Variation in ant-mediated seed dispersal along elevation gradients
Ant-mediated seed dispersal, also known as myrmecochory, is a widespread and important mutualism that structures both plant and insect communities. However the extent to which myrmecochory is driven by abiotic and biotic environmental factors remains unclear. We used a replicated standardized seed removal experiment along elevation gradients in four mountain ranges in the southwestern United States to test predictions that: (1) seed removal rates would be greater at lower elevations, and (2) seed species identity influences seed removal rates, (i.e. seeds from their native elevation range would be removed at higher rates than seeds outside of their range). Both predictions were supported. Seed removal rates were ~25% higher at lower elevation sites than at higher elevation sites. The low elevation Datura and high elevation Iris were removed at higher rates in their respective native ranges. We attribute observed differences in dispersal rates to changes in ant community composition, functional diversity, and abundance, suggesting that temperature variation along the elevation gradient.