Stable nitrogen and carbon isotope discrimination between juveniles and adults in an income-breeding small mammal (Peromyscus maniculatus)

Abstract

a b s t r a c tWe investigated the stable nitrogen-and carbon-isotope compositions of blood, liver, muscle and hair of income breeding deer mice (Peromyscus maniculatus) to determine the extent to which stable isotope compositions of mothers and offspring differed. We found small differences between the ␦ 15 N and ␦ 13 C values of dependent offspring and adult tissues (by a magnitude of −0.8‰ to 1.1‰ for 15 N and 0.3-0.9‰ for 13 C), and limited 15 N discrimination between juvenile tissues and milk, which explains the small mother-offspring trophic effects in isotopic composition. Discrimination of 15 N between offspring and adults was greater than expected but smaller than known for capital breeding mammals, suggesting that different biochemical pathways for milk production and processing may affect the discrimination of 15 N in these systems.

Milk isotopic values demonstrate that nursing fur seal pups are a full trophic level higher than their mothers

“…Indeed, ∆ 15 N values between whole blood and red blood cells of consumers and their diet average 3 ‰ in mammals, including pinnipeds (1.7–4.1 ‰). Surprisingly, however, the results are inconsistent with the real ∆ 15 N values obtained with other tissues, namely plasma/serum, hair and vibrissae, with all the values being less than a full trophic level . There is no obvious explanation for this discrepancy.…”

“…Indeed, milk of terrestrial mammals appears to be depleted in 15 N relative to maternal plasma, thus lowering apparent ∆ 15 N values between the plasma of nursing offspring and their mothers . The latter investigation is the largest one (10 species) among the few that quantify and compare real and apparent ∆ 15 N (and ∆ 13 C) values in animals held in controlled conditions (see also). A single study conducted in the wild showed little 15 N enrichment between milk and maternal serum (0.5 ‰) and slightly higher 15 N enrichment between milk and pup serum (1.0 ‰).…”

Discrimination factors of carbon and nitrogen stable isotopes from diet to hair in captive large Arctic carnivores of conservation concern

“…The Δ 15 N value in polar bear cubs was higher (M: 2.74 ± 0.21‰; F: 2.90 ± 0.21‰) than that reported in Rode et al and in our adult female. Mother‐offspring 15 N enrichment is typical in both capital and income mammalian breeders during lactation, with a fading trend during the weaning phase. The female polar bear that we studied was still providing milk to her two cubs, yet not in its prime lactating period (cubs of 1.5 years old are mostly weaned in captivity).…”

Stable carbon and nitrogen isotope trophic enrichment factors for Steller sea lion vibrissae relative to milk and fish/invertebrate diets

“…Mother−offspring isotopic comparisons of paired tissues are seldom made (but see Jenkins et al 2001, Dalerum et al 2007, Miller et al 2011, and this study represents only the second attempt for vibrissae . We have demonstrated that late gestation pup vibrissae were isotopi-cally enriched in 15 N relative to maternal vibrissae (TEF 1 ), ~0.9 ‰ for δ 15 N. The offset for δ 15 N is consistent with expectations for nursing animals (Jenkins et al 2001, Polischuk et al 2001, Stegall et al 2008, Habran et al 2010, Ben-David et al 2012) but lower than a full trophic step for carnivores (i.e.…”