Removal rates of seeds adapted for dispersal by ants

Focused on seeds of 2 common ant-dispersed species in a field experiment in Kuringai Chase National Park, SE Australia. The most important influence on removal rate over the first 12 h of exposure was the precise location of seeds on the ground (54% of total variation). This variation did not persist over longer periods of time and, except during winter, all seeds had a high probability of being removed within 2-3 d. Time of year also had a strong influence on removal rate (21% of total variation) with the highest rates occurring in summer and the lowest in winter. These changes were mainly attributable to changes in ambient temperature. Difference in removal rates between the 2 seed species used was the 3rd most important source of variation (4%). There was significant variation ion removal rate between the same months in different years in 2 of 3 between-year comparisons. The effect of year, and of interactions between year and other factors, accounted for between 7-18% of total variation. Ants were the only important removers of seed. Seed age up to 1 yr did not influence removal rate. The high probability of removal of elaiosome-bearing seeds within 2-3 d of seedfall means it is unlikely that ant-dispersed plants in this vegetation ever face the problem of their seeds not being encountered and transported by an ant. The problem may be how to be removed by those ant species whose behaviour will give the seed the best change of survival and establishment. -from Authors