Honest floral signaling traits vary across and within populations in a
generalist-pollinated plant
Abstract
In flowering plants that produce concealed rewards, pollinator foraging
preferences may select for traits that are correlated with rewards. We
tested for variation in, and selection on, honest signals across and
within populations and mating systems in Arabis alpina. In a
greenhouse common garden, we tested for correlations between corolla
area, floral scent, and nectar volume in 29 populations. In 12 field
populations, we estimated pollen limitation and pollinator-mediated
selection on corolla area. Across and within populations and mating
systems, larger flowers generally produced more nectar. Total scent
emission was not correlated with nectar production, but two
compounds—phenylacetaldehyde and benzyl alcohol—may be honest
signals in some populations. Corolla area was not under contemporary
selection and was correlated with pollen limitation only across
populations. Our results suggest that honest signals may be similar
across populations but may not result from contemporary direct selection
on floral advertisements.