Signal honesty and cost of pollinator-rewards in Dalechampia

Most species of Dalechampia vines (Euphorbiaceae) attract bee pollinators with terpenoid resins secreted by a gland-like structure in the inflorescence. Pélabon et al. study the costs of resin production in D. scandens and find no evidence for a trade-off between resin and seed production. Instead, after correcting for blossom size, they find that plants producing more resin also produce larger seeds, as would be expected if both are dependent on growing conditions. They also find that gland size is a better indicator of the amount of reward than bract size, although the latter remains an honest signal of the quantity of resin produced.