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Husak JF, Lailvaux SP. Stable isotopes reveal sex- and context-dependent amino acid routing in green anole lizards (Anolis carolinensis). J Exp Biol 2024; 227:jeb248024. [PMID: 39155675 DOI: 10.1242/jeb.248024] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2024] [Accepted: 08/07/2024] [Indexed: 08/20/2024]
Abstract
Allocation of acquired resources to phenotypic traits is affected by resource availability and current selective context. While differential investment in traits is well documented, the mechanisms driving investment at lower levels of biological organization, which are not directly related to fitness, remain poorly understood. We supplemented adult male and female Anolis carolinensis lizards with an isotopically labelled essential amino acid (13C-leucine) to track routing in four tissues (muscle, liver, gonads and spleen) under different combinations of resource availability (high- and low-calorie diets) and exercise training (sprint training and endurance capacity). We predicted sprint training should drive routing to muscle, and endurance training to liver and spleen, and that investment in gonads should be of lower priority in each of the cases of energetic stress. We found complex interactions between training regime, diet and tissue type in females, and between tissue type and training, and tissue type and diet in males, suggesting that males and females adjust their 13C-leucine routing strategies differently in response to similar environmental challenges. Importantly, our data show evidence of increased 13C-leucine routing in training contexts not to muscle as we expected, but to the spleen, which turns over blood cells, and to the liver, which supports metabolism under differing energetic scenarios. Our results reveal the context-specific nature of long-term trade-offs associated with increased chronic activity. They also illustrate the importance of considering the costs of locomotion in studies of life-history strategies.
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Affiliation(s)
- Jerry F Husak
- Department of Biology, University of St Thomas, St Paul, MN 55105, USA
| | - Simon P Lailvaux
- Department of Biological Sciences, University of New Orleans, New Orleans, LA 70148, USA
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2
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Durso AM, Kieran TJ, Glenn TC, Mullin SJ. Comparison of Three Methods for Measuring Dietary Composition of Plains Hog-nosed Snakes. HERPETOLOGICA 2022. [DOI: 10.1655/herpetologica-d-21-00023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Affiliation(s)
- Andrew M. Durso
- Department of Biological Sciences, Eastern Illinois University, Charleston, IL 61920, USA
| | - Troy J. Kieran
- Department of Environmental Health Science, University of Georgia, Athens, GA 30602, USA
| | - Travis C. Glenn
- Department of Environmental Health Science, University of Georgia, Athens, GA 30602, USA
| | - Stephen J. Mullin
- Department of Biological Sciences, Eastern Illinois University, Charleston, IL 61920, USA
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3
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Martins LS, Costa-Schmidt LE, Garcia AM, Bastos RF, Rebelato MM, Tozetti AM. The Contribution of Aquatic Plants to the Trophic Ecology of a Sand Dune Lizard in Southern Brazil. SOUTH AMERICAN JOURNAL OF HERPETOLOGY 2021. [DOI: 10.2994/sajh-d-18-00045.1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
Affiliation(s)
- Laís S. Martins
- Instituto de Ciências Biológicas, Universidade Federal do Rio Grande, Avenida Itália, Km 8, CEP 96201-900, Rio Grande, Rio Grande do Sul, Brazil
| | - Luiz E. Costa-Schmidt
- Laboratório de Ecologia de Vertebrados Terrestres. Programa de Pós-Graduação em Biologia, Universidade do Vale do Rio dos Sinos, Avenida Unisinos, 950, CEP 93022-000, São Leopoldo, Rio Grande do Sul, Brazil
| | - Alexandre M. Garcia
- Laboratório de Ictiologia, Instituto de Oceanografia, Universidade Federal do Rio Grande, Avenida Itália, Km 8, Caixa Postal 474, CEP 96203-900, Rio Grande, Rio Grande do Sul, Brazil
| | - Rodrigo F. Bastos
- Laboratório de Nécton, Departamento de Oceanografia, Universidade Federal de Pernambuco, Avenida Arquitetura, s/n, Cidade Universitária, CEP 50740-550, Recife, Pernambuco, Brazil
| | - Marluci M. Rebelato
- Laboratório de Herpetologia, Departamento de Zoologia, Instituto de Biociências, Universidade Federal do Rio Grande do Sul, Avenida Bento Gonçalves, 9500, Agronomia, CEP 91501-970, Porto Alegre, Rio Grande do Sul, Brazil
| | - Alexandro M. Tozetti
- Laboratório de Ecologia de Vertebrados Terrestres. Programa de Pós-Graduação em Biologia, Universidade do Vale do Rio dos Sinos, Avenida Unisinos, 950, CEP 93022-000, São Leopoldo, Rio Grande do Sul, Brazil
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4
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Butterfield TG, Herrel A, Olson ME, Contreras-Garduño J, Macip-Ríos R. Morphology of the limb, shell and head explain the variation in performance and ecology across 14 turtle taxa (12 species). Biol J Linn Soc Lond 2021. [DOI: 10.1093/biolinnean/blab117] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022]
Abstract
Abstract
Given that morphology directly influences the ability of an organism to utilize its habitat and dietary resources, it also influences fitness. Comparing the relationship between morphology, performance and ecology is fundamental to understand how organisms evolve to occupy a wide range of habitats and diets. In turtles, studies have documented important relationships between morphology, performance and ecology, but none was field based or considered limb, shell and head morphology simultaneously. We compared the morphology, performance and ecology of 14 turtle taxa (12 species) in Mexico that range in their affinity to water and in their diet. We took linear measurements of limb, shell and head variables. We measured maximum swimming speed, maximum bite force and how often turtles were encountered on land, and we used stable isotopes to assess trophic position. We used these data to test the following three hypotheses: (1) morphology, performance and ecology covary; (2) limb and shell variables, like hand length, are correlated with swimming speed and the percentage of time spent on land; and (3) head variables, such as head width, are correlated with bite force and stable isotopes. We find support for these hypotheses and provide the first evidence that morphology influences performance and ecology in turtles in the field.
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Affiliation(s)
- Taggert G Butterfield
- Escuela Nacional de Estudios Superiores, Unidad Morelia, Universidad Nacional Autónoma de México, Morelia, Michoacán, México, Mexico
- Posgrado en Ciencias Biológicas, Universidad Nacional Autónoma de México, Unidad de Posgrado, edificio D, Ciudad Universitaria, CDMX, México, Mexico
| | - Anthony Herrel
- UMR 7179 CNRS/MNHN, Département Adaptations du Vivant, 55 rue Buffon, 75005, Paris Cedex 5, France
| | - Mark E Olson
- Posgrado en Ciencias Biológicas, Universidad Nacional Autónoma de México, Unidad de Posgrado, edificio D, Ciudad Universitaria, CDMX, México, Mexico
- Departamento de Botánica, Instituto de Biología, Universidad Nacional Autónoma de México, Ciudad de México (CDMX), Mexico, Mexico
| | - Jorge Contreras-Garduño
- Escuela Nacional de Estudios Superiores, Unidad Morelia, Universidad Nacional Autónoma de México, Morelia, Michoacán, México, Mexico
- Posgrado en Ciencias Biológicas, Universidad Nacional Autónoma de México, Unidad de Posgrado, edificio D, Ciudad Universitaria, CDMX, México, Mexico
| | - Rodrigo Macip-Ríos
- Escuela Nacional de Estudios Superiores, Unidad Morelia, Universidad Nacional Autónoma de México, Morelia, Michoacán, México, Mexico
- Posgrado en Ciencias Biológicas, Universidad Nacional Autónoma de México, Unidad de Posgrado, edificio D, Ciudad Universitaria, CDMX, México, Mexico
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5
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Warne RW, Wolf BO. Nitrogen stable isotope turnover and discrimination in lizards. RAPID COMMUNICATIONS IN MASS SPECTROMETRY : RCM 2021; 35:e9030. [PMID: 33332668 DOI: 10.1002/rcm.9030] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/30/2020] [Revised: 11/16/2020] [Accepted: 12/16/2020] [Indexed: 06/12/2023]
Abstract
RATIONALE Nitrogen stable isotope ratio (δ15 N) processes are not well described in reptiles, which limits reliable inference of trophic and nutrient dynamics. In this study we detailed δ15 N turnover and discrimination (Δ15 N) in diverse tissues of two lizard species, and compared these results with previously published carbon data (δ13 C) to inform estimates of reptilian foraging ecology and nutrient physiology. METHODS We quantified 15 N incorporation and discrimination dynamics over 360 days in blood fractions, skin, muscle, and liver of Sceloporus undulatus and Crotaphytus collaris that differed in body mass. Tissue samples were analyzed on a continuous flow isotope ratio mass spectrometer. RESULTS Δ15 N for plasma and red blood cells (RBCs) ranged between +2.7 and +3.5‰; however, skin, muscle, and liver did not equilibrate, hindering estimates for these somatic tissues. 15 N turnover in plasma and RBCs ranged from 20.7 ± 4 to 303 ± 166 days among both species. Comparison with previously published δ13 C results for these same samples showed that 15 N and 13 C incorporation patterns were uncoupled, especially during winter when hibernation physiology could have played a role. CONCLUSIONS Our results provide estimates of 15 N turnover rates and discrimination values that are essential to using and interpreting isotopes in studies of diet reconstruction, nutrient allocation, and trophic characterization in reptiles. These results also suggest that somatic tissues can be unreliable, while life history shifts in nutrient routing and metabolism potentially cause 15 N and 13 C dynamics to be decoupled.
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Affiliation(s)
- Robin W Warne
- School of Biological Sciences, Southern Illinois University, Carbondale, IL, 62901, USA
| | - Blair O Wolf
- Department of Biology, University of New Mexico, Albuquerque, NM, USA
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6
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Butterfield T, Olson M, Beck D, Macip-Ríos R. Morphology, Performance, and Ecology of Three Sympatric Turtles in a Tropical Dry Forest. COPEIA 2020. [DOI: 10.1643/ce-18-165] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Affiliation(s)
- Taggert Butterfield
- Posgrado en Ciencias Biológicas, Unidad de Posgrado, Universidad Nacional Autónoma de México, Ciudad Universitaria, Coyoacán, CDMX, 04510, Mexico; (TB) . Send reprint requests to TB
| | - Mark Olson
- Posgrado en Ciencias Biológicas, Unidad de Posgrado, Universidad Nacional Autónoma de México, Ciudad Universitaria, Coyoacán, CDMX, 04510, Mexico; (TB) . Send reprint requests to TB
| | - Daniel Beck
- Department of Biological Sciences, Central Washington University, 400 E University Way, Ellensburg, Washington 98926
| | - Rodrigo Macip-Ríos
- Posgrado en Ciencias Biológicas, Unidad de Posgrado, Universidad Nacional Autónoma de México, Ciudad Universitaria, Coyoacán, CDMX, 04510, Mexico; (TB) . Send reprint requests to TB
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7
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McCue MD, Javal M, Clusella‐Trullas S, Le Roux JJ, Jackson MC, Ellis AG, Richardson DM, Valentine AJ, Terblanche JS. Using stable isotope analysis to answer fundamental questions in invasion ecology: Progress and prospects. Methods Ecol Evol 2019. [DOI: 10.1111/2041-210x.13327] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Affiliation(s)
- Marshall D. McCue
- Sable Systems International Las Vegas NV USA
- Department of Conservation Ecology and Entomology Centre for Invasion Biology Stellenbosch University Stellenbosch South Africa
| | - Marion Javal
- Department of Conservation Ecology and Entomology Centre for Invasion Biology Stellenbosch University Stellenbosch South Africa
| | - Susana Clusella‐Trullas
- Centre for Invasion Biology Department of Botany and Zoology Stellenbosch University Stellenbosch South Africa
| | - Johannes J. Le Roux
- Centre for Invasion Biology Department of Botany and Zoology Stellenbosch University Stellenbosch South Africa
- Department of Biological Sciences Macquarie University NSW Australia
| | - Michelle C. Jackson
- Centre for Invasion Biology Department of Botany and Zoology Stellenbosch University Stellenbosch South Africa
- Department of Life Sciences Imperial College London Ascot UK
- Department of Zoology Oxford University Oxford UK
| | - Allan G. Ellis
- Department of Botany and Zoology Stellenbosch University Stellenbosch South Africa
| | - David M. Richardson
- Centre for Invasion Biology Department of Botany and Zoology Stellenbosch University Stellenbosch South Africa
| | - Alex J. Valentine
- Department of Botany and Zoology Stellenbosch University Stellenbosch South Africa
| | - John S. Terblanche
- Department of Conservation Ecology and Entomology Centre for Invasion Biology Stellenbosch University Stellenbosch South Africa
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8
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The Importance of Isotopic Turnover for Understanding Key Aspects of Animal Ecology and Nutrition. DIVERSITY-BASEL 2019. [DOI: 10.3390/d11050084] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
Stable isotope-based methods have proved to be immensely valuable for ecological studies ranging in focus from animal movements to species interactions and community structure. Nevertheless, the use of these methods is dependent on assumptions about the incorporation and turnover of isotopes within animal tissues, which are oftentimes not explicitly acknowledged and vetted. Thus, the purpose of this review is to provide an overview of the estimation of stable isotope turnover rates in animals, and to highlight the importance of these estimates for ecological studies in terrestrial, freshwater, and marine systems that may use a wide range of stable isotopes. Specifically, we discuss 1) the factors that contribute to variation in turnover among individuals and across species, which influences the use of stable isotopes for diet reconstructions, 2) the differences in turnover among tissues that underlie so-called ‘isotopic clocks’, which are used to estimate the timing of dietary shifts, and 3) the use of turnover rates to estimate nutritional requirements and reconstruct histories of nutritional stress from tissue isotope signatures. As we discuss these topics, we highlight recent works that have effectively used estimates of turnover to design and execute informative ecological studies. Our concluding remarks suggest several steps that will improve our understanding of isotopic turnover and support its integration into a wider range of ecological studies.
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9
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Cloyed CS, Eason PK, Dell AI. The thermal dependence of carbon stable isotope incorporation and trophic discrimination in the domestic cricket, Acheta domesticus. JOURNAL OF INSECT PHYSIOLOGY 2018; 107:34-40. [PMID: 29432766 DOI: 10.1016/j.jinsphys.2018.02.003] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/08/2017] [Revised: 01/12/2018] [Accepted: 02/08/2018] [Indexed: 06/08/2023]
Abstract
Stable isotopes are valuable tools in physiological and ecological research, as they can be used to estimate diet, habitat use, and resource allocation. However, in most cases a priori knowledge of two key properties of stable isotopes is required, namely their rate of incorporation into the body (incorporation rate) and the change of isotope values between consumers and resources that arises during incorporation of the isotopes into the consumer's tissues (trophic discrimination). Previous studies have quantified these properties across species and tissue types, but little is known about how they vary with temperature, a key driver of many biological rates and times. Here, we explored for the first time how temperature affects both carbon incorporation rate and trophic discrimination via growth rates, using the domestic cricket, Acheta domesticus. We raised crickets at 16 °C, 21 °C, and 26 °C and showed that temperature increased carbon isotope incorporation rate, which was driven by both an increased growth rate and catabolism at higher temperatures. Trophic discrimination of carbon isotopes decreased at higher temperatures, which we attributed to either lower activation energies needed to synthesize non-essential amino acids at higher temperatures or the increased utilization of available resources of consumers at higher temperatures. Our results demonstrate that temperature is a key driver of both carbon isotope incorporation rate and trophic discrimination, via mechanisms that likely persist across all ectotherms. Experiments to determine incorporation rates and trophic discrimination factors in ectotherms must include temperature as a major factor, and natural variation in temperature might have significant effects on these isotopic properties that then can affect inferences made from isotope values.
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Affiliation(s)
- Carl S Cloyed
- National Great Rivers Research and Education Center, East Alton, IL 62024, United States; Washington University in St. Louis, Department of Biology, St. Louis, MO 63130, United States.
| | - Perri K Eason
- University of Louisville, Department of Biology, Louisville, KY 40292, United States
| | - Anthony I Dell
- National Great Rivers Research and Education Center, East Alton, IL 62024, United States; Washington University in St. Louis, Department of Biology, St. Louis, MO 63130, United States
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10
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Carter WA, Cooper-Mullin C, McWilliams SR. Turnover of muscle lipids and response to exercise differ between neutral and polar fractions in a model songbird, the zebra finch. ACTA ACUST UNITED AC 2018; 221:jeb.168823. [PMID: 29444847 DOI: 10.1242/jeb.168823] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2017] [Accepted: 02/01/2018] [Indexed: 01/12/2023]
Abstract
The turnover rates of tissues and their constituent molecules give us insights into animals' physiological demands and their functional flexibility over time. Thus far, most studies of this kind have focused on protein turnover, and few have considered lipid turnover despite an increasing appreciation of the functional diversity of this class of molecules. We measured the turnover rates of neutral and polar lipids from the pectoralis muscles of a model songbird, the zebra finch (Taeniopygia guttata, N=65), in a 256 day C3/C4 diet shift experiment, with tissue samples taken at 10 time points. We also manipulated the physiological state of a subset of these birds with a 10 week flight training regimen to test the effect of exercise on lipid turnover. We measured lipid δ13C values via isotope ratio mass spectrometry (IRMS) and estimated turnover in different fractions and treatment groups with non-linear mixed-effect regression. We found a significant difference between the mean retention times (τ) of neutral and polar lipids (t119=-2.22, P=0.028), with polar lipids (τ=11.80±1.28 days) having shorter retention times than neutral lipids (τ=19.47±3.22 days). When all birds were considered, we also found a significant decrease in the mean retention time of polar lipids in exercised birds relative to control birds (difference=-2.2±1.83 days, t56=-2.37, P=0.021), but not neutral lipids (difference=4.2± 7.41 days, t56=0.57, P=0.57). A larger, more variable neutral lipid pool and the exposure of polar lipids in mitochondrial membranes to oxidative damage and increased turnover provide mechanisms consistent with our results.
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Affiliation(s)
- Wales A Carter
- Department of Natural Resources Science, University of Rhode Island, Kingston, RI 02881, USA
| | - Clara Cooper-Mullin
- Department of Natural Resources Science, University of Rhode Island, Kingston, RI 02881, USA
| | - Scott R McWilliams
- Department of Natural Resources Science, University of Rhode Island, Kingston, RI 02881, USA
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11
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Hofmeyr MD, Henen BT, Walton S. Season, sex and age variation in the haematology and body condition of geometric tortoises Psammobates geometricus. AFRICAN ZOOLOGY 2017. [DOI: 10.1080/15627020.2017.1284575] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
Affiliation(s)
- Margaretha D Hofmeyr
- Chelonian Biodiversity and Conservation – Southern Africa, Biodiversity and Conservation Biology Department, University of the Western Cape, Bellville, South Africa
| | - Brian T Henen
- Chelonian Biodiversity and Conservation – Southern Africa, Biodiversity and Conservation Biology Department, University of the Western Cape, Bellville, South Africa
- Current address: Marine Air Ground Task Force Training Command, Natural Resources and Environmental Affairs, Marine Corps Air Ground Combat Center, Twentynine Palms, California, USA
| | - Shasheen Walton
- Chelonian Biodiversity and Conservation – Southern Africa, Biodiversity and Conservation Biology Department, University of the Western Cape, Bellville, South Africa
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12
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deVries MS, del Rio CM, Tunstall TS, Dawson TE. Isotopic incorporation rates and discrimination factors in mantis shrimp crustaceans. PLoS One 2015; 10:e0122334. [PMID: 25835953 PMCID: PMC4383329 DOI: 10.1371/journal.pone.0122334] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2014] [Accepted: 02/10/2015] [Indexed: 11/19/2022] Open
Abstract
Stable isotope analysis has provided insights into the trophic ecology of a wide diversity of animals. Knowledge about isotopic incorporation rates and isotopic discrimination between the consumer and its diet for different tissue types is essential for interpreting stable isotope data, but these parameters remain understudied in many animal taxa and particularly in aquatic invertebrates. We performed a 292-day diet shift experiment on 92 individuals of the predatory mantis shrimp, Neogonodactylus bredini, to quantify carbon and nitrogen incorporation rates and isotope discrimination factors in muscle and hemolymph tissues. Average isotopic discrimination factors between mantis shrimp muscle and the new diet were 3.0 ± 0.6 ‰ and 0.9 ± 0.3 ‰ for carbon and nitrogen, respectively, which is contrary to what is seen in many other animals (e.g. C and N discrimination is generally 0–1 ‰ and 3–4 ‰, respectively). Surprisingly, the average residence time of nitrogen in hemolymph (28.9 ± 8.3 days) was over 8 times longer than that of carbon (3.4 ± 1.4 days). In muscle, the average residence times of carbon and nitrogen were of the same magnitude (89.3 ± 44.4 and 72.8 ± 18.8 days, respectively). We compared the mantis shrimps’ incorporation rates, along with rates from four other invertebrate taxa from the literature, to those predicted by an allometric equation relating carbon incorporation rate to body mass that was developed for teleost fishes and sharks. The rate of carbon incorporation into muscle was consistent with rates predicted by this equation. Our findings provide new insight into isotopic discrimination factors and incorporation rates in invertebrates with the former showing a different trend than what is commonly observed in other animals.
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Affiliation(s)
- Maya S. deVries
- Department of Integrative Biology, University of California, Berkeley, California, United States of America
- * E-mail:
| | - Carlos Martínez del Rio
- Department of Zoology and Physiology, University of Wyoming, Laramie, Wyoming, United States of America
| | - Tate S. Tunstall
- Department of Integrative Biology, University of California, Berkeley, California, United States of America
| | - Todd E. Dawson
- Department of Integrative Biology, University of California, Berkeley, California, United States of America
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13
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Isotopic Discrimination Factors (Δ13C and Δ15N) between Tissues and Diet of the Broad-Snouted Caiman (Caiman latirostris). J HERPETOL 2014. [DOI: 10.1670/12-274] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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14
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Murray IW, Wolf BO. Desert tortoise (Gopherus agassizii) dietary specialization decreases across a precipitation gradient. PLoS One 2013; 8:e66505. [PMID: 23840495 PMCID: PMC3696026 DOI: 10.1371/journal.pone.0066505] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2013] [Accepted: 05/07/2013] [Indexed: 11/28/2022] Open
Abstract
We studied the plant resource use between and within populations of desert tortoise (Gopherus agassizii) across a precipitation gradient in the Sonoran Desert of Arizona. The carbon and nitrogen stable isotope values in animal tissues are a reflection of the carbon and nitrogen isotope values in diet, and consequently represent a powerful tool to study animal feeding ecology. We measured the δ13C and δ15N values in the growth rings on the shells of tortoises in different populations to characterize dietary specialization and track tortoise use of isotopically distinct C4/CAM versus C3 plant resources. Plants using C3 photosynthesis are generally more nutritious than C4 plants and these trait differences can have important growth and fitness consequences for consumers. We found that dietary specialization decreases in successively drier and less vegetated sites, and that broader population niche widths are accompanied by an increase in the dietary variability between individuals. Our results highlight how individual consumer plant resource use is bounded under a varying regime of precipitation and plant productivity, lending insight into how intra-individual dietary specialization varies over a spatial scale of environmental variability.
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Affiliation(s)
- Ian W Murray
- Department of Biology, University of New Mexico, Albuquerque, New Mexico, United States of America.
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15
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Caut S. Isotope incorporation in broad-snouted caimans (crocodilians). Biol Open 2013; 2:629-34. [PMID: 23789113 PMCID: PMC3683165 DOI: 10.1242/bio.20134945] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2013] [Accepted: 04/23/2013] [Indexed: 11/22/2022] Open
Abstract
The trophic ecology and migration of vertebrate species have been increasingly studied using stable isotope analysis. However, this approach requires knowledge on how dietary isotopic values are reflected in consumers' tissues. To date, this information has only been obtained for a handful of ectotherms; in particular, little is known about crocodilians. In this study, diet-tissue discrimination factors (DTDFs) and carbon and nitrogen stable isotope turnover rates were estimated for plasma, red blood cells (RBCs), and muscle obtained from broad-snouted caimans (Caiman latirostris). Individuals were fed two different control diets for 189 days. DTDFs for δ15N (Δ15N) and δ13C (Δ13C) ranged from −2.24‰ to 0.39‰ and from −0.52‰ to 1.06‰, respectively. Isotope turnover rates in tissues, expressed as half-lives, ranged from 11 to 71 days, with plasma<muscle<RBCs. Δ15N was found to be particularly small, even when compared to values found for other ectotherms, a result that may be linked to the unique excretion physiology of crocodilians. These stable isotope incorporation data should help inform future interpretations of isotopic values obtained in the field for this taxon.
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Affiliation(s)
- Stephane Caut
- Estación Biológica de Doñana, Consejo Superior de Investigaciones Científicas (CSIC) , Apartado 1056, E-41080 Sevilla , Spain
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16
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Rosenblatt AE, Heithaus MR. Slow Isotope Turnover Rates and Low Discrimination Values in the American Alligator: Implications for Interpretation of Ectotherm Stable Isotope Data. Physiol Biochem Zool 2013; 86:137-48. [DOI: 10.1086/668295] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
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17
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Lara N, Marques T, Montelo K, de Ataídes Á, Verdade L, Malvásio A, de Camargo P. A trophic study of the sympatric Amazonian freshwater turtles Podocnemis unifilis and Podocnemis expansa (Testudines, Podocnemidae) using carbon and nitrogen stable isotope analyses. CAN J ZOOL 2012. [DOI: 10.1139/cjz-2012-0143] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The Yellow-spotted River Turtle ( Podocnemis unifilis Troschel, 1848) and the South American River Turtle (Podocnemis expansa (Schweigger, 1812)) are two turtles species that are widely distributed and have ecological, economic, and cultural importance in the Amazon basin. Although sympatric regarding most of their distribution, few studies have addressed the coexistence of these two species. To examine this, we analyzed the trophic level and the primary carbon source from the diets of both species in Baixo Araguaia, Tocantins, Brazil, using stable isotope analyses of carbon (δ13C) and nitrogen (δ15N). We also verified possible intraspecific variations (related to sex and body mass) in the trophic levels and primary carbon sources of their diets. Podocnemis unifilis had higher values of δ15N than P. expansa, averaging 7.59‰ and 5.06‰, respectively, a difference which may indicate a possible trophic change owing to exploiting different food resources. No differences were found between the two species in relation to δ13C (mean values of –26.2‰ and –26.1‰, respectively). The similarity between δ13C values suggests that the sources of their basal feeding are the same, consisting mainly of C3 plants. There was no intraspecific variation in the values of δ13C and δ15N.
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Affiliation(s)
- N.R.F. Lara
- Laboratory of Isotope Ecology, Center for Nuclear Energy in Agriculture, University of São Paulo, Avenue Centenário, 303, 13416-000, Piracicaba, SP, Brazil
| | - T.S. Marques
- Laboratory of Isotope Ecology, Center for Nuclear Energy in Agriculture, University of São Paulo, Avenue Centenário, 303, 13416-000, Piracicaba, SP, Brazil
| | - K.M. Montelo
- Federal University of Tocantins, ALCNO 14, Avenue NS 15, s/n, Bloco III, sala 15A, CEP-77010-970, Palmas, TO, Brazil
| | - Á.G. de Ataídes
- Federal University of Tocantins, ALCNO 14, Avenue NS 15, s/n, Bloco III, sala 15A, CEP-77010-970, Palmas, TO, Brazil
| | - L.M. Verdade
- Laboratory of Isotope Ecology, Center for Nuclear Energy in Agriculture, University of São Paulo, Avenue Centenário, 303, 13416-000, Piracicaba, SP, Brazil
| | - A. Malvásio
- Federal University of Tocantins, ALCNO 14, Avenue NS 15, s/n, Bloco III, sala 15A, CEP-77010-970, Palmas, TO, Brazil
| | - P.B. de Camargo
- Laboratory of Isotope Ecology, Center for Nuclear Energy in Agriculture, University of São Paulo, Avenue Centenário, 303, 13416-000, Piracicaba, SP, Brazil
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