PARENT SESSION
Oral Session # 34: Plant Ecology II: Pollination and Dispersal.
Presiding: A McEuen
Tuesday, August 5. 1:30 PM to 5:00 PM, SITCC Meeting Room 202.

The effects of five ant species on the germination of Datura wrightii.

Marussich, Wendy^*,1, ¹ wendy.marussich@asu.edu, Tempe, AZ

ABSTRACT- Myrmecochory, or seed dispersal by ants, is often mediated by the presence a lipid-rich appendage, or elaiosome, on a seed. Typically, ants gather seeds, carry them to the nest, consume the elaiosome, and discard the seeds unharmed either in the nest or refuse pile. The benefit to the ants is presumably the nutritional content of the elaiosome, whereas benefits to the plant includes dispersal from the parent plant, protection from predators, reduced seedling competition, protection from fire, transportation to nutrient-rich microsites, and enhanced germination due to seed scarification. I tested whether seed scarification by ants enhances the germination of Datura wrightii by presenting D. wrightii seeds to field colonies of five ant species (Pogonomyrmex rugosus, P. californicus, P. maricopa/occidentalis, Aphaenogaster cockerelli, and Messor pergandei) and conducting a germination experiment with the seeds collected from the refuse piles of the ant colonies. I also measured the percent of seeds destroyed by the different ant species and the percent of missing seeds. Ant species did not affect number of days to germination, plant height, or number of leaves per plant. However, the total number of seeds germinated differed among ant species. Pogonomyrmex maricopa/occidentalis enhanced germination, whereas Messor pergandei most severely reduced germination rates. Benefits from scarification by ants do not explain the presence of elaiosomes in Datura wrightii. The reciprocal effects of ants and plants are explored with a mathematical model of seed fates.

Key words: Datura, ants, myrmecochory, seed dispersal