Diet components associated with specific bacterial taxa shape overall gut community compositions in omnivorous African viverrids.

Gut bacterial communities provide flexibility to hosts during dietary changes. Despite the increasing number of studies exploring the associations between broader dietary guilds of mammalian hosts and their gut bacteria, it is generally unclear how diversity and variability in consumed diets link to gut bacterial taxa in wild non-primate mammals, particularly in omnivores. Here, we contribute to filling this gap by exploring consumed diets and gut bacterial community compositions with metabarcoding of faecal samples for two African mammals, Civettictis civetta and Genetta spp., from the family Viverridae. For each individual sample, we characterised bacterial communities and identified dietary taxa by sequencing vertebrate, invertebrate and plant markers. This led us to establish diet compositions that diverged from what has previously been found from visual identification methods. Specifically, while the two genera have been categorised into the same dietary guild, we detected more animal dietary items than plant items in C. civetta, while in Genetta spp., we observed the opposite. We further found that individuals with similar diets have similar gut bacterial communities within both genera. This association tended to be driven by specific links between dietary items and gut bacterial genera, rather than communities as a whole, implying diet-driven selection for specific gut microbes in individual wild hosts. Our findings underline the importance of molecular tools for improving characterisations of omnivorous mammalian diets and highlight the opportunities for simultaneously disentangling links between diets and gut symbionts. Such insights can inform robustness and flexibility in host-microbe symbioses to dietary change associated with seasonal and habitat changes.

Frightened of giants: fear responses to elephants approach that of predators.

Animals are faced with a variety of dangers or threats, which are increasing in frequency with ongoing environmental change. While our understanding of fearfulness of such dangers is growing in the context of predation and parasitism risk, the extent to which non-trophic, interspecific dangers elicit fear in animals remains less appreciated. We provide an experimental test for fear responses of savannah ungulates to a dominant and aggressive megaherbivore, the African bush elephant (Loxodonta africana), and contrast responses to an apex predator known to elicit fear in this system. Using an automated behavioural response system, we contrast vigilance and run responses of ungulates to elephant, leopard (Panthera pardus), and control (red-chested cuckoo Cuculus solitarius) vocalizations. Overall, we find that ungulates responded to elephant calls, both in terms of an increase in run and vigilance responses relative to controls. The magnitude of most behavioural responses (four of six considered) to elephant vocalizations were not significantly different than responses to leopards. These results suggest that megaherbivores can elicit strong non-trophic fear responses by ungulates and call to broaden frameworks on fear to consider dominant species, such as megaherbivores, as key modifiers of fear-induced interactions.