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Field EK, Terry J, Hartzheim AM, Krajcir K, Mullin SJ, Neuman-Lee LA. Investigating relationships among stress, reproduction, and immunity in three species of watersnake. Gen Comp Endocrinol 2023; 343:114350. [PMID: 37524232 DOI: 10.1016/j.ygcen.2023.114350] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/21/2023] [Revised: 07/06/2023] [Accepted: 07/27/2023] [Indexed: 08/02/2023]
Abstract
Energy is a finite resource required for all physiological processes and must be allocated efficiently among essential activities to ensure fitness and survival. During the active season, adult organisms are expected to prioritize investment in reproduction over other energetically expensive processes, such as responding to immunological challenges. Furthermore, when encountering a stressor, the balance between reproduction and immunity might be disrupted in order to fuel the stress response. Because of the distinct differences in life histories across species, watersnakes provide a unique group of study in which to examine these tradeoffs. Over a two-year period, we captured three watersnake species throughout Northeast Arkansas. Animals were subjected to restraint stress and blood samples were collected throughout the acute stress response. Blood samples were used to assess innate immunity and steroid hormone concentrations. We found the peak in corticosterone concentration is season-specific, potentially because energetic reserves fluctuate with reproductive activities. We also found body condition was positively related to acute stress and negatively related to immunity. Watersnakes evidently prioritize reproduction over immunity, especially during the energetically intensive process of vitellogenesis. Energetic tradeoffs between reproduction, immunity, and the stress response are complex, and this study contributes to our understanding of energetic shifts in free-living organisms in the context of stress.
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Affiliation(s)
- Emily K Field
- Department of Biological Sciences, Arkansas State University, Jonesboro, AR, United States; Mississippi Department of Wildlife, Fisheries, and Parks, Mississippi Museum of Natural Science, Jackson MS, United States.
| | - Jennifer Terry
- Department of Biological Sciences, Arkansas State University, Jonesboro, AR, United States
| | - Alyssa M Hartzheim
- Department of Biological Sciences, Arkansas State University, Jonesboro, AR, United States; North Carolina Museum of Natural Sciences, Raleigh, NC, United States
| | - Kevin Krajcir
- Department of Biological Sciences, Arkansas State University, Jonesboro, AR, United States; Arkansas Natural Heritage Commission, Little Rock, AR, United States
| | - Stephen J Mullin
- Department of Biological Sciences, Arkansas State University, Jonesboro, AR, United States.
| | - Lorin A Neuman-Lee
- Department of Biological Sciences, Arkansas State University, Jonesboro, AR, United States.
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Bronikowski AM, Hedrick AR, Kutz GA, Holden KG, Reinke B, Iverson JB. Sex-specific innate immunity and ageing in long-lived fresh water turtles (Kinosternon flavescens: Kinosternidae). Immun Ageing 2023; 20:11. [PMID: 36894996 PMCID: PMC9997018 DOI: 10.1186/s12979-023-00335-x] [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: 11/09/2022] [Accepted: 02/27/2023] [Indexed: 03/11/2023]
Abstract
BACKGROUND The progressive deregulation of the immune system with age, termed immunosenescence, has been well studied in mammalian systems, but studies of immune function in long-lived, wild, non-mammalian populations are scarce. In this study we leverage a 38-year mark-recapture study to quantify the relationships among age, sex, survival, reproductive output and the innate immune system in a long-lived reptile, yellow mud turtles (Kinosternon flavescens; Testudines; Kinosternidae). METHODS We estimated rates of survival and age-specific mortality by sex based on mark-recapture data for 1530 adult females and 860 adult males over 38 years of captures. We analyzed bactericidal competence (BC), and two immune responses to foreign red blood cells - natural antibody-mediated haemagglutination (NAbs), and complement-mediated haemolysis ability (Lys) - in 200 adults (102 females; 98 males) that ranged from 7 to 58 years of age captured in May 2018 during their emergence from brumation, and for which reproductive output and long-term mark-recapture data were available. RESULTS We found that females are smaller and live longer than males in this population, but the rate of accelerating mortality across adulthood is the same for both sexes. In contrast, males exhibited higher innate immunity than females for all three immune variables we measured. All immune responses also varied inversely with age, indicating immunosenescence. For females that reproduced in the preceding reproductive season, egg mass (and therefore total clutch mass) increased with age,. In addition to immunosenescence of bactericidal competence, females that produced smaller clutches also had lower bactericidal competence. CONCLUSIONS Contrary to the general vertebrate pattern of lower immune responses in males than females (possibly reflecting the suppressive effects of androgens), we found higher levels of all three immune variables in males. In addition, contrary to previous work that found no evidence of immunosenescence in painted turtles or red-eared slider turtles, we found a decrease in bactericidal competence, lysis ability, and natural antibodies with age in yellow mud turtles.
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Affiliation(s)
- Anne M Bronikowski
- Department of Ecology, Evolution, and Organismal Biology, Iowa State University, Ames, IA, 50011, USA. .,Department of Integrative Biology, Kellogg Biological Station, Michigan State University, 3700 E. Gull Lake Rd., Hickory Corners, MI, 49060, USA.
| | - Ashley R Hedrick
- Department of Ecology, Evolution, and Organismal Biology, Iowa State University, Ames, IA, 50011, USA
| | - Greta A Kutz
- Department of Ecology, Evolution, and Organismal Biology, Iowa State University, Ames, IA, 50011, USA
| | - Kaitlyn G Holden
- Department of Ecology, Evolution, and Organismal Biology, Iowa State University, Ames, IA, 50011, USA
| | - Beth Reinke
- Department of Biology, Northeastern Illinois University, Chicago, IL, 60625, USA
| | - John B Iverson
- Department of Biology, Earlham College, Richmond, IN, 47374, USA.
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3
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Field EK, Hartzheim A, Terry J, Dawson G, Haydt N, Neuman-Lee LA. Reptilian Innate Immunology and Ecoimmunology: What Do We Know and Where Are We Going? Integr Comp Biol 2022; 62:1557-1571. [PMID: 35833292 DOI: 10.1093/icb/icac116] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2022] [Revised: 06/27/2022] [Accepted: 06/28/2022] [Indexed: 01/05/2023] Open
Abstract
Reptiles, the only ectothermic amniotes, employ a wide variety of physiological adaptations to adjust to their environments but remain vastly understudied in the field of immunology and ecoimmunology in comparison to other vertebrate taxa. To address this knowledge gap, we assessed the current state of research on reptilian innate immunology by conducting an extensive literature search of peer-reviewed articles published across the four orders of Reptilia (Crocodilia, Testudines, Squamata, and Rhynchocephalia). Using our compiled dataset, we investigated common techniques, characterization of immune components, differences in findings and type of research among the four orders, and immune responses to ecological and life-history variables. We found that there are differences in the types of questions asked and approaches used for each of these reptilian orders. The different conceptual frameworks applied to each group has led to a lack of unified understanding of reptilian immunological strategies, which, in turn, have resulted in large conceptual gaps in the field of ecoimmunology as a whole. To apply ecoimmunological concepts and techniques most effectively to reptiles, we must combine traditional immunological studies with ecoimmunological studies to continue to identify, characterize, and describe the reptilian immune components and responses. This review highlights the advances and gaps that remain to help identify targeted and cohesive approaches for future research in reptilian ecoimmunological studies.
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Affiliation(s)
- Emily K Field
- Department of Biological Sciences, Arkansas State University, Jonesboro, AR 72401, USA
| | - Alyssa Hartzheim
- Department of Biological Sciences, Arkansas State University, Jonesboro, AR 72401, USA
| | - Jennifer Terry
- Department of Biological Sciences, Arkansas State University, Jonesboro, AR 72401, USA
| | - Grant Dawson
- Department of Biological Sciences, Arkansas State University, Jonesboro, AR 72401, USA
| | - Natalie Haydt
- Department of Biological Sciences, Arkansas State University, Jonesboro, AR 72401, USA
| | - Lorin A Neuman-Lee
- Department of Biological Sciences, Arkansas State University, Jonesboro, AR 72401, USA
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Combrink LL, Bronikowski AM, Miller DAW, Sparkman AM. Current and time-lagged effects of climate on innate immunity in two sympatric snake species. Ecol Evol 2021; 11:3239-3250. [PMID: 33841780 PMCID: PMC8019058 DOI: 10.1002/ece3.7273] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2020] [Revised: 12/20/2020] [Accepted: 01/15/2021] [Indexed: 11/29/2022] Open
Abstract
Changing environments result in alterations at all levels of biological organization, from genetics to physiology to demography. The increasing frequency of droughts worldwide is associated with higher temperatures and reduced precipitation that can impact population persistence via effects on individual immune function and survival.We examined the effects of annual climate variation on immunity in two sympatric species of garter snakes from four populations in California over a seven-year period that included the record-breaking drought.We examined three indices of innate immunity: bactericidal competence (BC), natural antibodies (NABs), and complement-mediated lysis (CL).Precipitation was the only climatic variable explaining variation in immune function: spring precipitation of the current year was positively correlated to Thamnophis sirtalis BC and NABs, whereas spring precipitation of the previous year was positively correlated to T. elegans BC and NABs. This suggests that T. elegans experiences a physiological time-lag in response to reduced precipitation, which may reflect lack of capital for investment in immunity in the year following a dry year.In general, our findings demonstrate compelling evidence that climate can influence wild populations through effects on physiological processes, suggesting that physiological indices such as these may offer valuable opportunities for monitoring the effects of climate.
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Spence AR, French SS, Hopkins GR, Durso AM, Hudson SB, Smith GD, Neuman‐Lee LA. Long‐term monitoring of two snake species reveals immune–endocrine interactions and the importance of ecological context. JOURNAL OF EXPERIMENTAL ZOOLOGY PART 2021; 333:744-755. [DOI: 10.1002/jez.2442] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/14/2020] [Revised: 11/18/2020] [Accepted: 12/10/2020] [Indexed: 11/06/2022]
Affiliation(s)
- Austin R. Spence
- Department of Ecology and Evolutionary Biology University of Connecticut Storrs Connecticut USA
| | - Susannah S. French
- Department of Biology, Ecology Center Utah State University Logan Utah USA
| | | | - Andrew M. Durso
- Department of Biological Sciences Florida Gulf Coast University Fort Myers Florida USA
| | - Spencer B. Hudson
- Department of Biology, Ecology Center Utah State University Logan Utah USA
| | - Geoffrey D. Smith
- Department of Biological Sciences Dixie State University St. George Utah USA
| | - Lorin A. Neuman‐Lee
- Department of Biological Sciences Arkansas State University Jonesboro Arkansas USA
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Zimmerman LM. The reptilian perspective on vertebrate immunity: 10 years of progress. J Exp Biol 2020; 223:223/21/jeb214171. [DOI: 10.1242/jeb.214171] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
ABSTRACT
Ten years ago, ‘Understanding the vertebrate immune system: insights from the reptilian perspective’ was published. At the time, our understanding of the reptilian immune system lagged behind that of birds, mammals, fish and amphibians. Since then, great progress has been made in elucidating the mechanisms of reptilian immunity. Here, I review recent discoveries associated with the recognition of pathogens, effector mechanisms and memory responses in reptiles. Moreover, I put forward key questions to drive the next 10 years of research, including how reptiles are able to balance robust innate mechanisms with avoiding self-damage, how B cells and antibodies are used in immune defense and whether innate mechanisms can display the hallmarks of memory. Finally, I briefly discuss the links between our mechanistic understanding of the reptilian immune system and the field of eco-immunology. Overall, the field of reptile immunology is poised to contribute greatly to our understanding of vertebrate immunity in the next 10 years.
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Urbanization is associated with differences in age class structure in black-capped chickadees (Poecile atricapillus). Urban Ecosyst 2020. [DOI: 10.1007/s11252-020-01039-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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Palacios MG, Gangloff EJ, Reding DM, Bronikowski AM. Genetic background and thermal environment differentially influence the ontogeny of immune components during early life in an ectothermic vertebrate. J Anim Ecol 2020; 89:1883-1894. [PMID: 32472604 DOI: 10.1111/1365-2656.13271] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2020] [Accepted: 05/12/2020] [Indexed: 12/26/2022]
Abstract
An understudied aspect of vertebrate ecoimmunology has been the relative contributions of environmental factors (E), genetic background (G) and their interaction (G × E) in shaping immune development and function. Environmental temperature is known to affect many aspects of immune function and alterations in temperature regimes have been implicated in emergent disease outbreaks, making it a critical environmental factor to study in the context of immune phenotype determinants of wild animals. We assessed the relative influences of environmental temperature, genetic background and their interaction on first-year development of innate and adaptive immune defences of captive-born garter snakes Thamnophis elegans using a reciprocal transplant laboratory experiment. We used a full-factorial design with snakes from two divergent life-history ecotypes, which are known to differ in immune function in their native habitats, raised under conditions mimicking the natural thermal regime-that is, warmer and cooler-of each habitat. Genetic background (ecotype) and thermal regime influenced innate and adaptive immune parameters of snakes, but in an immune-component specific manner. We found some evidence of G × E interactions but no indication of adaptive plasticity with respect to thermal environment. At the individual level, the effects of thermal environment on resource allocation decisions varied between the fast- and the slow-paced life-history ecotypes. Under warmer conditions, which increased food consumption of individuals in both ecotypes, the former invested mostly in growth, whereas the latter invested more evenly between growth and immune development. Overall, immune parameters were highly flexible, but results suggest that other environmental factors are likely more important than temperature per se in driving the ecotype differences in immunity previously documented in the snakes under field conditions. Our results also add to the understanding of investment in immune development and growth during early postnatal life under different thermal environments. Our finding of immune-component specific patterns strongly cautions against oversimplification of the highly complex immune system in ecoimmunological studies. In conjunction, these results deepen our understanding of the degree of immunological flexibility wild animals present, information that is ever more vital in the context of rapid global environmental change.
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Affiliation(s)
- Maria G Palacios
- Department of Ecology, Evolution, and Organismal Biology, Iowa State University, Ames, IA, USA
| | - Eric J Gangloff
- Department of Ecology, Evolution, and Organismal Biology, Iowa State University, Ames, IA, USA
| | - Dawn M Reding
- Department of Ecology, Evolution, and Organismal Biology, Iowa State University, Ames, IA, USA
| | - Anne M Bronikowski
- Department of Ecology, Evolution, and Organismal Biology, Iowa State University, Ames, IA, USA
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Judson JM, Reding DM, Bronikowski AM. Immunosenescence and its influence on reproduction in a long-lived vertebrate. J Exp Biol 2020; 223:jeb223057. [PMID: 32376708 PMCID: PMC7328165 DOI: 10.1242/jeb.223057] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2019] [Accepted: 05/01/2020] [Indexed: 12/20/2022]
Abstract
Immunosenescence is a well-known phenomenon in mammal systems, but its relevance in other long-lived vertebrates is less understood. Further, the influence of age and reproductive effort on immune function in long-lived species can be challenging to assess, as long-term data are scarce and it is often difficult to sample the oldest age classes. We used the painted turtle (Chrysemys picta) to test hypotheses of immunosenescence and a trade-off between reproductive output and immune function in a population of a long-lived vertebrate that has been monitored for over 30 years. These long-term data were utilized to employ a unique approach of aging turtles with mark-recapture data and population-specific growth modeling to obtain more accurate estimates of age. We analyzed natural antibodies, lysis ability and bactericidal competence in 126 individuals from 1 to 33 years of age captured during May and June 2011. Older turtles exhibited greater natural antibody levels than young individuals. Young females with large clutches exhibited greater lysis ability, while older females with large clutches had decreased lysis ability, suggesting a trade-off between reproductive output and immune function conditional upon age. However, bactericidal competence increased later in the nesting season for older females. Our study rejects the hypothesis of immunosenescence in a long-lived turtle, despite evidence of actuarial and reproductive senescence in this population. Additionally, we detected mixed evidence for a trade-off between reproduction and immune health.
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Affiliation(s)
- Jessica M Judson
- Department of Ecology, Evolution, and Organismal Biology, Iowa State University, 251 Bessey Hall, Ames, IA 50011, USA
| | - Dawn M Reding
- Department of Ecology, Evolution, and Organismal Biology, Iowa State University, 251 Bessey Hall, Ames, IA 50011, USA
| | - Anne M Bronikowski
- Department of Ecology, Evolution, and Organismal Biology, Iowa State University, 251 Bessey Hall, Ames, IA 50011, USA
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Becker DJ, Albery GF, Kessler MK, Lunn TJ, Falvo CA, Czirják GÁ, Martin LB, Plowright RK. Macroimmunology: The drivers and consequences of spatial patterns in wildlife immune defence. J Anim Ecol 2020; 89:972-995. [PMID: 31856309 DOI: 10.1111/1365-2656.13166] [Citation(s) in RCA: 59] [Impact Index Per Article: 14.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2019] [Accepted: 11/06/2019] [Indexed: 01/26/2023]
Abstract
The prevalence and intensity of parasites in wild hosts varies across space and is a key determinant of infection risk in humans, domestic animals and threatened wildlife. Because the immune system serves as the primary barrier to infection, replication and transmission following exposure, we here consider the environmental drivers of immunity. Spatial variation in parasite pressure, abiotic and biotic conditions, and anthropogenic factors can all shape immunity across spatial scales. Identifying the most important spatial drivers of immunity could help pre-empt infectious disease risks, especially in the context of how large-scale factors such as urbanization affect defence by changing environmental conditions. We provide a synthesis of how to apply macroecological approaches to the study of ecoimmunology (i.e. macroimmunology). We first review spatial factors that could generate spatial variation in defence, highlighting the need for large-scale studies that can differentiate competing environmental predictors of immunity and detailing contexts where this approach might be favoured over small-scale experimental studies. We next conduct a systematic review of the literature to assess the frequency of spatial studies and to classify them according to taxa, immune measures, spatial replication and extent, and statistical methods. We review 210 ecoimmunology studies sampling multiple host populations. We show that whereas spatial approaches are relatively common, spatial replication is generally low and unlikely to provide sufficient environmental variation or power to differentiate competing spatial hypotheses. We also highlight statistical biases in macroimmunology, in that few studies characterize and account for spatial dependence statistically, potentially affecting inferences for the relationships between environmental conditions and immune defence. We use these findings to describe tools from geostatistics and spatial modelling that can improve inference about the associations between environmental and immunological variation. In particular, we emphasize exploratory tools that can guide spatial sampling and highlight the need for greater use of mixed-effects models that account for spatial variability while also allowing researchers to account for both individual- and habitat-level covariates. We finally discuss future research priorities for macroimmunology, including focusing on latitudinal gradients, range expansions and urbanization as being especially amenable to large-scale spatial approaches. Methodologically, we highlight critical opportunities posed by assessing spatial variation in host tolerance, using metagenomics to quantify spatial variation in parasite pressure, coupling large-scale field studies with small-scale field experiments and longitudinal approaches, and applying statistical tools from macroecology and meta-analysis to identify generalizable spatial patterns. Such work will facilitate scaling ecoimmunology from individual- to habitat-level insights about the drivers of immune defence and help predict where environmental change may most alter infectious disease risk.
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Affiliation(s)
- Daniel J Becker
- Department of Biology, Indiana University, Bloomington, IN, USA.,Center for the Ecology of Infectious Disease, University of Georgia, Athens, GA, USA
| | - Gregory F Albery
- Department of Biology, Georgetown University, Washington, DC, USA
| | | | - Tamika J Lunn
- Environmental Futures Research Institute, Griffith University, Nathan, Queensland, Australia
| | - Caylee A Falvo
- Department of Microbiology and Immunology, Montana State University, Bozeman, MT, USA
| | - Gábor Á Czirják
- Department of Wildlife Diseases, Leibniz Institute for Zoo and Wildlife Research, Berlin, Germany
| | - Lynn B Martin
- Department of Global and Planetary Health, University of South Florida, Tampa, FL, USA
| | - Raina K Plowright
- Department of Microbiology and Immunology, Montana State University, Bozeman, MT, USA
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Hoekstra LA, Schwartz TS, Sparkman AM, Miller DAW, Bronikowski AM. The untapped potential of reptile biodiversity for understanding how and why animals age. Funct Ecol 2020; 34:38-54. [PMID: 32921868 PMCID: PMC7480806 DOI: 10.1111/1365-2435.13450] [Citation(s) in RCA: 32] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2019] [Accepted: 09/03/2019] [Indexed: 12/12/2022]
Abstract
1. The field of comparative aging biology has greatly expanded in the past 20 years. Longitudinal studies of populations of reptiles with a range of maximum lifespans have accumulated and been analyzed for evidence of mortality senescence and reproductive decline. While not as well represented in studies of amniote senescence, reptiles have been the subjects of many recent demographic and mechanistic studies of the biology of aging. 2. We review recent literature on reptile demographic senescence, mechanisms of senescence, and identify unanswered questions. Given the ecophysiological and demographic diversity of reptiles, what is the expected range of reptile senescence rates? Are known mechanisms of aging in reptiles consistent with canonical hallmarks of aging in model systems? What are the knowledge gaps in our understanding of reptile aging? 3. We find ample evidence of increasing mortality with advancing age in many reptiles. Testudines stand out as slower aging than other orders, but data on crocodilians and tuatara are sparse. Sex-specific analyses are generally not available. Studies of female reproduction suggest that reptiles are less likely to have reproductive decline with advancing age than mammals. 4. Reptiles share many physiological and molecular pathways of aging with mammals, birds, and laboratory model organisms. Adaptations related to stress physiology coupled with reptilian ectothermy suggest novel comparisons and contrasts that can be made with canonical aging phenotypes in mammals. These include stem cell and regeneration biology, homeostatic mechanisms, IIS/TOR signaling, and DNA repair. 5. To overcome challenges to the study of reptile aging, we recommend extending and expanding long-term monitoring of reptile populations, developing reptile cell lines to aid cellular biology, conducting more comparative studies of reptile morphology and physiology sampled along relevant life-history axes, and sequencing more reptile genomes for comparative genomics. Given the diversity of reptile life histories and adaptations, achieving these directives will likely greatly benefit all aging biology.
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Affiliation(s)
- Luke A Hoekstra
- Department of Ecology, Evolution, and Organismal Biology, Iowa State University, Ames, Iowa, 50010, USA
| | - Tonia S Schwartz
- Department of Biological Sciences, Auburn University, Auburn, Alabama 36849, USA
| | - Amanda M Sparkman
- Department of Biology, Westmont College, Santa Barbara, California, 93108, USA
| | - David A W Miller
- Department of Ecosystem Science and Management, Pennsylvania State University, University Park, PA 16802, USA
| | - Anne M Bronikowski
- Department of Ecology, Evolution, and Organismal Biology, Iowa State University, Ames, Iowa, 50010, USA
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Sandfoss MR, Claunch NM, Stacy NI, Romagosa CM, Lillywhite HB. A tale of two islands: evidence for impaired stress response and altered immune functions in an insular pit viper following ecological disturbance. CONSERVATION PHYSIOLOGY 2020; 8:coaa031. [PMID: 32382421 PMCID: PMC7196672 DOI: 10.1093/conphys/coaa031] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/20/2019] [Revised: 01/30/2020] [Accepted: 03/18/2020] [Indexed: 05/16/2023]
Abstract
The frequency and intensity of ecological perturbations affecting wild animal populations is expected to increase in the future with animals facing numerous global threats. Seahorse Key is a continental island off mainland Florida that has historically been a major rookery for several species of waterbirds. As a result of an unknown disturbance, the entire rookery abandoned Seahorse Key in April 2015 and shifted nesting activities to nearby Snake Key, resulting in an influx of food resources in the form of fish carrion to resident Florida cottonmouth snakes (Agkistrodon conanti), while snakes on Seahorse Key experienced a drastic reduction in food resources. Our objective was to assess plasma corticosterone concentrations, corticosterone negative feedback using dexamethasone, blood glucose, body condition, packed cell volume, natural antibody agglutination, white blood cell counts and ratios and erythrocyte sedimentation rate to characterize the long-term effects of differential resource availability in these two snake populations 3 years after this major ecological disturbance. We collected blood samples at three time points from cottonmouths on Seahorse Key (n = 6 individuals) and Snake Key (n = 13 individuals) in fall 2018. In due consideration of the small sample size, our study shows evidence that 3 years after the shift in waterbird nesting Seahorse Key cottonmouths exhibit a dampened acute stress response and presumptive impaired innate immune functions relative to cottonmouths on Snake Key. These results highlight the context-dependent nature of biomarkers and implicate the significant decrease in food resources on Seahorse Key in altering hormonal stress responses and innate immune functions, possibly leading to unknown long-term downstream effects. This study assessed the response of a wild population of pit viper to ecological disturbance in situ with the aim to improve our understanding of how animals cope with such perturbations and improve our capacity to make informed decisions for conservation.
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Affiliation(s)
- Mark R Sandfoss
- Department of Biology, University of Florida, 221 Carr Hall, Gainesville, FL, 32611, USA
- Corresponding author: University of Florida, 221 Carr Hall, Gainesville, FL 32611, USA.
| | - Natalie M Claunch
- School of Natural Resources and Environment, University of Florida, 103 Black Hall, Gainesville, FL, 32611, USA
| | - Nicole I Stacy
- Aquatic, Amphibian, and Reptile Pathology Program, Department of Comparative, Diagnostic, and Population Medicine, College of Veterinary Medicine, University of Florida, 2015 SW 16th Ave, Gainesville, FL, 32610, USA
| | - Christina M Romagosa
- Department of Wildlife Ecology and Conservation, University of Florida, 110 Newins-Ziegler Hall, Gainesville, FL, 32611, USA
| | - Harvey B Lillywhite
- Department of Biology, University of Florida, 221 Carr Hall, Gainesville, FL, 32611, USA
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13
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Rádai Z, Kiss P, Nagy D, Barta Z. Antibacterial immune functions of subadults and adults in a semelparous spider. PeerJ 2019; 7:e7475. [PMID: 31660257 PMCID: PMC6815191 DOI: 10.7717/peerj.7475] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2019] [Accepted: 07/15/2019] [Indexed: 11/20/2022] Open
Abstract
Although capacity to mount an efficient immune response plays a critical role in individuals’ survival, its dynamics across ontogenetic stages is still largely unexplored. Life stage-dependent variation in the encountered diversity and prevalence of parasites were proposed to contribute to stage-dependent changes in immunity, but differences in life history objectives between developmental stages may also lead to stage-specific changes in efficiency of given immune mechanisms. The reason for this is that juveniles and subadults are unable to reproduce, therefore they invest resources mainly into survival, while adults have to partition their resources between survival and reproduction. The general trade-off between somatic maintenance and reproductive effort is expected to impair immune function. Especially so in semelparous organisms that only reproduce once throughout their lifetime, hence they do not face the trade-off between current and future reproduction. We hypothesised that in a semelparous species individuals would be characterised by decreased investment into somatic maintenance after maturation, in order to maximise their reproductive output. Accordingly, we predicted that (1) elements of somatic maintenance, such as immunity, should be relatively weaker in adults in comparison to subadults, and (2) increased reproductive investment in adults should be associated with lower immune efficiency. We quantified two markers of immunity in subadult and adult individuals of the semelparous wolf spider Pardosa agrestis (Westring, 1861), namely bacterial growth inhibition power and bacterial cell wall lytic activity. We found that subadults showed significantly higher cell wall lytic activity than adults, but the two life stages did not differ in their capacity to inhibit bacterial growth. Also, we found weaker immune measures in mated females compared to virgins. Furthermore, in mated females bacterial growth inhibition power was negatively associated with fecundity.
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Affiliation(s)
- Zoltán Rádai
- MTA-DE Behavioural Ecology Research Group, Department of Evolutionary Zoology, University of Debrecen, Debrecen, Hungary
| | - Péter Kiss
- MTA-DE Behavioural Ecology Research Group, Department of Evolutionary Zoology, University of Debrecen, Debrecen, Hungary
| | - Dávid Nagy
- MTA-DE Behavioural Ecology Research Group, Department of Evolutionary Zoology, University of Debrecen, Debrecen, Hungary
| | - Zoltán Barta
- MTA-DE Behavioural Ecology Research Group, Department of Evolutionary Zoology, University of Debrecen, Debrecen, Hungary
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Feeling the heat: Extreme temperatures compromise constitutive innate humoral immunity and skin color in a desert dwelling lizard. J Therm Biol 2019; 83:142-149. [PMID: 31331512 DOI: 10.1016/j.jtherbio.2019.05.012] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2018] [Revised: 04/30/2019] [Accepted: 05/18/2019] [Indexed: 11/21/2022]
Abstract
Environmental temperature, particularly in habitats with extreme temperature fluctuations, may shape selection pressures on life history traits. Especially in ectotherms, temperature affects performance, physiology, and in some species, skin color. Skin color can be a sexual ornament signaling the bearer's ability to resist infections, when only high-quality individuals are able to invest both in high immune defense and elaborate ornament expression. However, how the information content of these sexual traits may vary with environmental conditions has been less studied. Dickerson's collared lizard (Crotaphytus dickersonae) males are blue and have a black and white collar. This conspicuous coloration signals performance and immune response, and is related to body temperature. Here, by maintaining males at higher, lower, and mean environmental temperatures we evaluated whether temperature variation influences color and constitutive innate humoral immunity (agglutination and lysis titers, estimated through hemolysis-hemagglutination assays), and whether extreme temperatures impose trade-offs between color and humoral immunity. We found that at low and high temperature treatments males had lower agglutination and lysis titers, and at low temperature, blue chroma from the dorsum declined and males became greener. Interestingly, at low and control temperature treatments, agglutination titer and blue coloration were positively correlated, whereas high temperatures revealed a trade-off between increasing agglutination titers and displaying bluer skin color. Our results suggest that in the Dickerson collared lizard even short-term variation of environmental temperature affects performance of constitutive innate humoral immunity and the brilliant blue skin color. Particularly, high temperatures may compromise some components of male's immunity and sexual signaling.
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15
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Neuman-Lee LA, Van Wettere AJ, French SS. Interrelations among Multiple Metrics of Immune and Physiological Function in a Squamate, the Common Gartersnake (Thamnophis sirtalis). Physiol Biochem Zool 2019; 92:12-23. [PMID: 30403915 DOI: 10.1086/700396] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
The field of ecoimmunology has made it clear that individual and ecological contexts are critical for interpreting an animal's immune response. In an effort to better understand the relevance of commonly used immunological assays, we tested how different metrics of immunity and physiological function were interrelated in naturally parasitized individuals of a well-studied reptile, the common gartersnake (Thamnophis sirtalis). Overall, we found that bactericidal ability, an integrative measure of innate immunity, was often correlated with more specific immunological and physiological tests (lysis and oxidative stress) but was not related to tissue-level inflammation that was determined by histopathology. The only hematological metric that correlated with tissue-level inflammation was the prevalence of monocytes in blood smears. Finally, using histological techniques, we describe natural parasitism throughout the organ systems in these individuals, finding that neither the presence nor the burden of parasite load affected the physiological and immune metrics that we measured. By performing comprehensive assessments of physiological and immune processes, we are better able to draw conclusions about how to interpret findings from specific assays in wild organisms.
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16
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Whiting JR, Magalhaes IS, Singkam AR, Robertson S, D'Agostino D, Bradley JE, MacColl ADC. A genetics-based approach confirms immune associations with life history across multiple populations of an aquatic vertebrate (Gasterosteus aculeatus). Mol Ecol 2018; 27:3174-3191. [PMID: 29924437 PMCID: PMC6221044 DOI: 10.1111/mec.14772] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2017] [Revised: 05/10/2018] [Accepted: 05/10/2018] [Indexed: 12/15/2022]
Abstract
Understanding how wild immune variation covaries with other traits can reveal how costs and trade‐offs shape immune evolution in the wild. Divergent life history strategies may increase or alleviate immune costs, helping shape immune variation in a consistent, testable way. Contrasting hypotheses suggest that shorter life histories may alleviate costs by offsetting them against increased mortality, or increase the effect of costs if immune responses are traded off against development or reproduction. We investigated the evolutionary relationship between life history and immune responses within an island radiation of three‐spined stickleback, with discrete populations of varying life histories and parasitism. We sampled two short‐lived, two long‐lived and an anadromous population using qPCR to quantify current immune profile and RAD‐seq data to study the distribution of immune variants within our assay genes and across the genome. Short‐lived populations exhibited significantly increased expression of all assay genes, which was accompanied by a strong association with population‐level variation in local alleles and divergence in a gene that may be involved in complement pathways. In addition, divergence around the eda gene in anadromous fish is likely associated with increased inflammation. A wider analysis of 15 populations across the island revealed that immune genes across the genome show evidence of having diverged alongside life history strategies. Parasitism and reproductive investment were also important sources of variation for expression, highlighting the caution required when assaying immune responses in the wild. These results provide strong, gene‐based support for current hypotheses linking life history and immune variation across multiple populations of a vertebrate model.
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Affiliation(s)
- James R Whiting
- School of Life Sciences, University of Nottingham, University Park, Nottingham, UK.,School of Life Sciences, University of Sussex, Falmer, Brighton, UK
| | - Isabel S Magalhaes
- School of Life Sciences, University of Nottingham, University Park, Nottingham, UK.,Department of Life Sciences, Whitelands College, University of Roehampton, London, UK
| | - Abdul R Singkam
- School of Life Sciences, University of Nottingham, University Park, Nottingham, UK.,Pendidikan Biologi JPMIPA FKIP, University of Bengkulu, Bengkulu, Indonesia
| | - Shaun Robertson
- School of Life Sciences, University of Nottingham, University Park, Nottingham, UK.,Institute of Biodiversity, Animal Health and Comparative Medicine, University of Glasgow, Glasgow, UK
| | - Daniele D'Agostino
- School of Life Sciences, University of Nottingham, University Park, Nottingham, UK
| | - Janette E Bradley
- School of Life Sciences, University of Nottingham, University Park, Nottingham, UK
| | - Andrew D C MacColl
- School of Life Sciences, University of Nottingham, University Park, Nottingham, UK
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17
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Palacios MG, Bronikowski AM. Immune variation during pregnancy suggests immune component-specific costs of reproduction in a viviparous snake with disparate life-history strategies. JOURNAL OF EXPERIMENTAL ZOOLOGY PART 2017; 327:513-522. [PMID: 29356424 DOI: 10.1002/jez.2137] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/08/2017] [Revised: 11/02/2017] [Accepted: 12/02/2017] [Indexed: 11/08/2022]
Abstract
Growing evidence suggests the existence of trade-offs between immune function and reproduction in diverse taxa. Among vertebrates, however, there is still a taxonomic bias toward studies in endotherms, particularly birds. We tested the hypothesis that reproduction entails immune-related costs in the viviparous garter snake, Thamnophis elegans, from populations that exhibit two life-history strategies, termed ecotypes, with contrasting paces of life. Between the two ecotypes, we predicted lower immune function in gravid than non-gravid females of both strategies, but with relatively larger immunity costs in the ecotype that generally invests more in current reproduction. Across individuals, we predicted greater immune costs for females investing more in the present specific reproductive event (i.e., higher fecundity) irrespective of their ecotype. We assessed leukocyte profiles and measured bactericidal capacity of plasma (innate immunity) and T- and B-lymphocyte proliferation (adaptive immunity) in gravid and non-gravid females in their natural habitats. We also collected data on reproductive output from these same gravid females brought into captivity. Gravid females of both ecotypes showed lower T-lymphocyte proliferation responses to concanavalin A than non-gravid females, but no differential costs were observed between ecotypes. The remaining immune variables did not vary between gravid and non-gravid females. Among gravid females within each ecotype, those with larger reproductive output showed lower total leukocyte counts, suggesting a fecundity-dependent trade-off. Our study contributes to the comparative ecoimmunology of vertebrates by highlighting the immune component-specificity of trade-offs between reproduction and immune function and showing that costs can be fecundity-dependent in some, but not all cases.
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Affiliation(s)
- Maria G Palacios
- Department of Ecology, Evolution, and Organismal Biology, Iowa State University, Ames, Iowa
| | - Anne M Bronikowski
- Department of Ecology, Evolution, and Organismal Biology, Iowa State University, Ames, Iowa
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18
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Graham SP, Fielman KT, Mendonça MT. Thermal performance and acclimatization of a component of snake (Agkistrodon piscivorus) innate immunity. JOURNAL OF EXPERIMENTAL ZOOLOGY PART 2017; 327:351-357. [DOI: 10.1002/jez.2083] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/12/2017] [Revised: 06/22/2017] [Accepted: 06/26/2017] [Indexed: 11/07/2022]
Affiliation(s)
| | - Kevin T. Fielman
- Department of Biological Sciences; Auburn University; Auburn AL USA
| | - Mary T. Mendonça
- Department of Biological Sciences; Auburn University; Auburn AL USA
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19
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Beck ML, Thompson M, Hopkins WA. Repeatability and sources of variation of the bacteria-killing assay in the common snapping turtle. JOURNAL OF EXPERIMENTAL ZOOLOGY PART 2017; 327:293-301. [PMID: 29356460 DOI: 10.1002/jez.2089] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/01/2017] [Revised: 06/16/2017] [Accepted: 07/10/2017] [Indexed: 01/13/2023]
Abstract
Research on reptile ecoimmunology lags behind that on other vertebrates, despite the importance of such studies for conservation and evolution. Because the innate immune system is highly conserved across vertebrate lineages, assessments of its performance may be particularly useful in reptiles. The bacteria-killing assay requires a single, small blood sample and quantifies an individual's ability to kill microorganisms. The assay's construct validity and interpretability make it an attractive measure of innate immunity, but it requires proper optimization and sample storage. We optimized this assay for the common snapping turtle (Chelydra serpentina) to assess the repeatability of the assay and the effects of freezing and thawing on bactericidal capacity. We determined whether age (adult female and hatchlings) or incubation temperature influenced bactericidal capacity. We found that the assay was repeatable and that freezing plasma samples for 6 weeks at -80°C did not decrease bactericidal capacity nor did a single 30-min thaw and subsequent refreezing. However, we detected subtle interassay variation and results from one assay were 5-6% greater than those from the other two. Adult females had significantly greater bactericidal ability than hatchlings and we found no relationship between incubation temperature and bactericidal capacity. This assay is a useful tool in snapping turtles and may have applicability in other reptiles. However, species-specific optimization is required to ensure that variation among individuals exceeds interassay variation. Consideration should be given to optimization conditions that facilitate comparisons between or within groups, particularly groups that differ considerably in bactericidal capacity.
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Affiliation(s)
- Michelle L Beck
- Department of Fish and Wildlife Conservation, Virginia Tech, Blacksburg, Virginia
| | - Molly Thompson
- Department of Fish and Wildlife Conservation, Virginia Tech, Blacksburg, Virginia
| | - William A Hopkins
- Department of Fish and Wildlife Conservation, Virginia Tech, Blacksburg, Virginia
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20
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Gangloff EJ, Chow M, Leos-Barajas V, Hynes S, Hobbs B, Sparkman AM. Integrating behaviour into the pace-of-life continuum: Divergent levels of activity and information gathering in fast- and slow-living snakes. Behav Processes 2017. [PMID: 28648696 DOI: 10.1016/j.beproc.2017.06.006] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Affiliation(s)
- Eric J Gangloff
- Department of Ecology, Evolution, and Organismal Biology, Iowa State University, Ames, IA 50011 USA
| | - Melinda Chow
- Department of Biology, Westmont College, Santa Barbara, CA 93108 USA
| | | | - Stephanie Hynes
- Department of Biology, Westmont College, Santa Barbara, CA 93108 USA
| | - Brooke Hobbs
- Department of Biology, Westmont College, Santa Barbara, CA 93108 USA
| | - Amanda M Sparkman
- Department of Biology, Westmont College, Santa Barbara, CA 93108 USA.
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21
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Hopkins WA, Fallon JA, Beck ML, Coe BH, Jachowski CMB. Haematological and immunological characteristics of eastern hellbenders (Cryptobranchus alleganiensis alleganiensis) infected and co-infected with endo- and ectoparasites. CONSERVATION PHYSIOLOGY 2016; 4:cow002. [PMID: 27293754 PMCID: PMC4801058 DOI: 10.1093/conphys/cow002] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/22/2015] [Revised: 12/15/2015] [Accepted: 01/04/2016] [Indexed: 05/29/2023]
Abstract
Disease is among the leading causes of the global decline in amphibian populations. In North America, parasites and pathogens are among the factors implicated in precipitous population declines of the giant hellbender salamander (Cryptobranchus alleganiensis), but the incidence of infections and the responses of hellbenders to infections remain poorly studied. Here, we document the prevalence of leech and trypanosome infections in a wild population of eastern hellbenders (Cryptobranchus alleganiensis alleganiensis) and describe haematological and immunological characteristics of hellbenders harbouring these infections. We hypothesized that hellbenders parasitized by trypanosomes would be anaemic, that individuals infected with either or both parasites would exhibit shifts in white blood cell counts and that hellbenders infected with leeches would exhibit altered plasma bactericidal capacity. We found that 24 and 68% of hellbenders in our sample population were infected with leeches and trypanosomes, respectively, and 20% were co-infected with both parasites. We found no evidence suggestive of anaemia among infected individuals. However, hellbenders infected with either or both parasites exhibited marked shifts in circulating white blood cells that were consistent with predictable responses to parasitic infection. Additionally, we found that hellbenders harbouring leeches had much higher plasma bactericidal capacity than individuals without leeches, and we offer multiple potential mechanistic explanations for this observation. We also found evidence that cellular and serological immune responses to parasites were less robust in juvenile than adult hellbenders. This finding warrants further investigation in light of the demographic characteristics, specifically the scarcity of juvenile age classes, of hellbender populations where disease is a possible contributor to declines. Finally, we describe two methodological advances that will improve future studies seeking to diagnose trypanosome infections and to test the bactericidal capacity of hellbenders and perhaps other amphibians. Our study provides fundamental insights into how hellbenders respond physiologically to endo- and ectoparasites, which could ultimately prove useful for their conservation.
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Affiliation(s)
- William A Hopkins
- Department of Fish and Wildlife Conservation, Virginia Tech, Blacksburg, VA 24061, USA
| | - Jesse A Fallon
- Department of Fish and Wildlife Conservation, Virginia Tech, Blacksburg, VA 24061, USA
| | - Michelle L Beck
- Department of Fish and Wildlife Conservation, Virginia Tech, Blacksburg, VA 24061, USA
| | - Brittney H Coe
- Department of Fish and Wildlife Conservation, Virginia Tech, Blacksburg, VA 24061, USA
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22
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Gangloff EJ, Holden KG, Telemeco RS, Baumgard LH, Bronikowski AM. Hormonal and metabolic responses to upper temperature extremes in divergent life-history ecotypes of a garter snake. J Exp Biol 2016; 219:2944-2954. [DOI: 10.1242/jeb.143107] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2016] [Accepted: 07/15/2016] [Indexed: 01/03/2023]
Abstract
Extreme temperatures constrain organismal physiology and impose both acute and chronic effects. Additionally, temperature-induced hormone-mediated stress response pathways and energetic trade-offs are important drivers of life-history variation. This study employs an integrative approach to quantify acute physiological responses to high temperatures in divergent life-history ecotypes of the western terrestrial garter snake (Thamnophis elegans). Using wild-caught animals, we measured oxygen consumption rate and physiological markers of hormonal stress response, energy availability, and anaerobic respiration in blood plasma across five ecologically relevant temperatures (24, 28, 32, 35, and 38° C; 3-hour exposure). Corticosterone, insulin, and glucose concentrations all increased with temperature, but with different thermal response curves, suggesting that high temperatures differently affect energy-regulation pathways. Additionally, oxygen consumption rate increased without plateau and lactate concentration did not increase with temperature, challenging the recent hypothesis that oxygen limitation sets upper thermal tolerance limits. Finally, animals had similar physiological thermal responses to high-temperature exposure regardless of genetic background, suggesting that local adaptation has not resulted in fixed differences between ecotypes. Together, these results identify some of the mechanisms by which higher temperatures alter hormonal-mediated energy balance in reptiles and potential limits to the flexibility of this response.
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Affiliation(s)
- Eric J. Gangloff
- Department of Ecology, Evolution, and Organismal Biology, Iowa State University, Ames, IA 50011, USA
| | - Kaitlyn G. Holden
- Department of Ecology, Evolution, and Organismal Biology, Iowa State University, Ames, IA 50011, USA
| | - Rory S. Telemeco
- Department of Ecology, Evolution, and Organismal Biology, Iowa State University, Ames, IA 50011, USA
- Present Address: Department of Biology, University of Washington, Seattle, WA 98195, USA
| | - Lance H. Baumgard
- Department of Animal Science, Iowa State University, Ames, IA 50011, USA
| | - Anne M. Bronikowski
- Department of Ecology, Evolution, and Organismal Biology, Iowa State University, Ames, IA 50011, USA
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23
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Mitochondrial divergence between slow- and fast-aging garter snakes. Exp Gerontol 2015; 71:135-46. [PMID: 26403677 DOI: 10.1016/j.exger.2015.09.004] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2015] [Revised: 09/03/2015] [Accepted: 09/04/2015] [Indexed: 01/26/2023]
Abstract
Mitochondrial function has long been hypothesized to be intimately involved in aging processes--either directly through declining efficiency of mitochondrial respiration and ATP production with advancing age, or indirectly, e.g., through increased mitochondrial production of damaging free radicals with age. Yet we lack a comprehensive understanding of the evolution of mitochondrial genotypes and phenotypes across diverse animal models, particularly in species that have extremely labile physiology. Here, we measure mitochondrial genome-types and transcription in ecotypes of garter snakes (Thamnophis elegans) that are adapted to disparate habitats and have diverged in aging rates and lifespans despite residing in close proximity. Using two RNA-seq datasets, we (1) reconstruct the garter snake mitochondrial genome sequence and bioinformatically identify regulatory elements, (2) test for divergence of mitochondrial gene expression between the ecotypes and in response to heat stress, and (3) test for sequence divergence in mitochondrial protein-coding regions in these slow-aging (SA) and fast-aging (FA) naturally occurring ecotypes. At the nucleotide sequence level, we confirmed two (duplicated) mitochondrial control regions one of which contains a glucocorticoid response element (GRE). Gene expression of protein-coding genes was higher in FA snakes relative to SA snakes for most genes, but was neither affected by heat stress nor an interaction between heat stress and ecotype. SA and FA ecotypes had unique mitochondrial haplotypes with amino acid substitutions in both CYTB and ND5. The CYTB amino acid change (Isoleucine → Threonine) was highly segregated between ecotypes. This divergence of mitochondrial haplotypes between SA and FA snakes contrasts with nuclear gene-flow estimates, but correlates with previously reported divergence in mitochondrial function (mitochondrial oxygen consumption, ATP production, and reactive oxygen species consequences).
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24
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Gangloff EJ, Vleck D, Bronikowski AM. Developmental and Immediate Thermal Environments Shape Energetic Trade-Offs, Growth Efficiency, and Metabolic Rate in Divergent Life-History Ecotypes of the Garter Snake Thamnophis elegans. Physiol Biochem Zool 2015; 88:550-63. [DOI: 10.1086/682239] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
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25
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Refsnider JM, Palacios MG, Reding DM, Bronikowski AM. Effects of a novel climate on stress response and immune function in painted turtles (Chrysemys picta). ACTA ACUST UNITED AC 2015; 323:160-8. [DOI: 10.1002/jez.1902] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2014] [Accepted: 10/06/2014] [Indexed: 01/25/2023]
Affiliation(s)
- Jeanine M. Refsnider
- Department of Ecology; Evolution and Organismal Biology; Iowa State University; Ames Iowa
| | - Maria G. Palacios
- Department of Ecology; Evolution and Organismal Biology; Iowa State University; Ames Iowa
| | - Dawn M. Reding
- Department of Ecology; Evolution and Organismal Biology; Iowa State University; Ames Iowa
| | - Anne M. Bronikowski
- Department of Ecology; Evolution and Organismal Biology; Iowa State University; Ames Iowa
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26
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Environmental proxies of antigen exposure explain variation in immune investment better than indices of pace of life. Oecologia 2014; 177:281-90. [DOI: 10.1007/s00442-014-3136-y] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2014] [Accepted: 10/24/2014] [Indexed: 10/24/2022]
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