A Caltech Library Service

Body mass predicts isotope enrichment in herbivorous mammals

Tejada-Lara, Julia V. and MacFadden, Bruce J. and Bermudez, Lizette and Rojas, Gianmarco and Salas-Gismondi, Rodolfo and Flynn, John J. (2018) Body mass predicts isotope enrichment in herbivorous mammals. Proceedings of the Royal Society of London. Series B, Biological Sciences, 285 (1881). Art. No. 20181020. ISSN 0962-8452. PMCID PMC6030519. doi:10.1098/rspb.2018.1020.

[img] PDF - Published Version
Creative Commons Attribution.

[img] PDF - Supplemental Material
Creative Commons Attribution.


Use this Persistent URL to link to this item:


Carbon isotopic signatures recorded in vertebrate tissues derive from ingested food and thus reflect ecologies and ecosystems. For almost two decades, most carbon isotope-based ecological interpretations of extant and extinct herbivorous mammals have used a single diet–bioapatite enrichment value (14‰). Assuming this single value applies to all herbivorous mammals, from tiny monkeys to giant elephants, it overlooks potential effects of distinct physiological and metabolic processes on carbon fractionation. By analysing a never before assessed herbivorous group spanning a broad range of body masses—sloths—we discovered considerable variation in diet–bioapatite δ¹³C enrichment among mammals. Statistical tests (ordinary least squares, quantile, robust regressions, Akaike information criterion model tests) document independence from phylogeny, and a previously unrecognized strong and significant correlation of δ¹³C enrichment with body mass for all mammalian herbivores. A single-factor body mass model outperforms all other single-factor or more complex combinatorial models evaluated, including for physiological variables (metabolic rate and body temperature proxies), and indicates that body mass alone predicts δ¹³C enrichment. These analyses, spanning more than 5 orders of magnitude of body sizes, yield a size-dependent prediction of isotopic enrichment across Mammalia and for distinct digestive physiologies, permitting reconstruction of foregut versus hindgut fermentation for fossils and refined mean annual palaeoprecipitation estimates based on δ¹³C of mammalian bioapatite.

Item Type:Article
Related URLs:
URLURL TypeDescription CentralArticle Information
Tejada-Lara, Julia V.0000-0003-2307-6764
MacFadden, Bruce J.0000-0002-4998-7083
Salas-Gismondi, Rodolfo0000-0001-9990-8841
Additional Information:© 2018 The Authors. Published by the Royal Society under the terms of the Creative Commons Attribution License, which permits unrestricted use, provided the original author and source are credited. Manuscript received 09/05/2018. Manuscript accepted 31/05/2018. Published online 27/06/2018. We are indebted to Enrique Cabrejo and all the Huachipa Zoo staff (especially M. Tello) for help during sample collection; to C. Pugh, L. Killmar, R. Ball and H. Henry from the Lowry Park Zoo (Tampa, Florida) for providing one Choloepus skull; and to Doug Jones for facilitating connections with that zoo. Thanks are expressed to John Krigbaum for collagen extraction of Pleistocene sloths. B. Passey kindly provided body mass data from the Passey et al. [6] study for regression analyses. We are grateful to ‘IsoPopes’ (IsoCamp 2016, 2017), especially T. Cerling and J. Ehleringer, for advice and stimulating discussions about isotopes. M. Reguero, K. Lyons and S. McLeod generously provided access to fossil specimens under their care. B. Linsley, S. Hemming, B. Honisch and R. MacPhee provided comments on an early version of the manuscript, and we appreciate suggestions from Carlos Martinez del Rio and two anonymous reviewers. We also thank J. Curtis and G. Kamenov for MS and REE analyses, respectively; J. Denton, J. Herrera and M. Ingala for assistance with computer programming; and Prof. editors L. Kruuk and J. Hutchinson for their handling of our manuscript. Analyses were carried out with funds from the Florida Museum of Natural History and the PCP-PIRE project (NSF PIRE 0966884). Additional funds from Columbia University GSAS and the American Museum of Natural History (Division of Paleontology Frick Fund and RGGS) covered some internal expenses during the writing stage of this project. Authors' Contributions. J.V.T.-L. and B.J.M. designed the initial study and oversaw isotope measurements. L.B and G.R. collected sloth samples. J.V.T.-L., R.S.-G., B.J.M. and J.J.F. analysed and interpreted data. J.V.T-.L. wrote the paper and all the authors contributed to manuscript preparation, provided comments on the manuscript and revised the manuscript in light of reviewer suggestions. Data accessibility. All data supporting this manuscript are available in the electronic supplementary material. We declare we have no competing interests.
Funding AgencyGrant Number
Florida Museum of Natural HistoryUNSPECIFIED
Columbia UniversityUNSPECIFIED
American Museum of Natural HistoryUNSPECIFIED
Issue or Number:1881
PubMed Central ID:PMC6030519
Record Number:CaltechAUTHORS:20220810-751623000
Persistent URL:
Official Citation:Tejada-Lara Julia V., MacFadden Bruce J., Bermudez Lizette, Rojas Gianmarco, Salas-Gismondi Rodolfo and Flynn John J. 2018. Body mass predicts isotope enrichment in herbivorous mammals. Proc. R. Soc. B. 2852018102020181020;
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:116205
Deposited By: George Porter
Deposited On:11 Aug 2022 18:17
Last Modified:11 Aug 2022 18:17

Repository Staff Only: item control page