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LaDage LD, McCormick GL, Robbins TR, Longwell AS, Langkilde T. The effects of early-life and intergenerational stress on the brain. Proc Biol Sci 2023; 290:20231356. [PMID: 38018110 PMCID: PMC10685117 DOI: 10.1098/rspb.2023.1356] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2023] [Accepted: 11/07/2023] [Indexed: 11/30/2023] Open
Abstract
Stress experienced during ontogeny can have profound effects on the adult phenotype. However, stress can also be experienced intergenerationally, where an offspring's phenotype can be moulded by stress experienced by the parents. Although early-life and intergenerational stress can alter anatomy, physiology, and behaviour, nothing is known about how these stress contexts interact to affect the neural phenotype. Here, we examined how early-life and intergenerational stress affect the brain in eastern fence lizards (Sceloporus undulatus). Some lizard populations co-occur with predatory fire ants, and stress from fire ant attacks exerts intergenerational physiological and behavioural changes in lizards. However, it is unclear if intergenerational stress, or the interaction between intergenerational and early-life stress, modulates the brain. To test this, we captured gravid females from fire ant invaded and uninvaded populations, and subjected offspring to three early-life stress treatments: (1) fire ant attack, (2) corticosterone, or (3) a control. Corticosterone and fire ant attack decreased some aspects of the neural phenotype while population of origin and the interaction of early-life stress and population had no effects on the brain. These results suggest that early-life stressors may better predict adult brain variation than intergenerational stress in this species.
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Affiliation(s)
- Lara D. LaDage
- Division of Mathematics & Natural Sciences, Penn State Altoona, 3000 Ivyside Dr., Altoona, PA 16601, USA
| | - Gail L. McCormick
- Eberly College of Science, Pennsylvania State University, University Park, PA 16802, USA
| | - Travis R. Robbins
- Department of Biology, University of Nebraska Omaha, 6001 Dodge St., Omaha, NE 68182, USA
| | - Anna S. Longwell
- Division of Mathematics & Natural Sciences, Penn State Altoona, 3000 Ivyside Dr., Altoona, PA 16601, USA
| | - Tracy Langkilde
- Eberly College of Science, Pennsylvania State University, University Park, PA 16802, USA
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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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Hammond TT, Ortiz-Jimenez CA, Smith JE. Anthropogenic Change Alters Ecological Relationships via Interactive Changes in Stress Physiology and Behavior within and among Organisms. Integr Comp Biol 2020; 60:57-69. [PMID: 31960928 DOI: 10.1093/icb/icaa001] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Anthropogenic change has well-documented impacts on stress physiology and behavior across diverse taxonomic groups. Within individual organisms, physiological and behavioral traits often covary at proximate and ultimate timescales. In the context of global change, this means that impacts on physiology can have downstream impacts on behavior, and vice versa. Because all organisms interact with members of their own species and other species within their communities, the effects of humans on one organism can impose indirect effects on one or more other organisms, resulting in cascading effects across interaction networks. Human-induced changes in the stress physiology of one species and the downstream impacts on behavior can therefore interact with the physiological and behavioral responses of other organisms to alter emergent ecological phenomena. Here, we highlight three scenarios in which the stress physiology and behavior of individuals on different sides of an ecological relationship are interactively impacted by anthropogenic change. We discuss host-parasite/pathogen dynamics, predator-prey relationships, and beneficial partnerships (mutualisms and cooperation) in this framework, considering cases in which the effect of stressors on each type of network may be attenuated or enhanced by interactive changes in behavior and physiology. These examples shed light on the ways that stressors imposed at the level of one individual can impact ecological relationships to trigger downstream consequences for behavioral and ecological dynamics. Ultimately, changes in stress physiology on one or both sides of an ecological interaction can mediate higher-level population and community changes due in part to their cascading impacts on behavior. This framework may prove useful for anticipating and potentially mitigating previously underappreciated ecological responses to anthropogenic perturbations in a rapidly changing world.
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Affiliation(s)
- Talisin T Hammond
- San Diego Zoo Institute for Conservation Research, Escondido, CA 92027, USA
| | - Chelsea A Ortiz-Jimenez
- Department of Environmental Science and Policy, University of California, Davis, CA 95616, USA
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Effects of temperature on plasma corticosterone in a native lizard. Sci Rep 2020; 10:16315. [PMID: 33004871 PMCID: PMC7530705 DOI: 10.1038/s41598-020-73354-z] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2020] [Accepted: 09/15/2020] [Indexed: 12/30/2022] Open
Abstract
The glucocorticoid stress response is frequently used to indicate vertebrate response to the environment. Body temperature may affect glucocorticoid concentrations, particularly in ectotherms. We conducted lab manipulations and field measurements to test the effects of body temperature on plasma corticosterone (predominant glucocorticoid in reptiles) in eastern fence lizards (Sceloporus undulatus). First, we acclimated lizards to one of 4 treatments: 22 °C, 29 °C, 33 °C, or 36 °C, and measured cloacal temperatures and plasma corticosterone concentrations at baseline and after exposure to a standardized stressor (cloth bag). Both baseline and stress-induced corticosterone concentrations were lower in lizards with lower body temperatures. Second, we acclimated lizards to 22 °C or 29 °C and exposed them to a standardized (cloth bag) stressor for 3 to 41 min. Lizards acclimated to 29 °C showed a robust increase in plasma corticosterone concentrations with restraint stress, but those at 22 °C showed no such increases in corticosterone concentrations. Third, we measured lizards upon capture from the field. There was no correlation between body temperature and baseline plasma corticosterone in field-caught lizards. These results suggest body temperature can significantly affect plasma corticosterone concentrations in reptiles, which may be of particular concern for experiments conducted under laboratory conditions but may not translate to the field.
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Physiological Stress Integrates Resistance to Rattlesnake Venom and the Onset of Risky Foraging in California Ground Squirrels. Toxins (Basel) 2020; 12:toxins12100617. [PMID: 32992585 PMCID: PMC7601495 DOI: 10.3390/toxins12100617] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2020] [Revised: 09/22/2020] [Accepted: 09/23/2020] [Indexed: 12/17/2022] Open
Abstract
Using venom for predation often leads to the evolution of resistance in prey. Understanding individual variation in venom resistance is key to unlocking basic mechanisms by which antagonistic coevolution can sustain variation in traits under selection. For prey, the opposing challenges of predator avoidance and resource acquisition often lead to correlated levels of risk and reward, which in turn can favor suites of integrated morphological, physiological and behavioral traits. We investigate the relationship between risk-sensitive behaviors, physiological resistance to rattlesnake venom, and stress in a population of California ground squirrels. For the same individuals, we quantified foraging decisions in the presence of snake predators, fecal corticosterone metabolites (a measure of “stress”), and blood serum inhibition of venom enzymatic activity (a measure of venom resistance). Individual responses to snakes were repeatable for three measures of risk-sensitive behavior, indicating that some individuals were consistently risk-averse whereas others were risk tolerant. Venom resistance was lower in squirrels with higher glucocorticoid levels and poorer body condition. Whereas resistance failed to predict proximity to and interactions with snake predators, individuals with higher glucocorticoid levels and in lower body condition waited the longest to feed when near a snake. We compared alternative structural equation models to evaluate alternative hypotheses for the relationships among stress, venom resistance, and behavior. We found support for stress as a shared physiological correlate that independently lowers venom resistance and leads to squirrels that wait longer to feed in the presence of a snake, whereas we did not find evidence that resistance directly facilitates latency to forage. Our findings suggest that stress may help less-resistant squirrels avoid a deadly snakebite, but also reduces feeding opportunities. The combined lethal and non-lethal effects of stressors in predator–prey interactions simultaneously impact multiple key traits in this system, making environmental stress a potential contributor to geographic variation in trait expression of toxic predators and resistant prey.
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Assis BA, Jarrett BJM, Koscky G, Langkilde T, Avery JD. Plastic sexual ornaments: Assessing temperature effects on color metrics in a color-changing reptile. PLoS One 2020; 15:e0233221. [PMID: 32433700 PMCID: PMC7239470 DOI: 10.1371/journal.pone.0233221] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2019] [Accepted: 04/30/2020] [Indexed: 11/19/2022] Open
Abstract
Conspicuous coloration is an important subject in social communication and animal behavior, and it can provide valuable insight into the role of visual signals in social selection. However, animal coloration can be plastic and affected by abiotic factors such as temperature, making its quantification problematic. In such cases, careful consideration is required so that metric choices are consistent across environments and least sensitive to abiotic factors. A detailed assessment of plastic trait in response to environmental conditions could help identify more robust methods for quantifying color. Temperature affects sexual ornamentation of eastern fence lizards, Sceloporus undulatus, with ventral coloration shifting from green to blue hues as temperatures rise, making the calculation of saturation (color purity) difficult under conditions where temperatures vary. We aimed to characterize how abiotic factors influence phenotypic expression and to identify a metric for quantifying animal color that is either independent from temperature (ideally) or best conserves individual's ranks. We compared the rates of change in saturation across two temperature treatments using seven metrics: three that are based on fixed spectral ranges (with two of them designed by us specifically for this system) and three that track the expressed hue (with one of them designed by us to circumvent spurious results in unornamented individuals). We also applied a lizard visual sensitivity model to understand how temperature-induced color changes may be perceived by conspecifics. We show that the rate of change in saturation between two temperatures is inconsistent across individuals, increasing at a higher rate in individuals with higher baseline saturation at lower temperatures. In addition, the relative color rank of individuals in a population varies with the temperature standardized by the investigator, but more so for some metrics than others. While we were unable to completely eliminate the effect of temperature, current tools for quantifying color allowed us to use spectral data to estimate saturation in a variety of ways and to largely preserve saturation ranks of individuals across temperatures while avoiding erroneous color scores. We describe our approaches and suggest best-practices for quantifying and interpreting color, particularly in cases where color changes in response to environmental factors.
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Affiliation(s)
- Braulio A. Assis
- Department of Biology, Intercollege Graduate Degree Program in Ecology, The Pennsylvania State University, University Park, PA, United States of America
| | - Benjamin J. M. Jarrett
- Department of Entomology, Michigan State University, East Lansing, MI, United States of America
| | - Gabe Koscky
- Independent scholar, New York, NY, United States of America
| | - Tracy Langkilde
- Department of Biology, Intercollege Graduate Degree Program in Ecology, The Pennsylvania State University, University Park, PA, United States of America
| | - Julian D. Avery
- The Department of Ecosystem Science and Management, The Pennsylvania State University, University Park, PA, United States of America
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Sprayberry K, Tylan C, Owen DAS, Macleod KJ, Sheriff MJ, Langkilde T. History of predator exposure affects cell-mediated immunity in female eastern fence lizards, Sceloporus undulatus (Squamata: Phrynosomatidae). Biol J Linn Soc Lond 2019. [DOI: 10.1093/biolinnean/blz154] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
Abstract
On exposure to stressors, energy is diverted from non-urgent functions towards those important for immediate survival. The degree and nature of reallocation may be affected by the evolutionary history of the animal. The eastern fence lizard (Sceloporus undulatus) coexists in parts of its range with invasive fire ants (Solenopsis invicta), which attack and wound lizards and elevate stress-relevant hormones (corticosterone), whereas other populations have never been exposed to fire ants. We examined how a history of fire ant invasion affected the immune response in female lizards after exposure to exogenous corticosterone (mimicking exposure to a stressor) during gestation (dosing regimens differed among corticosterone-exposed lizards owing to the constraints of the original studies, but we found no evidence that this affected the outcome of the present study). A history of exposure to predatory stressors (fire ants) and corticosterone treatment affected cell-mediated immunity. Lizards from fire ant-invaded sites had a reduced immune response compared with those from uninvaded sites. Corticosterone treatment had no effect on the immune response of lizards from invaded sites but reduced the immune response of lizards from uninvaded sites. This suggests that an evolutionary history of exposure to wounding alters the immune response to corticosterone. Future work on how the immune system responds to environmental threats will be informative for the prediction and management of these threats.
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Affiliation(s)
- Kristen Sprayberry
- Department of Veterinary and Biomedical Sciences, The Pennsylvania State University, University Park, USA
| | - Catherine Tylan
- Department of Biology, The Pennsylvania State University, University Park, USA
| | - Dustin A S Owen
- Department of Biology, The Pennsylvania State University, University Park, USA
- Department of Ecosystem Science and Management, The Pennsylvania State University, University Park, USA
- Intercollege Graduate Degree Program in Ecology, The Pennsylvania State University, University Park, USA
| | - Kirsty J Macleod
- Department of Biology, The Pennsylvania State University, University Park, USA
- Department of Ecosystem Science and Management, The Pennsylvania State University, University Park, USA
- Intercollege Graduate Degree Program in Ecology, The Pennsylvania State University, University Park, USA
| | - Michael J Sheriff
- Department of Ecosystem Science and Management, The Pennsylvania State University, University Park, USA
- Intercollege Graduate Degree Program in Ecology, The Pennsylvania State University, University Park, USA
| | - Tracy Langkilde
- Department of Biology, The Pennsylvania State University, University Park, USA
- Intercollege Graduate Degree Program in Ecology, The Pennsylvania State University, University Park, USA
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