Interactions between seed-dispersing ant species affect plant community composition in field mesocosms

1. In generalized mutualisms, species vary in the quality of services they provide to their partners directly via traits that affect partner fitness and indirectly via traits that influence interactions with mutualist species that play similar functional roles. Myrmecochory, or seed dispersal by ants, is a generalized mutualism with ant species varying in the quality of dispersal services they provide to their plant partners. Variation in ant species identity can directly impact seed dispersal patterns and plant community composition; however, we know less about how interactions among seed-dispersing ant species indirectly influence plant partners.

2. The invasive ant, Myrmica rubra, is a high-quality seed-disperser in its native range and interacts with myrmecochores (ant-dispersed plants) and the high-quality seed disperser Aphaenogaster sp. in its invaded range. We use this system to examine how interactions between two functionally similar mutualist ant species influence the recr...