Beyond Predators: Carnivores as Secondary Dispersers of Mycorrhizal Fungi

Abstract

Primary dispersers of seeds and spores play critical roles in structuring the distributions of species, yet the role of predators as secondary dispersers remains largely unknown. This is especially true of mycorrhizal fungi, which often rely on small mammals to consume and disperse spores. We investigated how predator size, diet, and movement influence secondary spore dispersal in a terrestrial carnivore community by quantifying spore loads in scats (dispersal quantity) and integrating movement rates with gut passage time to determine dispersal distance (dispersal quality). Spores in carnivore scats increased with consumption of small mammals and transport of spores closely tracked home range movements. Larger carnivores deposited fewer spores but moved them farther from their source, creating a continuum between the quantity and quality of dispersal effectiveness. Our findings highlight the importance of carnivores as long-distance dispersers of mycorrhizal fungi and reveal how trophic interactions contribute to ecosystem functioning through secondary dispersal.

Keywords: carnivore ecology; diploendozoochory; dispersal effectiveness; fungal dispersal; indirect dispersal; secondary dispersal.