Meta‐analysis of primary producer amino acid δ<sup>15</sup>N values and their influence on trophic position estimation

Ramirez, Matthew D.; Besser, Alexi C.; Newsome, Seth D.; McMahon, Kelton W.

doi:10.1111/2041-210x.13678

Cited by 50 publications

(59 citation statements)

References 140 publications

(223 reference statements)

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“…Based on the consistency in trophic AA and source AA δ 15 N, an AA‐based TP (TP AA ) equation was developed from a bulk SIR‐based TP equation, as shown in Figure 5a (Chikaraishi et al, 2009 ). The TP AA is a transformative approach of trophic AA δ 15 N for consumer that is internally indexed to baseline component (or nutritional resource) with source AA δ 15 N variable (Kjeldgaard et al, 2021 ; McMahon & McCarthy, 2016 ; Ohkouchi et al, 2017 ; Ramirez et al, 2021 ). It is applicable for whole bodies (or any proteinaceous tissue types) from environmental samples to zooplankton and higher trophic‐level fish and apex predators (Cherel et al, 2019 ; Choi & Shin, 2021 ; Choi et al, 2020 ; Germain et al, 2013 ; Laiz‐Carrión et al, 2019 ; Mompean et al, 2016 ; Richards et al, 2020 ).…”

Section: Common Use Of Aa δ 15 N and Aa δ ...mentioning

confidence: 99%

Amino acid nitrogen and carbon isotope data: Potential and implications for ecological studies

Yun

Larsen

Choi

et al. 2022

Ecology and Evolution

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Explaining food web dynamics, stability, and functioning depend substantially on understanding of feeding relations within a community. Bulk stable isotope ratios (SIRs) in natural abundance are well‐established tools to express direct and indirect feeding relations as continuous variables across time and space. Along with bulk SIRs, the SIRs of individual amino acids (AAs) are now emerging as a promising and complementary method to characterize the flow and transformation of resources across a diversity of organisms, from microbial domains to macroscopic consumers. This significant AA‐SIR capacity is based on empirical evidence that a consumer's SIR, specific to an individual AA, reflects its diet SIR coupled with a certain degree of isotopic differences between the consumer and its diet. However, many empirical ecologists are still unfamiliar with the scope of applicability and the interpretative power of AA‐SIR. To fill these knowledge gaps, we here describe a comprehensive approach to both carbon and nitrogen AA‐SIR assessment focusing on two key topics: pattern in AA‐isotope composition across spatial and temporal scales, and a certain variability of AA‐specific isotope differences between the diet and the consumer. On this basis we review the versatile applicability of AA‐SIR to improve our understanding of physiological processes as well as food web functioning, allowing us to reconstruct dominant basal dietary sources and trace their trophic transfers at the specimen and community levels. Given the insightful and opportunities of AA‐SIR, we suggest future applications for the dual use of carbon and nitrogen AA‐SIR to study more realistic food web structures and robust consumer niches, which are often very difficult to explain in nature.

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Section: Common Use Of Aa δ 15 N and Aa δ ...mentioning

confidence: 99%

Amino acid nitrogen and carbon isotope data: Potential and implications for ecological studies

Yun

Larsen

Choi

et al. 2022

Ecology and Evolution

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“…The offset between δ 15 N Glx and δ 15 N Phe values (i.e., β value) is significantly different in plants performing C 3 (~ − 8.4‰) versus C 4 (~ 0.4‰) photosynthesis 20 , although substantial variation also exists among C 3 plants (e.g., ranging from − 2.6‰ in Urtica doica to − 12.2‰ in Sambucus nigra) depending on the degree of vascularization 28 and amount of lignin produced by the plant species 27 . Mammalian herbivores, whether feeding on C 3 or C 4 resources, however, do not differ significantly in ∆δ 15 N Glx − δ 15 N Phe values (p-value = 0.77, SI Dataset).…”

Section: Discussionmentioning

confidence: 98%

“…Indeed, the equation relies on the assumption that the β value (isotopic differences between glutamate and phenylalanine ["big delta" Δ] in primary producers) and the TDF ( 15 N-enrichment of glutamate relative to phenylalanine per trophic level change [Δ Glx − Δ Phe ]) are both constant across all organisms within an ecosystem. For terrestrial ecosystems, β values of − 8.4‰ and − 0.4‰ are considered representative of C 3 and C 4 plant-dominated ecosystems, respectively 20,27 ; however, a recent meta-analysis of β values, demonstrated considerably more variation than currently acknowledged 28 . On the other hand, a standard TDF value of 7.6‰ has been used to calculate trophic positions of all consumers, whether terrestrial or aquatic, modern or extinct, vertebrate or invertebrate, yet its assumption of constancy has only been tested on marine invertebrates, fishes, birds, insects, and heterotrophic bacteria, where it is also known to vary 16,20,[29][30][31] .…”

mentioning

confidence: 99%

Isotope data from amino acids indicate Darwin’s ground sloth was not an herbivore

Tejada

Flynn

MacPhee

et al. 2021

Sci Rep

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Fossil sloths are regarded as obligate herbivores for reasons including peculiarities of their craniodental morphology and that all living sloths feed exclusively on plants. We challenge this view based on isotopic analyses of nitrogen of specific amino acids, which show that Darwin’s ground sloth Mylodon darwinii was an opportunistic omnivore. This direct evidence of omnivory in an ancient sloth requires reevaluation of the ecological structure of South American Cenozoic mammalian communities, as sloths represented a major component of these ecosystems across the past 34 Myr. Furthermore, by analyzing modern mammals with known diets, we provide a basis for reliable interpretation of nitrogen isotopes of amino acids of fossils. We argue that a widely used equation to determine trophic position is unnecessary, and that the relative isotopic values of the amino acids glutamate and phenylalanine alone permit reliable reconstructions of trophic positions of extant and extinct mammals.

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“…toward improving trophic position assessments via CSIA-AA (e.g., Ohkouchi et al, 2017;Ishikawa, 2018;Ramirez et al, 2021).…”

Section: Challenges In the Determination Of Trophic Positionsmentioning

confidence: 99%

Toward a Solution of the “Peruvian Puzzle”: Pelagic Food-Web Structure and Trophic Interactions in the Northern Humboldt Current Upwelling System Off Peru

et al. 2022

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The northern Humboldt Current upwelling system (HCS) belongs to the most productive marine ecosystems, providing five to eight times higher fisheries landings per unit area than other coastal upwelling systems. To solve this “Peruvian puzzle”, to elucidate the pelagic food-web structure and to better understand trophic interactions in the HCS, a combined stable isotope and fatty acid trophic biomarker approach was adopted for key zooplankton taxa and higher trophic positions with an extensive spatial coverage from 8.5 to 16°S and a vertical range down to 1,000 m depth. A pronounced regional shift by up to ∼5‰ in the δ15N baseline of the food web occurred from North to South. Besides regional shifts, δ15N ratios of particulate organic matter (POM) also tended to increase with depth, with differences of up to 3.8‰ between surface waters and the oxygen minimum zone. In consequence, suspension-feeding zooplankton permanently residing at depth had up to ∼6‰ higher δ15N signals than surface-living species or diel vertical migrants. The comprehensive data set covered over 20 zooplankton taxa and indicated that three crustacean species usually are key in the zooplankton community, i.e., the copepods Calanus chilensis at the surface and Eucalanus inermis in the pronounced OMZ and the krill Euphausia mucronata, resulting in an overall low number of major trophic pathways toward anchovies. In addition, the semi-pelagic squat lobster Pleuroncodes monodon appears to play a key role in the benthic-pelagic coupling, as indicated by highest δ13C’ ratios of −14.7‰. If feeding on benthic resources and by diel vertical migration, they provide a unique pathway for returning carbon and energy from the seafloor to the epipelagic layer, increasing the food supply for pelagic fish. Overall, these mechanisms result in a very efficient food chain, channeling energy toward higher trophic positions and partially explaining the “Peruvian puzzle” of enormous fish production in the HCS.

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Meta‐analysis of primary producer amino acid δ¹⁵N values and their influence on trophic position estimation

Cited by 50 publications

References 140 publications

Amino acid nitrogen and carbon isotope data: Potential and implications for ecological studies

Amino acid nitrogen and carbon isotope data: Potential and implications for ecological studies

Isotope data from amino acids indicate Darwin’s ground sloth was not an herbivore

Toward a Solution of the “Peruvian Puzzle”: Pelagic Food-Web Structure and Trophic Interactions in the Northern Humboldt Current Upwelling System Off Peru

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Meta‐analysis of primary producer amino acid δ15N values and their influence on trophic position estimation

Cited by 50 publications

References 140 publications

Amino acid nitrogen and carbon isotope data: Potential and implications for ecological studies

Amino acid nitrogen and carbon isotope data: Potential and implications for ecological studies

Isotope data from amino acids indicate Darwin’s ground sloth was not an herbivore

Toward a Solution of the “Peruvian Puzzle”: Pelagic Food-Web Structure and Trophic Interactions in the Northern Humboldt Current Upwelling System Off Peru

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Meta‐analysis of primary producer amino acid δ¹⁵N values and their influence on trophic position estimation