod..., Study species: P. drummondii (Polemoniaceae) is an annual herb native to central Texas that occurs along roadsides, fields, and pastures. Seeds germinate in early spring and individuals flower and fruit from April through June. Flowers are radially symmetric with a diameter of 18 to 24mm (Figure 1A,B) (Wherry 1955). Floral buds open in the morning (07:00-9:00) in both field and greenhouse conditions. If unpollinated, open flowers last approximately 2-4 days before wilting. Fruits begin developing 1-2 days after pollination and each flower can produce a single fruit. P. drummondii has an active self-incompatibility system and displays low rates of autonomous selfing (~1%) (Roda and Hopkins 2019).
Previous studies within the Phlox genus demonstrate visitation by a broad group of lepidopteran pollinators (Strakosh and Ferguson 2005; Wiggam and Ferguson 2005). Like other members of its genus, P. drummondii exhibits floral traits consistent with a lepidopteran pollination syndrome (Faegri an...,