The Coastal Coral Tree (Erythrina caffra Thunb.) produces floral nectar (FN) that serves to attract pollinating insects, but also secretes nectar from extra-floral (EFN) glands that serves to at-tract predatory insects, such as ants. While stu-dies on myrmecophytes (i.e. specialized plants that attract and interact with ants) have primarily focused on interspecific evaluations of EFN chemistry, the Coastal Coral tree offers an op-portunity to contrast intraspecific nectar chemi-stry with differing evolutionary and ecological functions. We hypothesized that the richness of (molecular) sugar species, relative concentra-tions, and diversity of sugars in FN and foliar EFN would diverge due to differences in the ecological role of the two types of nectar. High performance liquid chromatography with refrac-tive index detection was used to identify the richness of sugar species (based on retention time), measure the relative concentrations, and evaluate the diversity of sugars in FN and foliar EFN secretions. We detected sugar species unique to each gland type and reported signifi-cant differences in the relative concentration of one sugar species common to both gland types. While the mean diversity index of sugars was similar for both gland types, the diversity of fo-liar EFN sugars was significantly more variable than that of FN sugars. The composition of FN showed little variation, and was reflective of its fundamental role in plant reproduction. Foliar EFN, however, demonstrated the variability ex-pected of a context-dependent myrmecophyte that interacts with a facultative ant species as-semblage across a mosaic of abiotic and biotic conditions.
Copyright © 2014 Vіctor D. Carmona-Galindo et al.
Carmona-Galindo, V., K. Morales, R. Maser, J. Doyle, and M. Gobrial (2014). Characterization of sugar diversity in floral and extra-floral nectar from the coastal coral tree (Erythrina caffra Thunb.) in southern California. Open Journal of Ecology 4(2): 23-27.