COMPARATIVE CHEMISTRY OF ELAIOSOMES OF 3 SPECIES OF TRILLIUM

This study was designed to compare the chemistry of elaiosomes of three sympatric species of Trillium to discover if there are correlations between chemistry and dispersal rates by ants. We quantified the amount of proteins and neutral lipids and qualitatively analyzed the fatty acids occurring in triglyceride, diglyceride, monoglyceride, and free fatty acid fractions. T. grandiflorum had the highest lipid concentration per milligram of protein and the highest total lipid per elaiosome, followed by T. erectum and then by T. undulatum. Oleic acid (18:1) was abundant in all lipid fractions of each species. This fatty acid, which is responsible for corpse-carrying behavior in some ants, probably causes ants to pick up diaspores. Linoleic acid (18:2) is relatively abundant in T. erectum and T. grandiflorum but not in T. undulatum and may cause ants that have picked up diaspores to move (carry) those diaspores back to the nest. Total elaiosome mass and fatty acid composition appear to explain why T. erectum is dispersed most rapidly and why ants that have picked up elaiosomes move more T. grandiflorum than T. undulatum diaspores.