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Olsen AY, Smith A, Hempstead C, Larson SE. Analytical Validation and Assessment of Baseline Fecal Glucocorticoid Metabolites in Northern Sea Otters ( Enhydra lutris kenyoni) in Human Care. Animals (Basel) 2023; 13:2175. [PMID: 37443973 DOI: 10.3390/ani13132175] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2023] [Revised: 06/30/2023] [Accepted: 06/30/2023] [Indexed: 07/15/2023] Open
Abstract
Fecal glucocorticoid metabolites (FGMs) have been used as a non-invasive and indirect measurement of the complex stress response in a variety of species. Animals in facilities under managed care allow for the longitudinal study of FGMs in a controlled environment. Animal histories often include environmental, husbandry, and medical notes that can be matched to FGM concentrations to aid in the physiological validation of adrenal stimulation and response. The goal of this study was to demonstrate analytical validations using two enzyme-linked immunosorbent assays (EIA) to measure FGMs from northern sea otters (Enhydra lutris kenyoni) under human care (Seattle Aquarium, Seattle, WA, USA) and to determine baseline and stress response spike levels for individual sea otters. Individual variation was found among the four subjects in the study with fecal baseline levels ranging from 20.2 to 83.7 ng/g for cortisol-immunoreactive metabolites and 52.3 to 102 ng/g for corticosterone-immunoreactive metabolites. As a retrospective study, 39 percent of hormone peaks were associated with notes and most FGM spikes were associated with veterinary procedures or days in which enrichment items were provided and produced an excitatory response. Monitoring baseline FGMs levels and events associated with hormone peak values may provide insight into effective husbandry management to improve the overall welfare of sea otters and other marine mammals.
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Affiliation(s)
- Amy Y Olsen
- Seattle Aquarium, 1483 Alaskan Way, Seattle, WA 98101, USA
| | - Angela Smith
- Seattle Aquarium, 1483 Alaskan Way, Seattle, WA 98101, USA
| | | | - Shawn E Larson
- Seattle Aquarium, 1483 Alaskan Way, Seattle, WA 98101, USA
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Font-Porterias N, McNelis MG, Comas D, Hlusko LJ. Evidence of selection in the ectodysplasin pathway among endangered aquatic mammals. Integr Org Biol 2022; 4:obac018. [PMID: 35874492 PMCID: PMC9299678 DOI: 10.1093/iob/obac018] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2022] [Revised: 05/06/2022] [Accepted: 05/21/2022] [Indexed: 11/13/2022] Open
Abstract
Synopsis The ectodysplasin pathway has been a target of evolution repeatedly. Genetic variation in the key genes of this pathway (EDA, EDAR, and EDARADD) results in a rich source of pleiotropic effects across ectodermally-derived structures, including teeth, hair, sweat glands, and mammary glands. In addition, a non-canonical Wnt pathway has a very similar functional role, making variation in the WNT10A gene also of evolutionary significance. The adaptation of mammals to aquatic environments has occurred independently in at least 4 orders, whose species occupy a wide geographic range (from equatorial to polar regions) and exhibit great phenotypic variation in ectodermally-derived structures, including the presence or absence of fur and extreme lactational strategies. The role of the ectodysplasin pathway in the adaptation to aquatic environments has been never explored in mammalian species. In the present study, we analyze the genetic variation in orthologous coding sequences from EDA, EDAR, EDARADD, and WNT10A genes together with ectodermally-derived phenotypic variation from 34 aquatic and non-aquatic mammalian species to assess signals of positive selection, gene-trait coevolution, and genetic convergence. Our study reveals strong evidence of positive selection in a proportion of coding sites in EDA and EDAR genes in 3 endangered aquatic mammals (the Hawaiian monk seal, the Yangtze finless porpoise, and the sea otter). We hypothesize functional implications potentially related to the adaptation to the low-latitude aquatic environment in the Hawaiian monk seal and the freshwater in the Yangtze finless porpoise. The signal in the sea otter is likely the result of an increased genetic drift after an intense bottleneck and reduction of genetic diversity. Besides positive selection, we have not detected robust signals of gene-trait coevolution or convergent amino acid shifts in the ectodysplasin pathway associated with shared phenotypic traits among aquatic mammals. This study provides new evidence of the evolutionary role of the ectodysplasin pathway and encourages further investigation, including functional studies, to fully resolve its relationship with mammalian aquatic adaptation. Spanish La vía de la ectodisplasina ha sido objeto de la evolución repetidamente. La variación genética en los principales genes de esta vía (EDA, EDAR y EDARADD) da como resultado una gran diversidad de efectos pleiotrópicos en las estructuras derivadas del ectodermo, incluidos los dientes, el cabello, las glándulas sudoríparas y las glándulas mamarias. Además, una vía wnt no canónica tiene un papel funcional muy similar, por lo que la variación en el gen WNT10A también tiene importancia evolutiva. La adaptación de los mamíferos a los entornes acuáticos se ha producido de forma independiente en al menos cuatro órdenes, cuyas especies ocupan un amplio rango geográfico (desde regiones ecuatoriales a polares) y presentan una gran variación fenotípica en las estructuras derivadas del ectodermo, incluyendo la presencia o ausencia de pelaje y estrategias de lactancia muy diferentes. El papel de la vía de la ectodisplasina en la adaptación a entornos acuáticos no se ha explorado nunca en especies de mamíferos. En este estudio, analizamos la variación genética en las secuencias codificantes ortólogas de los genes EDA, EDAR, EDARADD y WNT10A junto con la variación fenotípica derivada del ectodermo de 34 especies de mamíferos acuáticos y no acuáticos para evaluar señales de selección positiva, coevolución gen-rasgo y convergencia genética. Nuestro estudio revela señales de selección positiva en regiones de las secuencias codificantes de los genes EDA y EDAR en tres mamíferos acuáticos en peligro de extinción (la foca monje de Hawái, la marsopa lisa y la nutria marina). Estas señales podrían tener implicaciones funcionales potencialmente relacionadas con la adaptación al entorno acuático de baja latitud en la foca monje de Hawái y el agua dulce en la marsopa lisa. La señal en la nutria marina es probablemente el resultado de una mayor deriva genética tras un intenso un cuello de botella y una reducción de la diversidad genética. A parte de selección positiva, no hemos detectado señales sólidas de coevolución gen-rasgo o cambios convergentes de aminoácidos en la vía de la ectodisplasina asociados a rasgos fenotípicos compartidos entre mamíferos acuáticos. Este estudio proporciona nuevas evidencias del papel evolutivo de la vía de la ectodisplasina y quiere promover futuras investigaciones con estudios funcionales para acabar de resolver la relación de esta vía con la adaptación acuática de los mamíferos.
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Affiliation(s)
- Neus Font-Porterias
- Departament de Ciències Experimentals i de la Salut, Universitat Pompeu Fabra, Institut de Biologia Evolutiva (UPF-CSIC) , Barcelona , Spain
| | - Madeline G McNelis
- Department of Integrative Biology, University of California Berkeley , California , USA
| | - David Comas
- Departament de Ciències Experimentals i de la Salut, Universitat Pompeu Fabra, Institut de Biologia Evolutiva (UPF-CSIC) , Barcelona , Spain
| | - Leslea J Hlusko
- Department of Integrative Biology, University of California Berkeley , California , USA
- National Research Center on Human Evolution (CENIEH) , Burgos , Spain
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Wilson AE, Michaud SA, Jackson AM, Stenhouse G, McClelland CJR, Coops NC, Janz DM. Protein biomarkers in serum as a conservation tool to assess reproduction: a case study on brown bears ( Ursus arctos). CONSERVATION PHYSIOLOGY 2021; 9:coab091. [PMID: 34888057 PMCID: PMC8651255 DOI: 10.1093/conphys/coab091] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 08/20/2021] [Revised: 10/26/2021] [Accepted: 11/01/2021] [Indexed: 06/13/2023]
Abstract
Monitoring the reproductive characteristics of a species can complement existing conservation strategies by understanding the mechanisms underlying demography. However, methodology to determine important aspects of female reproductive biology is often absent in monitoring programs for large mammals. Protein biomarkers may be a useful tool to detect physiological changes that are indicative of reproductive state. This study aimed to identify protein biomarkers of reproductive status in serum collected from free-ranging female brown bears (Ursus arctos) in Alberta, Canada, from 2001 to 2018. We hypothesized that the expression of proteins related to reproduction in addition to energetics and stress can be used to answer specific management-focused questions: (i) identify when a female is pregnant, (ii) detect if a female is lactating, (iii) determine age of sexual maturity (i.e. primiparity) and (iv) assess female fertility (i.e. reproduction rate). Furthermore, we investigated if silver spoon effects (favourable early life conditions provide fitness benefits through adulthood) could be determined using protein expression. A target panel of 19 proteins with established relationships to physiological function was measured by peptide-based analysis using liquid chromatography and multiple reaction monitoring mass spectrometry and their differential expression was evaluated using a Wilcoxon signed-rank test. We found biomarkers of pregnancy (apolipoprotein B-100 and afamin), lactation (apolipoprotein B-100 and alpha-2-macroglobulin) and sexual maturity (corticosteroid-binding globulin), but there were no statistically significant relationships with protein expression and fertility. The expression of proteins related to reproduction (afamin) and energetics (vitamin-D binding protein) was associated with the nutritional quality of the individual's present habitat rather than their early life habitat. This study highlights potential biomarkers of reproductive status and provides additional methods for monitoring physiological function in wildlife to inform conservation.
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Affiliation(s)
- Abbey E Wilson
- Department of Veterinary Biomedical Sciences, University of Saskatchewan, 52 Campus Drive, Saskatoon, Saskatchewan S7N 5B4, Canada
| | - Sarah A Michaud
- The University of Victoria Genome BC Proteomics Centre, 4464 Markham St #3101, Victoria, British Columbia V8Z 7X8, Canada
| | - Angela M Jackson
- The University of Victoria Genome BC Proteomics Centre, 4464 Markham St #3101, Victoria, British Columbia V8Z 7X8, Canada
| | - Gordon Stenhouse
- Grizzly Bear Program, fRI Research, 1176 Switzer Drive, Hinton, Alberta T7V 1V3, Canada
| | | | - Nicholas C Coops
- Department of Forest Resource Management, University of British Columbia, 2424 Main Mall, Vancouver, British Columbia V6T 1Z4, Canada
| | - David M Janz
- Department of Veterinary Biomedical Sciences, University of Saskatchewan, 52 Campus Drive, Saskatoon, Saskatchewan S7N 5B4, Canada
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Keestra S, Högqvist Tabor V, Alvergne A. Reinterpreting patterns of variation in human thyroid function: An evolutionary ecology perspective. EVOLUTION MEDICINE AND PUBLIC HEALTH 2021; 9:93-112. [PMID: 34557302 PMCID: PMC8454515 DOI: 10.1093/emph/eoaa043] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/29/2020] [Accepted: 11/02/2020] [Indexed: 12/21/2022]
Abstract
Thyroid hormone reference intervals—used to determine normal thyroid
function —currently don’t take into account many significant
factors that can cause variation in thyroid hormone levels. These factors
include age, sex, ethnicity, season, time of day, iodine content in the diet,
socioeconomic status, stress levels, body composition, immune status, menstrual
cycle phase, and overall health status. This paper shows how early life
experiences as well as short term stressors may affect variation in thyroid
function. These are energetic challenges to which the thyroid physiology can
respond to. Our investigation shows that much variation in thyroid function is
natural. It may result from a complex interplay of evolutionary, genetic,
developmental, and physiological factors in response to energetic challenges in
the environment, beyond what is currently considered in biomedicine. A new
research agenda for thyroid health should explore the way that diversity in
thyroid function has evolved as a response to different contexts people live
in—like focusing on how people’s metabolisms adapt to the
energetic requirements of their environments. Two hundred million people worldwide experience some form of thyroid disorder,
with women being especially at risk. However, why human thyroid function varies
between populations, individuals, and across the lifespan has attracted little
research to date. This limits our ability to evaluate the conditions under which
patterns of variation in thyroid function are best understood as
‘normal’ or ‘pathological’. In this review, we
aim to spark interest in research aimed at understanding the causes of variation
in thyroid phenotypes. We start by assessing the biomedical literature on
thyroid imbalance to discuss the validity of existing reference intervals for
diagnosis and treatment across individuals and populations. We then propose an
evolutionary ecological framework for understanding the phylogenetic, genetic,
ecological, developmental, and physiological causes of normal variation in
thyroid function. We build on this approach to suggest testable predictions for
how environmental challenges interact with individual circumstances to influence
the onset of thyroid disorders. We propose that dietary changes, ecological
disruptions of co-evolutionary processes during pregnancy and with pathogens,
emerging infections, and exacerbated stress responses can contribute to
explaining the onset of thyroid diseases. For patients to receive the best
personalized care, research into the causes of thyroid variation at multiple
levels is needed.
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Affiliation(s)
- Sarai Keestra
- School of Anthropology & Museum Ethnography, University of Oxford, Oxford, UK.,Amsterdam UMC, University of Amsterdam, Amsterdam, The Netherlands
| | | | - Alexandra Alvergne
- School of Anthropology & Museum Ethnography, University of Oxford, Oxford, UK.,ISEM, Université de Montpellier, CNRS, IRD, EPHE, Montpellier, France
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Zhou W, Gao K, Ma Y, Wang L, Wang M, Wei F, Nie Y. Seasonal dynamics of parasitism and stress physiology in wild giant pandas. CONSERVATION PHYSIOLOGY 2020; 8:coaa085. [PMID: 33014375 PMCID: PMC7521442 DOI: 10.1093/conphys/coaa085] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 03/20/2020] [Revised: 06/19/2020] [Accepted: 08/20/2020] [Indexed: 06/11/2023]
Abstract
Many factors, including the inner status of the individuals and external environment, can influence the parasite infections and stress physiology in mammals. Here, we explored the influence of the sex, age, reproductive season and seasonal food availability on the parasitism and stress physiology in wild giant pandas (Ailuropoda melanoleuca) through nutrient and steroid hormone analysis and parasitic infection measurement. Diet composition had significant influences on the faecal cortisol levels and parasite load of wild giant pandas. The seasonal dynamic of the cortisol levels and parasite load in faeces co-vary with the seasonal nutrient intake levels of the pandas, which concurrently arrived the peaks at the wood bamboo shoot-eating period in May (parasite infection intensity, 41.47 ± 12.11 eggs/g of wet faeces; cortisol levels, 619.34 ± 70.55 ng/g dry faeces) that the nutrition intake by wild pandas was the highest (protein/fibre, 69.23 ± 9.93). Meanwhile, age class is also as an important factor to affect the parasite load and stress physiology of wild giant pandas. Cubs and sub-adults suffered more helminth burden and stress physiology than adults and old individuals. This is the first study to evaluate the inner and external factors influence on parasitism and stress physiology in wild giant pandas. The findings facilitate a better understanding of how environmental factors might influence the physiology, behaviour and health of pandas and other species and have implications for the conservation and management of the endangered species.
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Affiliation(s)
- Wenliang Zhou
- Key Laboratory of Animal Ecology and Conservation Biology, Institute of Zoology, Chinese Academy of Sciences, Beijing 100101, China
| | - Kai Gao
- Ministry of Education, Key Laboratory for Biodiversity Science and Ecological Engineering, College of Life Sciences, Beijing Normal University, Beijing 100875, China
| | - Yingjie Ma
- Key Laboratory of Animal Ecology and Conservation Biology, Institute of Zoology, Chinese Academy of Sciences, Beijing 100101, China
- University of Chinese Academy of Sciences, Beijing 100049, China
| | - Le Wang
- Key Laboratory of Animal Ecology and Conservation Biology, Institute of Zoology, Chinese Academy of Sciences, Beijing 100101, China
- University of Chinese Academy of Sciences, Beijing 100049, China
| | - Meng Wang
- Key Laboratory of Animal Ecology and Conservation Biology, Institute of Zoology, Chinese Academy of Sciences, Beijing 100101, China
- University of Chinese Academy of Sciences, Beijing 100049, China
| | - Fuwen Wei
- Key Laboratory of Animal Ecology and Conservation Biology, Institute of Zoology, Chinese Academy of Sciences, Beijing 100101, China
- University of Chinese Academy of Sciences, Beijing 100049, China
- Center for Excellence in Animal Evolution and Genetics, Chinese Academy of Sciences, Kunming 650223, China
| | - Yonggang Nie
- Key Laboratory of Animal Ecology and Conservation Biology, Institute of Zoology, Chinese Academy of Sciences, Beijing 100101, China
- University of Chinese Academy of Sciences, Beijing 100049, China
- Center for Excellence in Animal Evolution and Genetics, Chinese Academy of Sciences, Kunming 650223, China
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Alekseeva GS, Loshchagina JA, Erofeeva MN, Naidenko SV. Stressed by Maternity: Changes of Cortisol Level in Lactating Domestic Cats. Animals (Basel) 2020; 10:ani10050903. [PMID: 32456071 PMCID: PMC7278448 DOI: 10.3390/ani10050903] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2020] [Revised: 05/17/2020] [Accepted: 05/19/2020] [Indexed: 12/18/2022] Open
Abstract
Lactation is the most energetically expensive component of maternal care in mammals. Increased reproductive investment can lead to physiological stress for the mothers, based on the exhaustion of energy resources and increase in glucocorticoids level. This study aimed to estimate the changes in cortisol concentrations during lactation in domestic cats and compared the differences among litter sizes. Eleven females gave birth to 27 litters, which were divided in two groups-small (1-3 kittens) and large (4-7 kittens) litters. Blood samples were collected from each female before mating, after parturition, at 4 and 8 weeks of lactation. We showed that the cortisol level in females changed significantly during lactation-the highest concentrations were observed at the peak of lactation at 4 weeks. Cortisol levels varied significantly among females but did not depend on their maternal experience. We also revealed that there were no differences in cortisol levels between females with small and large litters, but at 4 weeks of lactation, the hormone concentrations were higher in females with small litters. It is likely that these females initially invested less in reproduction, giving birth to fewer offspring.
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Affiliation(s)
- Galina S. Alekseeva
- A.N. Severtsov Institute of Ecology and Evolution, Russian Academy of Sciences, 119071 Moscow, Russia; (M.N.E.); (S.V.N.)
- Correspondence:
| | | | - Mariya N. Erofeeva
- A.N. Severtsov Institute of Ecology and Evolution, Russian Academy of Sciences, 119071 Moscow, Russia; (M.N.E.); (S.V.N.)
| | - Sergey V. Naidenko
- A.N. Severtsov Institute of Ecology and Evolution, Russian Academy of Sciences, 119071 Moscow, Russia; (M.N.E.); (S.V.N.)
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Komar E, Dechmann DKN, Fasel NJ, Zegarek M, Ruczyński I. Food restriction delays seasonal sexual maturation but does not increase torpor use in male bats. J Exp Biol 2020; 223:jeb214825. [PMID: 32165436 DOI: 10.1242/jeb.214825] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2019] [Accepted: 03/04/2020] [Indexed: 12/29/2022]
Abstract
Balancing energy budgets can be challenging, especially in periods of food shortage, adverse weather conditions and increased energy demand due to reproduction. Bats have particularly high energy demands compared to other mammals and regularly use torpor to save energy. However, while torpor limits energy expenditure, it can also downregulate important processes, such as sperm production. This constraint could result in a trade-off between energy saving and future reproductive capacity. We mimicked harsh conditions by restricting food and tested the effect on changes in body mass, torpor use and seasonal sexual maturation in male parti-coloured bats (Vespertilio murinus). Food-restricted individuals managed to maintain their initial body mass, while in well-fed males, mass increased. Interestingly, despite large differences in food availability, there were only small differences in torpor patterns. However, well-fed males reached sexual maturity up to half a month earlier. Our results thus reveal a complex trade-off in resource allocation; independent of resource availability, males maintain a similar thermoregulation strategy and favour fast sexual maturation, but limited resources and low body mass moderate this latter process.
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Affiliation(s)
- Ewa Komar
- Mammal Research Institute, Polish Academy of Sciences, Stoczek, 17-230 Białowieża, Poland
| | - Dina K N Dechmann
- Max Planck Institute of Animal Behavior, Am Obstberg 1, D-78315 Radolfzell, Germany
- Department of Biology, University of Konstanz, Universitätsstraße 10, D-78457 Konstanz, Germany
| | - Nicolas J Fasel
- Department of Ecology and Evolution, University of Lausanne, Biophore, 1015 Lausanne, Switzerland
| | - Marcin Zegarek
- Mammal Research Institute, Polish Academy of Sciences, Stoczek, 17-230 Białowieża, Poland
| | - Ireneusz Ruczyński
- Mammal Research Institute, Polish Academy of Sciences, Stoczek, 17-230 Białowieża, Poland
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Ferguson SH, Yurkowski DJ, Young BG, Willing C, Zhu X, Muir DCG, Fisk AT, Thiemann GW. Do intraspecific life history patterns follow interspecific predictions? A test using latitudinal variation in ringed seals. POPUL ECOL 2019. [DOI: 10.1002/1438-390x.12008] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Affiliation(s)
- Steven H. Ferguson
- Department of Fisheries and Oceans Canada Winnipeg Manitoba Canada
- Department of Biological Sciences University of Manitoba Winnipeg Manitoba Canada
| | - David J. Yurkowski
- Department of Fisheries and Oceans Canada Winnipeg Manitoba Canada
- Department of Biological Sciences University of Manitoba Winnipeg Manitoba Canada
| | - Brent G. Young
- Department of Fisheries and Oceans Canada Winnipeg Manitoba Canada
| | - Cornelia Willing
- Department of Biological Sciences University of Manitoba Winnipeg Manitoba Canada
- Centre for Earth Observation Science University of Manitoba Winnipeg Manitoba Canada
| | - Xinhua Zhu
- Department of Fisheries and Oceans Canada Winnipeg Manitoba Canada
- Great Lakes Institute for Environmental Research University of Windsor Windsor Ontario Canada
| | - Derek C. G. Muir
- Environment and Climate Change Canada Aquatic Contaminants Research Division Burlington Ontario Canada
| | - Aaron T. Fisk
- Great Lakes Institute for Environmental Research University of Windsor Windsor Ontario Canada
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DeRango EJ, Prager KC, Greig DJ, Hooper AW, Crocker DE. Climate variability and life history impact stress, thyroid, and immune markers in California sea lions ( Zalophus californianus) during El Niño conditions. CONSERVATION PHYSIOLOGY 2019; 7:coz010. [PMID: 31110762 PMCID: PMC6518924 DOI: 10.1093/conphys/coz010] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/26/2018] [Revised: 01/07/2019] [Accepted: 03/18/2019] [Indexed: 05/02/2023]
Abstract
Wildlife is exposed to a diverse set of extrinsic and intrinsic stressors, such as climatic variation or life history constraints, which may impact individual health and fitness. El Niño and climatic anomalies between 2013 and 2016 had major ecological impacts on the California Current ecosystem. As top marine predators, California sea lions (CSL) experienced decreased prey availability and foraging success, impacting their nutritional state. We hypothesize that chronic stress to juvenile CSL increased during the 2015-2016 El Niño and that breeding represents a period of chronic stress for adults, which impact a variety of physiological processes. We opportunistically captured and sampled juvenile CSL (female, n = 29; male, n = 38) in central California and adult male CSL (n = 76) in Astoria, Oregon and quantified a suite of analytes in serum as indicators of acute stress markers, metabolism and thyroid function, and adaptive immune response. We found that stress hormones and glucose were decreased in juvenile CSL during 2016 relative to 2015 and in adult male CSL after the breeding season, which may indicate chronic stress downregulating HPA (hypothalamic-pituitary-adrenal) axis sensitivity with associated metabolic impacts. Conversely, thyroid hormones for both juvenile and adult male CSL were increased, suggesting greater energetic requirements resulting from increased foraging activity during suboptimal conditions in juveniles and breeding tenure in adult males. Immunoglobulin IgG was elevated in juveniles in 2016 but reduced in adult males post-breeding. This suggests that juveniles may face immunostimulatory pressure during anomalously warm ocean environments; however, for adult males, breeding is a significant energetic cost resulting in reductions to immune function. Our results indicate that environmental conditions and life history stage may influence physiological responses in an important marine predator and a sentinel species of changing ocean ecosystems.
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Affiliation(s)
- Eugene J DeRango
- Department of Biology, Sonoma State University, Rohnert Park, CA, USA
- Department of Animal Behaviour, Bielefeld University, Bielefeld, Germany
- Corresponding author: Department of Biology, Sonoma State University, 1801 E Cotati Ave, Rohnert Park, CA 94928, USA. Tel: +1-708-299-4366.
| | - Katherine C Prager
- Department of Ecology and Evolutionary Biology, University of California Los Angeles, Los Angeles, CA, USA
| | - Denise J Greig
- Ornithology and Mammalogy Department, California Academy of Sciences, San Francisco, CA, USA
| | - Amanda W Hooper
- Department of Biology, Sonoma State University, Rohnert Park, CA, USA
| | - Daniel E Crocker
- Department of Biology, Sonoma State University, Rohnert Park, CA, USA
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