Data from: Selection on floral design in Polemonium brandegeei (Polemoniaceae): female and male fitness under hawkmoth pollination

Plant-pollinator interactions promote the evolution of floral traits that
attract pollinators and facilitate efficient pollen transfer. The spatial
separation of sex-organs, herkogamy, is believed to limit sexual
interference in hermaphrodite flowers. Reverse herkogamy (stigma recessed
below anthers) and long narrow corolla-tubes are expected to promote
efficiency in male function under hawkmoth pollination. We tested this
prediction by measuring selection in six experimental arrays of Polemonium
brandegeei, a species that displays continuous variation in herkogamy,
resulting in a range of recessed to exserted stigmas. Under glasshouse
conditions, we measured pollen removal and deposition, and estimated
selection gradients (ß) through female fitness (seeds set) and male
fitness (siring success based on 6 polymorphic microsatellite loci).
Siring success was higher in plants with more nectar sugar and narrow
corolla-tubes. However, selection through female function for reverse
herkogamy was considerably stronger than was selection through male
function. Hawkmoths were initially attracted to larger flowers, but
overall preferred plants with reverse herkogamy. Greater pollen deposition
and seed set also occurred in reverse herkogamous plants. Thus, reverse
herkogamy may be maintained by hawkmoths through female rather than male
function. Further, our results suggest that pollinator attraction may play
a considerable role in enhancing female function.