Reciprocal facilitation between ants and small mammals in tidal marshes

CANEPUCCIA, ALEJANDRO; HIDALGO, FERNANDO J; FANJUL, EUGENIA; IRIBARNE, OSCAR

Oecologia

Springer Science and Business Media Deutschland GmbH

Año: 2024 vol. 204 p. 575 - 588

The role of facilitation in shaping natural communities has primarilybeen studied in the context of plant assemblages, while its relevancefor mobile animals remains less understood. Our study investigateswhether reciprocal interspecific facilitation may exist between fireants (Solenopsis richteri) and cavies (Cavia aperea), two mobileanimals, in the SW Atlantic coast brackish marshes. Field samplesshowed a spatial association between ant mounds and cavies, and tatants prefer to use cavy runways for movement within the marsh.Through experiments involving transplanting the dominant plant,cordgrass (Spartina densiflora), and manipulating cavy presence inareas with and without ant mounds, we observed that cavies forageextensively (and defecate more) near ant mounds. The ants activelyremove cavy droppings in their mound vicinity. These ant activitiesand interactions with cavy droppings led to reduced moisture andorganic content while increasing nitrate and phosphate levels inmarsh sediment. Consequently, this enhanced plant growth, indirectlyfacilitating the cavies, which preferred consuming vegetation nearant mounds. These cascading indirect effects persisted over time;even four months after cavies left the marshes, transplanted plantsnear ant mounds remained larger and exhibited more leaf senescencewhen exposed to cavy herbivory. Therefore, the networks of positiveinteractions appear to generate simultaneous selection among species(populations), promoting coexistence within the community. Althoughcomplex, these reciprocal facilitative effects among mobile animalsmay be more common than currently believed and should be furtherstudied to gain a better understanding of the underlying mechanismsdriving species coexistence in natural communities.p { line-height: 115%; margin-bottom: 0.25cm; background: transparent }