Can The Carbon and Nitrogen Isotope Values of Offspring be Used as a Proxy for Their Mother's Diet? Using Foetal Physiology to Interpret Bulk Tissue and Amino Acid δ¹⁵N Values

Authors

Nico Lübcker
John P. Whiteman, Old Dominion UniversityFollow
Seth D. Newsome
Robert P. Millar
P.J. Nico de Bruyn

Document Type

Article

Publication Date

2020

DOI

10.1093/conphys/coaa060

Publication Title

Conservation Physiology

Volume

8

Issue

1

Pages

coaa060 (1-16)

Abstract

The measurement of bulk tissue nitrogen (δ¹⁵N) and carbon isotope values (δ¹³C) chronologically along biologically inert tissues sampled from offspring can provide a longitudinal record of their mothers' foraging habits. This study tested the important assumption that mother-offspring stable isotope values are positively and linearly correlated. In addition, any change in the mother-offspring bulk tissues and individual amino acids that occurred during gestation was investigated. Whiskers sampled from southern elephant seal pups (Mirounga leonina) and temporally overlapping whiskers from their mothers were analyzed. This included n = 1895 chronologically subsampled whisker segments for bulk tissue δ¹⁵N and δ¹³C in total and n = 20 whisker segments for amino acid δ¹⁵N values, sampled from recently weaned pups (n = 17), juvenile southern elephant seals (SES) < 2 years old (n = 23) and adult female SES (n = 17), which included nine mother-offspring pairs. In contrast to previous studies, the mother-offspring pairs were not in isotopic equilibrium or linearly correlated during gestation: the Δ¹⁵N and Δ¹³C mother-offspring offsets increased by 0.8 and 1.2‰, respectively, during gestation. The foetal bulk δ¹⁵N values were 1.7 ± 0.5‰ (0.9-2.7‰) higher than mothers' δ¹⁵N values before birth, while the foetal δ¹³C increased by ~1.7‰ during gestation and were 1.0 ± 0.5‰ (0.0-1.9‰) higher than their mothers' δ¹³C at the end of pregnancy. The mother-offspring serine and glycine Δ¹⁵N differed by ~4.3‰, while the foetal alanine δ¹⁵N values were 1.4‰ lower than that of their mothers during the third trimester of pregnancy. The observed mother-offspring δ¹⁵N differences are likely explained by shuttling of glutamate-glutamine and glycine-serine amongst skeletal muscle, liver, placenta and foetal tissue. Foetal development relies primarily on remobilized endogenous maternal proteinaceous sources. Researchers should consider foetal physiology when using offspring bulk tissue isotope values as biomarkers for the mother's isotopic composition as part of monitoring programmes.

Rights

Originally published in Conservation Physiology by Oxford University Press.

Publisher's version available at: https://doi.org/10.1093/conphys/coaa060

Data Availability

Article states: "Data will be made available on the Dryad Digital Repository."

Original Publication Citation

Lübcker, N., Whiteman, J. P., Newsome, S. D., Millar, R. P., & de Bruyn, P. J. N. (2020). Can the carbon and nitrogen isotope values of offspring be used as a proxy for their mother's diet? Using foetal physiology to interpret bulk tissue and amino acid δ¹⁵N values. Conservation Physiology, 8(1), 1-16, Article coaa060. https://doi.org/10.1093/conphys/coaa060

Repository Citation

Lübcker, Nico; Whiteman, John P.; Newsome, Seth D.; Millar, Robert P.; and Bruyn, P.J. Nico de, "Can The Carbon and Nitrogen Isotope Values of Offspring be Used as a Proxy for Their Mother's Diet? Using Foetal Physiology to Interpret Bulk Tissue and Amino Acid δ¹⁵N Values" (2020). Biological Sciences Faculty Publications. 411.
https://digitalcommons.odu.edu/biology_fac_pubs/411