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Venkataraman, Vivek

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Venkataraman

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Vivek

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Venkataraman, Vivek
Author's Publications: search.filters.isAuthorOfPublication.adaac449-0c86-46a6-bd9c-0f1ee1de7632

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    Competition between sympatric wolf taxa: an example involving African and Ethiopian wolves
    (The Royal Society Publishing, 2018) Gutema, Tariku Mekonnen; Atickem, Anagaw; Bekele, Afework; Sillero-Zubiri, Claudio; Kasso, Mohammed; Tsegaye, Diress; Venkataraman, Vivek; Fashing, Peter J.; Zinner, Dietmar; Stenseth, Nils C.
    Carnivore populations are declining globally due to range contraction, persecution and prey depletion. One consequence of these patterns is increased range and niche overlap with other carnivores, and thus an elevated potential for competitive exclusion. Here, we document competition between an endangered canid, the Ethiopian wolf (EW), and the newly discovered African wolf (AW) in central Ethiopia. The diet of the ecological specialist EW was dominated by rodents, whereas the AW consumed a more diverse diet also including insects and non-rodent mammals. EWs used predominantly intact habitat, whereas AWs used mostly areas disturbed by humans and their livestock. We observed 82 encounters between the two species, of which 94% were agonistic. The outcomes of agonistic encounters followed a territory-specific dominance pattern, with EWs dominating in intact habitat and AWs in human-disturbed areas. For AWs, the likelihood of winning encounters also increased with group size. Rodent species consumed by EWs were also available in the human-disturbed areas, suggesting that these areas could be suitable habitat for EWs if AWs were not present. Increasing human encroachment not only affects the prey base of EWs, but also may impact their survival by intensifying competition with sympatric AWs.
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    Multilevel social structure and diet shape the gut microbiota of the gelada monkey, the only grazing primate
    (BioMed Central, 2018) Trosvik, Pål; de Muinck, Eric J.; Rueness, Eli K.; Fashing, Peter J.; Beierschmitt, Evan C.; Callingham, Kadie R.; Kraus, Jacob B.; Trew, Thomas H.; Moges, Amera; Mekonnen, Addisu; Venkataraman, Vivek; Nguyen, Nga
    Background: The gelada monkey (Theropithecus gelada), endemic to the Ethiopian highlands, is the only graminivorous primate, i.e., it feeds mainly on grasses and sedges. In spite of known dental, manual, and locomotor adaptations, the intestinal anatomy of geladas is similar to that of other primates. We currently lack a clear understanding of the adaptations in digestive physiology necessary for this species to subsist on a graminoid-based diet, but digestion in other graminivores, such as ruminants, relies heavily on the microbial community residing in the gastrointestinal (GI) system. Furthermore, geladas form complex, multilevel societies, making them a suitable system for investigating links between sociality and the GI microbiota. Results: Here, we explore the gastrointestinal microbiota of gelada monkeys inhabiting an intact ecosystem and document how factors like multilevel social structure and seasonal changes in diet shape the GI microbiota. We compare the gelada GI microbiota to those of other primate species, reporting a gradient from geladas to herbivorous specialist monkeys to dietary generalist monkeys and lastly humans, the ultimate ecological generalists. We also compare the microbiotas of the gelada GI tract and the sheep rumen, finding that geladas are highly enriched for cellulolytic bacteria associated with ruminant digestion, relative to other primates. Conclusions: This study represents the first analysis of the gelada GI microbiota, providing insights into the adaptations underlying graminivory in a primate. Our results also highlight the role of social organization in structuring the GI microbiota within a society of wild animals. Electronic supplementary material The online version of this article (10.1186/s40168-018-0468-6) contains supplementary material, which is available to authorized users.