Data and code for "Beyond predators: carnivores as secondary dispersers of mycorrhizal fungi"

Animals are critical dispersers of plant and fungal propagules. Endozoochory, or primary dispersal, has been well documented for a wide range of plant and fungal taxa. However, trophic interactions can alter dispersal dynamics and growing evidence suggests that diploendozoochory (hereafter secondary dispersal) — where propagules are ingested by a primary consumer which in turn is predated upon by a secondary consumer, represents an important, yet understudied dispersal mechanism. This is especially true of mycorrhizal fungi, which often rely on small mammals (key food source for many predators) to consume and disperse spores. We investigated how predator size, diet, and movement influences secondary fungal 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 distance (dispersal quality). We quantified diet for five carnivore species that range in body mass by nearly and order of magnitude and tracked their interactions with 32 fungal taxa in the upper midwestern USA. We combined microscopy and sequencing of fungal spores with diet analysis to determine how consumption of small mammals relates to fungal spore composition in carnivore scats. Additionally, we incorporated movement rates and gut passage time of carnivores to predict the distance over which each carnivore species disperses spores. Spores in carnivore scats increased with consumption of small mammals and movement of spores closely tracked home range movements. Overall, larger carnivores deposited fewer spores but moved them farther from their source, creating a continuum between the quantity and quality of secondary dispersal effectiveness. Our findings highlight that carnivores are important long-distance dispersers of mycorrhizal fungi and reveal how trophic interactions contribute to ecosystem functioning through secondary dispersal.