Bulk tissue versus amino acid carbon stable isotopes to reveal the diet and basal resource use of an invasive rodent
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2026
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| author | Wieteke A. Holthuijzen Daniel Simberloff |
| author_facet | Wieteke A. Holthuijzen Daniel Simberloff Wieteke A. Holthuijzen Daniel Simberloff |
| collection | Wiley Open Access |
| contents | Bulk tissue versus amino acid carbon stable isotopes to reveal the diet and basal resource use of an invasive rodent Wieteke A. Holthuijzen Daniel Simberloff Ecosphere Abstract Stable isotope analysis (SIA) is widely used to reconstruct food webs, characterize trophic relationships, and estimate dietary composition. However, bulk tissue SIA (BSIA) can yield imprecise estimates when dietary sources are isotopically similar. We compared carbon SIA of amino acids (δ 13 C‐EAA values) with BSIA (δ 13 C and δ 15 N values) to estimate diet composition and basal resource use of invasive house mice ( Mus musculus ) on Sand Island, part of a remote atoll in the north Pacific Ocean. We aimed to assess whether δ 13 C‐EAA values could improve source differentiation and yield more precise diet estimates and to evaluate whether δ 13 C‐EAA fingerprints could provide insights into the origin and use of basal resources by mice. We applied a Bayesian mixing model using δ 13 C‐EAA values from a subset of 10 mice and associated diet items, with sample selection guided by existing BSIA and next‐generation sequencing datasets. Diet source estimates from the δ 13 C‐EAA model closely resembled those from the BSIA‐based model ( n = 90): arthropods dominated mouse diet, with smaller contributions from seabirds and plants. Estimates from the δ 13 C‐EAA model were more consistent and precise than those from a BSIA model using the same 10 individuals, underscoring the value of informed sample selection. Although use of δ 13 C‐EAA values did not substantially improve separation among isotopically similar sources, it reinforced our previous findings. We also used δ 13 C‐EAA fingerprinting to reconstruct basal resource use. Mice obtained most of their essential amino acids from aquatic basal resources—likely through direct consumption of seabird tissues or indirectly by eating scavenger arthropods—whereas terrestrial resources contributed far less. These findings highlight the ecological impact of mice on Sand Island, showing how they exploit energy and nutrients derived from marine subsidies. Collectively, our results suggest that δ 13 C‐EAA values are most effective when paired with pre‐existing ecological knowledge, especially for omnivores in complex food webs. Applied judiciously, this method may strengthen ecological inferences and provide additional insights into impacts of invasive species—particularly in island ecosystems. 10.1002/ecs2.70549 http://creativecommons.org/licenses/by/4.0/ |
| doi_str_mv | 10.1002/ecs2.70549 |
| format | Artículo Open Access |
| id | wiley_oa_10_1002_ecs2_70549 |
| institution | Wiley Open Access |
| license_str_mv | http://creativecommons.org/licenses/by/4.0/ |
| publishDate | 2026 |
| publisher | Wiley |
| record_format | wiley_oa |
| spellingShingle | Bulk tissue versus amino acid carbon stable isotopes to reveal the diet and basal resource use of an invasive rodent Wieteke A. Holthuijzen Daniel Simberloff Ecosphere Bulk tissue versus amino acid carbon stable isotopes to reveal the diet and basal resource use of an invasive rodent Wieteke A. Holthuijzen Daniel Simberloff Ecosphere Abstract Stable isotope analysis (SIA) is widely used to reconstruct food webs, characterize trophic relationships, and estimate dietary composition. However, bulk tissue SIA (BSIA) can yield imprecise estimates when dietary sources are isotopically similar. We compared carbon SIA of amino acids (δ 13 C‐EAA values) with BSIA (δ 13 C and δ 15 N values) to estimate diet composition and basal resource use of invasive house mice ( Mus musculus ) on Sand Island, part of a remote atoll in the north Pacific Ocean. We aimed to assess whether δ 13 C‐EAA values could improve source differentiation and yield more precise diet estimates and to evaluate whether δ 13 C‐EAA fingerprints could provide insights into the origin and use of basal resources by mice. We applied a Bayesian mixing model using δ 13 C‐EAA values from a subset of 10 mice and associated diet items, with sample selection guided by existing BSIA and next‐generation sequencing datasets. Diet source estimates from the δ 13 C‐EAA model closely resembled those from the BSIA‐based model ( n = 90): arthropods dominated mouse diet, with smaller contributions from seabirds and plants. Estimates from the δ 13 C‐EAA model were more consistent and precise than those from a BSIA model using the same 10 individuals, underscoring the value of informed sample selection. Although use of δ 13 C‐EAA values did not substantially improve separation among isotopically similar sources, it reinforced our previous findings. We also used δ 13 C‐EAA fingerprinting to reconstruct basal resource use. Mice obtained most of their essential amino acids from aquatic basal resources—likely through direct consumption of seabird tissues or indirectly by eating scavenger arthropods—whereas terrestrial resources contributed far less. These findings highlight the ecological impact of mice on Sand Island, showing how they exploit energy and nutrients derived from marine subsidies. Collectively, our results suggest that δ 13 C‐EAA values are most effective when paired with pre‐existing ecological knowledge, especially for omnivores in complex food webs. Applied judiciously, this method may strengthen ecological inferences and provide additional insights into impacts of invasive species—particularly in island ecosystems. 10.1002/ecs2.70549 http://creativecommons.org/licenses/by/4.0/ |
| title | Bulk tissue versus amino acid carbon stable isotopes to reveal the diet and basal resource use of an invasive rodent |
| topic | Ecosphere |
| url | https://esajournals.onlinelibrary.wiley.com/doi/10.1002/ecs2.70549 |