title: Baleen whales host a unique gut microbiome with similarities to both carnivores and herbivores.
abstract: Mammals host gut microbiomes of immense physiological consequence, but the determinants of diversity in these communities remain poorly understood. Diet appears to be the dominant factor, but host phylogeny also seems to be an important, if unpredictable, correlate. Here we show that baleen whales, which prey on animals (fish and crustaceans), harbor unique gut microbiomes with surprising parallels in functional capacity and higher level taxonomy to those of terrestrial herbivores. These similarities likely reflect a shared role for fermentative metabolisms despite a shift in primary carbon sources from plant-derived to animal-derived polysaccharides, such as chitin. In contrast, protein catabolism and essential amino acid synthesis pathways in baleen whale microbiomes more closely resemble those of terrestrial carnivores. Our results demonstrate that functional attributes of the microbiome can vary independently even given an animal-derived diet, illustrating how diet and evolutionary history combine to shape microbial diversity in the mammalian gut.
authors.affiliation: Department of Organismic and Evolutionary Biology, Harvard University, 16 Divinity Avenue room 3085, Cambridge, Massachusetts 02138, USA.
authors.forename: Jon G
authors.identifier: http://orcid.org/0000-0001-6077-4014
authors.initials: JG
authors.lastname: Sanders
authors.affiliation: Department of Ecology and Evolutionary Biology, University of California, Los Angeles, 610 Charles Young Drive South, Los Angeles, California 90095, USA.
authors.forename: Annabel C
authors.initials: AC
authors.lastname: Beichman
authors.affiliation: Department of Organismic and Evolutionary Biology, Harvard University, 16 Divinity Avenue room 3085, Cambridge, Massachusetts 02138, USA.|Gund Institute for Ecological Economics, University of Vermont, 617 Main Street, Burlington, Vermont 05405, USA.
authors.forename: Joe
authors.initials: J
authors.lastname: Roman
authors.affiliation: Bigelow Laboratory for Ocean Sciences, 60 Bigelow Drive, East Boothbay, Maine 04544, USA.
authors.forename: Jarrod J
authors.initials: JJ
authors.lastname: Scott
authors.affiliation: Bigelow Laboratory for Ocean Sciences, 60 Bigelow Drive, East Boothbay, Maine 04544, USA.
authors.forename: David
authors.initials: D
authors.lastname: Emerson
authors.affiliation: Department of Organismic and Evolutionary Biology, Harvard University, 16 Divinity Avenue room 3085, Cambridge, Massachusetts 02138, USA.
authors.forename: James J
authors.initials: JJ
authors.lastname: McCarthy
authors.affiliation: Department of Organismic and Evolutionary Biology, Harvard University, 16 Divinity Avenue room 3085, Cambridge, Massachusetts 02138, USA.
authors.forename: Peter R
authors.initials: PR
authors.lastname: Girguis
mesh_terms: D000818:Animals; D060435:Carnivory; D005243:Feces / Q000382:microbiology; D005285:Fermentation; D000069196:Gastrointestinal Microbiome; D005798:Genes, Bacterial; D060434:Herbivory; D056186:Metagenomics; D012336:RNA, Ribosomal, 16S / Q000737:chemistry*; D014907:Whales / Q000382:microbiology*
chemical_list: D012336:RNA, Ribosomal, 16S