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Surkova EN, Savinetskaya LE, Khropov IS, Tchabovsky AV. Flexible males, reactive females: faecal glucocorticoid metabolites indicate increased stress in the colonist population, damping with time in males but not in females. J Comp Physiol B 2024; 194:545-554. [PMID: 38953915 DOI: 10.1007/s00360-024-01564-2] [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: 09/26/2023] [Revised: 05/14/2024] [Accepted: 05/21/2024] [Indexed: 07/04/2024]
Abstract
Individuals colonizing new areas at expanding ranges encounter numerous and unpredictable stressors. Exposure to unfamiliar environments suggests that colonists would differ in stress levels from residents living in familiar conditions. Few empirical studies tested this hypothesis and produced mixed results, and the role of stress regulation in colonization remains unclear. Studies relating stress levels to colonization mainly use a geographical analysis comparing established colonist populations with source populations. We used faecal glucocorticoid metabolites (FGMs) to assess both spatial and temporal dynamics of stress levels in an expanding population of midday gerbils (Meriones meridianus). We demonstrated that adult males and females had higher FGM levels in newly emerged colonies, compared with the source population, but differed in the pattern of FGM dynamics post-foundation. In males, FGM levels sharply decreased in the second year after colony establishment. In females, FGM levels did not change with time and remained high despite the decreasing environmental unpredictability, exhibiting among-individual variation. Increased stress levels of colonist males damping with time post-colonization suggest they are flexible in responding to immediate changes in environmental uncertainty. On the contrary, high and stable over generations stress levels uncoupled from the changes in the environmental uncertainty in female colonists imply that they carry a relatively constant phenotype associated with the reactive coping strategy favouring colonization. We link sex differences in consistency and plasticity in stress regulation during colonization to the sex-specific life-history strategies.
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Affiliation(s)
- Elena N Surkova
- Laboratory for Population Ecology, Severtsov Institute of Ecology and Evolution, Russian Academy of Sciences, 33 Leninskii pr, Moscow, Russia
| | - Ludmila E Savinetskaya
- Laboratory for Population Ecology, Severtsov Institute of Ecology and Evolution, Russian Academy of Sciences, 33 Leninskii pr, Moscow, Russia
| | - Ivan S Khropov
- Laboratory for Population Ecology, Severtsov Institute of Ecology and Evolution, Russian Academy of Sciences, 33 Leninskii pr, Moscow, Russia
| | - Andrey V Tchabovsky
- Laboratory for Population Ecology, Severtsov Institute of Ecology and Evolution, Russian Academy of Sciences, 33 Leninskii pr, Moscow, Russia.
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2
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Siefferman L, Bentz AB, Rosvall KA. Decoupling pioneering traits from latitudinal patterns in a north American bird experiencing a southward range shift. J Anim Ecol 2023. [PMID: 36815243 DOI: 10.1111/1365-2656.13907] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2022] [Accepted: 12/12/2022] [Indexed: 02/24/2023]
Abstract
Ecogeographic rules describe spatial patterns in biological trait variation and shed light on the drivers of such variation. In animals, a consensus is emerging that 'pioneering' traits may facilitate range shifts via a set of bold, aggressive and stress-resilient traits. Many of these same traits are associated with more northern latitudes, and most range shifts in the northern hemisphere indicate northward movement. As a consequence, it is unclear whether pioneering traits are simply corollaries of existing latitudinal variation, or whether they override other well-trodden latitudinal patterning as a unique ecogeographic rule of phenotypic variation. The tree swallow Tachycineta bicolor is a songbird undergoing a southward range shift in the eastern United States, in direct opposition of the poleward movement seen in most other native species' range shifts. Because this organic range shift countervails the typical direction of movement, this case study provides for unique ecological insights on organisms and their ability to thrive in our changing world. We sampled female birds across seven populations, quantifying behavioural, physiological and morphological traits. We also used GIS and field data to quantify a core set of ecological factors with strong ties to these traits as well as female performance. Females at more southern expansion sites displayed higher maternal aggression, higher baseline corticosterone and more pronounced elevation of corticosterone following a standardized stressor, contrary to otherwise largely conserved latitudinal patterning in these traits. Microhabitat variation explained some quantitative phenotypic variation, but the expansion and historic ranges did not differ in openness, distance to water or breeding density. This countervailing range shift therefore suggests that pioneering traits are not simply corollaries of existing latitudinal variation, but rather, they may override other well-trodden latitudinal patterning as a unique ecogeographic rule of phenotypic variation.
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Affiliation(s)
- Lynn Siefferman
- Department of Biology, Appalachian State University, Boone, North Carolina, USA
| | - Alexandra B Bentz
- Department of Biology, Indiana University, Bloomington, Indiana, USA
- Department of Biology, University of Oklahoma, Norman, Oklahoma, USA
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3
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Rosvall KA. Evolutionary endocrinology and the problem of Darwin's tangled bank. Horm Behav 2022; 146:105246. [PMID: 36029721 DOI: 10.1016/j.yhbeh.2022.105246] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/12/2021] [Revised: 06/20/2022] [Accepted: 08/10/2022] [Indexed: 11/04/2022]
Abstract
Like Darwin's tangled bank of biodiversity, the endocrine mechanisms that give rise to phenotypic diversity also exhibit nearly endless forms. This tangled bank of mechanistic diversity can prove problematic as we seek general principles on the role of endocrine mechanisms in phenotypic evolution. A key unresolved question is therefore: to what degree are specific endocrine mechanisms re-used to bring about replicated phenotypic evolution? Related areas of inquiry are booming in molecular ecology, but behavioral traits are underrepresented in this literature. Here, I leverage the rich comparative tradition in evolutionary endocrinology to evaluate whether and how certain mechanisms may be repeated hotspots of behavioral evolutionary change. At one extreme, mechanisms may be parallel, such that evolution repeatedly uses the same gene or pathway to arrive at multiple independent (or, convergent) origins of a particular behavioral trait. At the other extreme, the building blocks of behavior may be unique, such that outwardly similar phenotypes are generated via lineage-specific mechanisms. This review synthesizes existing case studies, phylogenetic analyses, and experimental evolutionary research on mechanistic parallelism in animal behavior. These examples show that the endocrine building blocks of behavior have some elements of parallelism across replicated evolutionary events. However, support for parallelism is variable among studies, at least some of which relates to the level of complexity at which we consider sameness (i.e. pathway vs. gene level). Moving forward, we need continued experimentation and better testing of neutral models to understand whether, how - and critically, why - mechanism A is used in one lineage and mechanism B is used in another. We also need continued growth of large-scale comparative analyses, especially those that can evaluate which endocrine parameters are more or less likely to undergo parallel evolution alongside specific behavioral traits. These efforts will ultimately deepen understanding of how and why hormone-mediated behaviors are constructed the way that they are.
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Affiliation(s)
- Kimberly A Rosvall
- Indiana University, Bloomington, USA; Department of Biology, USA; Center for the Integrative Study of Animal Behavior, USA.
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4
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Zimmer C, Hanson HE, Martin LB. FKBP5 expression is related to HPA flexibility and the capacity to cope with stressors in female and male house sparrows. Horm Behav 2021; 135:105038. [PMID: 34280702 DOI: 10.1016/j.yhbeh.2021.105038] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/18/2021] [Revised: 07/06/2021] [Accepted: 07/08/2021] [Indexed: 12/16/2022]
Abstract
The hypothalamic-pituitary-adrenal (HPA) axis and its end products, the glucocorticoids, are critical to responding appropriately to stressors. Subsequently, many studies have sought relationships between glucocorticoids and measures of health or fitness, but such relationships are at best highly context dependent. Recently, some endocrinologists have started to suggest that a focus on HPA flexibility, the ability of an individual to mount appropriate responses to different stressors, could be useful. Here, we tested the hypothesis that expression of FKBP5, a cochaperone in the glucocorticoid receptor complex, is a simple and reliable proxy of HPA flexibility in a wild songbird, the house sparrow (Passer domesticus). We quantified HPA flexibility in a novel way, using guidance from research on heart rhythm regulation. As predicted, we found that adult sparrows with low stress-induced FKBP5 expression in the hypothalamus exhibited high HPA flexibility. Moreover, low FKBP5 expression was associated with greater exploratory disposition and were better at maintaining body mass under stressful conditions. Altogether, these results suggest that FKBP5 may be important in the regulation of HPA flexibility, potentially affecting how individuals cope with natural and anthropogenic adversity.
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Affiliation(s)
- Cedric Zimmer
- Global Health and Infectious Disease Research, University of South Florida, Tampa, FL, USA.
| | - Haley E Hanson
- Global Health and Infectious Disease Research, University of South Florida, Tampa, FL, USA
| | - Lynn B Martin
- Global Health and Infectious Disease Research, University of South Florida, Tampa, FL, USA
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5
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Baños‐Villalba A, Carrete M, Tella JL, Blas J, Potti J, Camacho C, Diop MS, Marchant TA, Cabezas S, Edelaar P. Selection on individuals of introduced species starts before the actual introduction. Evol Appl 2021; 14:781-793. [PMID: 33767752 PMCID: PMC7980263 DOI: 10.1111/eva.13159] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2020] [Revised: 09/27/2020] [Accepted: 10/01/2020] [Indexed: 11/28/2022] Open
Abstract
Biological invasion is a global problem with large negative impacts on ecosystems and human societies. When a species is introduced, individuals will first have to pass through the invasion stages of uptake and transport, before actual introduction in a non-native range. Selection is predicted to act during these earliest stages of biological invasion, potentially influencing the invasiveness and/or impact of introduced populations. Despite this potential impact of pre-introduction selection, empirical tests are virtually lacking. To test the hypothesis of pre-introduction selection, we followed the fate of individuals during capture, initial acclimation, and captivity in two bird species with several invasive populations originating from the international trade in wild-caught pets (the weavers Ploceus melanocephalus and Euplectes afer). We confirm that pre-introduction selection acts on a wide range of physiological, morphological, behavioral, and demographic traits (incl. sex, age, size of body/brain/bill, bill shape, body mass, corticosterone levels, and escape behavior); these are all traits which likely affect invasion success. Our study thus comprehensively demonstrates the existence of hitherto ignored selection acting before the actual introduction into non-native ranges. This could ultimately change the composition and functioning of introduced populations, and therefore warrants greater attention. More knowledge on pre-introduction selection also might provide novel targets for the management of invasive species, if pre-introduction filters can be adjusted to change the quality and/or quantity of individuals passing through such that invasion probability and/or impacts are reduced.
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Affiliation(s)
| | | | | | - Julio Blas
- Estación Biológica de Doñana‐CSICSevillaSpain
| | - Jaime Potti
- Estación Biológica de Doñana‐CSICSevillaSpain
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6
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Azevedo A, Bailey L, Bandeira V, Fonseca C, Wauters J, Jewgenow K. Decreasing glucocorticoid levels towards the expansion front suggest ongoing expansion in a terrestrial mammal. CONSERVATION PHYSIOLOGY 2021; 9:coab050. [PMID: 34249365 PMCID: PMC8253928 DOI: 10.1093/conphys/coab050] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/16/2021] [Revised: 06/02/2021] [Accepted: 06/11/2021] [Indexed: 05/11/2023]
Abstract
Understanding the causes of range expansions in abundant species can help predict future species distributions. During range expansions, animals are exposed to novel environments and are required to cope with new and unpredictable stressors. Glucocorticoids (GCs) are mediators of the hormonal and behavioural mechanisms allowing animals to cope with unpredictable changes in the environment and are therefore expected to differ between populations at expansion edge and the historic range. However, to date, very few studies have evaluated the relationship between GCs and range expansion. The Egyptian mongoose has been rapidly expanding its range in Portugal over the past 30 years. In this study, we applied an information theoretic approach to determine the most important spatial and environmental predictors of hair GCs (hGCs) in the population, after controlling for normal patterns of hGC variation in the species. We observed a decrease in hGC as distance from the historic range increased (i.e. closer to the expansion front). This distance term was present in all of the top models and had a 95% confidence interval (95% CI) that did not overlap with zero, strongly supporting its influence on hGC. We estimated a 0.031 pg/mg (95% CI: -0.057, -0.004) decrease in hGCs for each kilometre distance to the Tagus River, which was once the limit of the species' distribution. Our results indicate that the species' expansion is unlikely to be limited by mechanisms related to or mediated by the physiological stress response. The decrease in hGC levels towards the expansion edge coupled with limited evidence of a negative effect of human population density suggests that the species' northward expansion in Portugal could continue.
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Affiliation(s)
- Alexandre Azevedo
- Department of Reproduction Biology, Leibniz Institute for Zoo and Wildlife Research, Berlin, Germany
- Instituto de Ciências Biomédicas Abel Salazar - University of Porto, R. Jorge de Viterbo Ferreira 228, 4050-313 Porto, Portugal
- Corresponding author: Department of Reproduction Biology, Leibniz Institute for Zoo and Wildlife Research, Alfred-Kowalke-Straße 17, 10315 Berlin, Germany.
| | - Liam Bailey
- Department of Evolutionary Genetics, Leibniz Institute for Zoo and Wildlife Research, Berlin, Germany
| | - Victor Bandeira
- Department of Biology and CESAM, University of Aveiro, Campus Universitário de Santiago, 3810-193 Aveiro, Portugal
| | - Carlos Fonseca
- Department of Biology and CESAM, University of Aveiro, Campus Universitário de Santiago, 3810-193 Aveiro, Portugal
- ForestWISE - Collaborative Laboratory for Integrated Forest and Fire Management, Quinta de Prados, Campus da UTAD 5001-801 Vila Real, Portugal
| | - Jella Wauters
- Department of Reproduction Biology, Leibniz Institute for Zoo and Wildlife Research, Berlin, Germany
| | - Katarina Jewgenow
- Department of Reproduction Biology, Leibniz Institute for Zoo and Wildlife Research, Berlin, Germany
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7
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Gardner ST, Kepas M, Simons CR, Horne LM, Savitzky AH, Mendonça MT. Differences in morphology and in composition and release of parotoid gland secretion in introduced cane toads ( Rhinella marina) from established populations in Florida, USA. Ecol Evol 2021; 11:1013-1022. [PMID: 33520183 PMCID: PMC7820141 DOI: 10.1002/ece3.7118] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2020] [Revised: 11/08/2020] [Accepted: 11/13/2020] [Indexed: 11/17/2022] Open
Abstract
Cane toads are highly toxic bufonids invasive in several locations throughout the world. Although physiological changes and effects on native predators for Australian populations have been well documented, Florida populations have received little attention. Cane toads were collected from populations spanning the invaded range in Florida to assess relative toxicity, through measuring morphological changes to parotoid glands, likelihood of secretion, and the marinobufagenin (MBG) content of secretion. We found that residual body indices increased in individuals from higher latitude populations, and relative parotoid gland size increased with increasing toad size. There was no effect of latitude on the allometric relationship between gland size and toad size. We observed an increase in likelihood of secretion by cane toads in the field with increasing latitude. Individuals from southern and northern populations did not vary significantly in the quantity of MBG contained in their secretion. Laboratory-acclimated cane toads receiving injections of epinephrine were more likely to secrete poison with increasing dose, although there was no difference in likelihood of secretion between southern and northern populations. This suggests that differences between populations in the quantities of epinephrine released in the field, due to altered hypothalamic sensitivity upon disturbance, may be responsible for the latitudinal effects on poison secretion. Our results suggest that altered pressures from northward establishment in Florida have affected sympathetic sensitivity and defensive mechanisms of cane toads, potentially affecting risk to native predators.
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Affiliation(s)
| | - Megen Kepas
- Department of BiologyUtah State UniversityLoganUtahUSA
| | - Casey R. Simons
- Department of Chemistry and BiochemistryUtah State UniversityLoganUtahUSA
| | - Logan M. Horne
- Department of Biological SciencesUniversity of Texas at El PasoEl PasoTexasUSA
| | | | - Mary T. Mendonça
- Department of Biological SciencesAuburn UniversityAuburnAlabamaUSA
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8
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Laid-back invaders: Cane toads (Rhinella marina) down-regulate their stress responses as they colonize a harsh climate. Glob Ecol Conserv 2020. [DOI: 10.1016/j.gecco.2020.e01248] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
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9
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Iglesias-Carrasco M, Aich U, Jennions MD, Head ML. Stress in the city: meta-analysis indicates no overall evidence for stress in urban vertebrates. Proc Biol Sci 2020; 287:20201754. [PMID: 33023414 PMCID: PMC7657868 DOI: 10.1098/rspb.2020.1754] [Citation(s) in RCA: 26] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2020] [Accepted: 09/14/2020] [Indexed: 12/12/2022] Open
Abstract
As cities continue to grow it is increasingly important to understand the long-term responses of wildlife to urban environments. There have been increased efforts to determine whether urbanization imposes chronic stress on wild animals, but empirical evidence is mixed. Here, we conduct a meta-analysis to test whether there is, on average, a detrimental effect of urbanization based on baseline and stress-induced glucocorticoid levels of wild vertebrates. We found no effect of urbanization on glucocorticoid levels, and none of sex, season, life stage, taxon, size of the city nor methodology accounted for variation in the observed effect sizes. At face value, our results suggest that urban areas are no more stressful for wildlife than rural or non-urban areas, but we offer a few reasons why this conclusion could be premature. We propose that refining methods of data collection will improve our understanding of how urbanization affects the health and survival of wildlife.
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Affiliation(s)
- Maider Iglesias-Carrasco
- Division of Evolution, Ecology and Genetics, Research School of Biology, Australian National University, Canberra, Australian Capital Territory, Australia
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10
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Assis VR, Gardner ST, Smith KM, Gomes FR, Mendonça MT. Stress and immunity: Field comparisons among populations of invasive cane toads in Florida. JOURNAL OF EXPERIMENTAL ZOOLOGY PART 2020; 333:779-791. [PMID: 32488987 DOI: 10.1002/jez.2389] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/27/2020] [Revised: 05/07/2020] [Accepted: 05/22/2020] [Indexed: 12/28/2022]
Abstract
Cane toads (Rhinella marina) were introduced worldwide and have become invasive in multiple locations, representing a major driver of biodiversity loss through competition (food, shelter, territory), predation, and the poisoning of native species. These toads have been used in Australia as a model for studies concerning invasion biology and ecoimmunology, as longer-established (core) and invasion front (edge) populations show altered stress and immune response profiles. Although cane toads were also introduced into the United States in the 1950s, these patterns have yet to be evaluated for the populations spanning Florida. Toads introduced into Florida have dispersed primarily northward along a latitudinal gradient, where they encounter cooler temperatures that may further impact stress and immune differences between core and edge populations. In this study, we sampled cane toads from nine different locations spanning their invasion in Florida. Cane toads from southern populations showed higher plasma bacterial killing ability and natural antibody titers than the toads from the northern populations, indicating they have a better immune surveillance system. Also, southern toads were more responsive to a novel stressor (1 hr restraint), showing a higher increase in corticosterone levels. These results indicate that possible trade-offs have occurred between immune and stress responses as these toads have become established in northern cooler areas in Florida.
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Affiliation(s)
- Vania R Assis
- Departamento de Fisiologia, Instituto de Biociências, Universidade de São Paulo, São Paulo, SP, Brazil
| | - Steven T Gardner
- Department of Biological Sciences, Auburn University, Auburn, Alabama
| | - Kyra M Smith
- Department of Biological Sciences, Auburn University, Auburn, Alabama
| | - Fernando R Gomes
- Departamento de Fisiologia, Instituto de Biociências, Universidade de São Paulo, São Paulo, SP, Brazil
| | - Mary T Mendonça
- Department of Biological Sciences, Auburn University, Auburn, Alabama
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11
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Becker DJ, Downs CJ, Martin LB. Multi-Scale Drivers of Immunological Variation and Consequences for Infectious Disease Dynamics. Integr Comp Biol 2020; 59:1129-1137. [PMID: 31559436 DOI: 10.1093/icb/icz138] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
The immune system is the primary barrier to parasite infection, replication, and transmission following exposure, and variation in immunity can accordingly manifest in heterogeneity in traits that govern population-level infectious disease dynamics. While much work in ecoimmunology has focused on individual-level determinants of host immune defense (e.g., reproductive status and body condition), an ongoing challenge remains to understand the broader evolutionary and ecological contexts of this variation (e.g., phylogenetic relatedness and landscape heterogeneity) and to connect these differences into epidemiological frameworks. Ultimately, such efforts could illuminate general principles about the drivers of host defense and improve predictions and control of infectious disease. Here, we highlight recent work that synthesizes the complex drivers of immunological variation across biological scales of organization and scales these within-host differences to population-level infection outcomes. Such studies note the limitations involved in making species-level comparisons of immune phenotypes, stress the importance of spatial scale for immunology research, showcase several statistical tools for translating within-host data into epidemiological parameters, and provide theoretical frameworks for linking within- and between-host scales of infection processes. Building from these studies, we highlight several promising avenues for continued work, including the application of machine learning tools and phylogenetically controlled meta-analyses to immunology data and quantifying the joint spatial and temporal dependencies in immune defense using range expansions as model systems. We also emphasize the use of organismal traits (e.g., host tolerance, competence, and resistance) as a way to interlink various scales of analysis. Such continued collaboration and disciplinary cross-talk among ecoimmunology, disease ecology, and mathematical modeling will facilitate an improved understanding of the multi-scale drivers and consequences of variation in host defense.
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Affiliation(s)
- Daniel J Becker
- Department of Biology, Indiana University, Bloomington, IN 47405, USA.,Center for the Ecology of Infectious Disease, University of Georgia, Athens, GA 30602, USA
| | - Cynthia J Downs
- Department of Biology, Hamilton College, Clinton, NY 13323, USA
| | - Lynn B Martin
- Department of Global and Planetary Health, University of South Florida, Tampa, FL 33620, USA
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12
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Effects of stress-induced increases of corticosterone on circulating triglyceride levels, biliverdin concentration, and heme oxygenase expression. Comp Biochem Physiol A Mol Integr Physiol 2020; 240:110608. [DOI: 10.1016/j.cbpa.2019.110608] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2019] [Revised: 10/30/2019] [Accepted: 10/30/2019] [Indexed: 12/13/2022]
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13
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Kilvitis HJ, Ardia DR, Thiam M, Martin LB. Corticosterone is correlated to mediators of neural plasticity and epigenetic potential in the hippocampus of Senegalese house sparrows (Passer domesticus). Gen Comp Endocrinol 2018; 269:177-183. [PMID: 30257180 DOI: 10.1016/j.ygcen.2018.09.014] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/13/2018] [Revised: 09/19/2018] [Accepted: 09/21/2018] [Indexed: 10/28/2022]
Abstract
Our previous research on range-expanding house sparrows in Kenya revealed that (i) range-edge birds released more corticosterone (CORT) in response to a stressor than range-core birds, ii) that range-edge birds were more exploratory than range-core birds, and that (iii) all birds exhibited extensive variation in genome-wide DNA methylation among individuals, regardless of their position along the range expansion. Within the hippocampus, mediators of neural plasticity such as brain-derived neurotrophic factor (BDNF), can influence and be influenced by CORT, hippocampus-associated behaviors and regulatory epigenetic modification enzymes. Here, we investigated whether individuals and populations colonizing a new geographic range, Senegal, vary in the expression of BDNF and DNA methyltransferases (DNMTs) within the hippocampus and the release of CORT in response to a stressor. DNMT expression is an important mediator of epigenetic potential, the propensity of a genome to capacitate phenotypic variation via mechanisms such as DNA methylation. We surveyed three populations across Senegal, predicting that hippocampal BDNF and DNMT expression would be highest at the range-edge, and that BDNF and DNMT would be inversely related to one another, but would each positively covary with CORT within individuals. We found a nonlinear relationship between CORT and BDNF expression within individuals. Moreover, we found that CORT positively covaried with DNMT1 expression in a more recently established population, while the reverse was true in the oldest population (i.e. at the range-core). Our study is among the first to explore whether and how variation in CORT regulation contributes to variation in mediators of neural plasticity and epigenetic potential within the hippocampus of a range-expanding vertebrate.
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Affiliation(s)
- Holly J Kilvitis
- University of South Florida, Department of Integrative Biology, Tampa, FL, USA.
| | - Daniel R Ardia
- Franklin & Marshall College, Department of Biology, Lancaster, PA, USA
| | - Massamba Thiam
- Universite Cheikh Anta Diop, Department of Biology, Dakar, Senegal
| | - Lynn B Martin
- University of South Florida, Department of Global Health, Tampa, FL, USA
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14
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Garamszegi LZ, Donald J, Francis CD, Fuxjager MJ, Goymann W, Hau M, Husak JF, Johnson MA, Kircher B, Knapp R, Martin LB, Miller ET, Schoenle LA, Vitousek MN, Williams TD. Species-Specific Means and Within-Species Variance in Glucocorticoid Hormones and Speciation Rates in Birds. Integr Comp Biol 2018; 58:763-776. [PMID: 30011006 DOI: 10.1093/icb/icy086] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
At macroevolutionary scales, stress physiology may have consequences for species diversification and subspecies richness. Populations that exploit new resources or undergo range expansion should cope with new environmental challenges, which could favor higher mean stress responses. Within-species variation in the stress response may also play a role in mediating the speciation process: in species with broad variation, there will always be some individuals that can tolerate an unpredictable environment, whereas in species with narrow variation there will be fewer individuals that are able to thrive in a new ecological niche. We tested for the evolutionary relationship between stress response, speciation rate, and subspecies richness in birds by relying on the HormoneBase repository, from which we calculated within- and among-species variation in baseline (BL) and stress-induced (SI) corticosterone levels. To estimate speciation rates, we applied Bayesian analysis of macroevolutionary mixtures that can account for variation in diversification rate among clades and through time. Contrary to our predictions, lineages with higher diversification rates were not characterized by higher BL or SI levels of corticosterone either at the tips or at the deeper nodes of the phylogeny. We also found no association between mean hormone levels and subspecies richness. Within-species variance in corticosterone levels showed close to zero repeatability, thus it is highly unlikely that this is a species-specific trait that influences diversification rates. These results imply that stress physiology may play a minor, if any, role in determining speciation rates in birds.
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Affiliation(s)
- László Zsolt Garamszegi
- Department of Evolutionary Ecology, Estación Biológica de Doñana-CSIC, c/Americo Vespucio, 26, 41092 Seville, Spain.,MTA-ELTE Theoretical Biology and Evolutionary Ecology Research Group, Department of Plant Systematics, Ecology and Theoretical Biology, Eötvös Loránd University, Budapest H-1117, Hungary
| | - Jeremy Donald
- Coates Library, Trinity University, San Antonio, TX 78212, USA
| | - Clinton D Francis
- Biological Sciences Department, California Polytechnic State University, San Luis Obispo, CA 93407, USA
| | - Matthew J Fuxjager
- Department of Biology, Wake Forest University, Winston-Salem, NC 27109, USA
| | | | - Michaela Hau
- Max Planck Institute for Ornithology, Seewiesen 82319, Germany.,University of Konstanz, Konstanz 78464, Germany
| | - Jerry F Husak
- Department of Biology, University of St. Thomas, St. Paul, MN 55105, USA
| | - Michele A Johnson
- Department of Biology, Trinity University, San Antonio, TX 78212, USA
| | - Bonnie Kircher
- Department of Biology, University of Florida, Gainesville, FL 32608, USA
| | - Rosemary Knapp
- Department of Biology, University of Oklahoma, Norman, OK 73019, USA
| | - Lynn B Martin
- Department of Global Health, University of South Florida, Tampa, FL 33620, USA
| | | | - Laura A Schoenle
- Department of Biological Sciences, Virginia Tech, Blacksburg, VA 24061, USA
| | - Maren N Vitousek
- Cornell Lab of Ornithology, Ithaca, NY 14850, USA.,Department of Ecology and Evolutionary Biology, Cornell University, Ithaca, NY 14853, USA
| | - Tony D Williams
- Department of Biological Sciences, Simon Fraser University, Burnaby, British Columbia, V5A 1S6, Canada
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Kilvitis HJ, Hanson H, Schrey AW, Martin LB. Epigenetic Potential as a Mechanism of Phenotypic Plasticity in Vertebrate Range Expansions. Integr Comp Biol 2018; 57:385-395. [PMID: 28859411 DOI: 10.1093/icb/icx082] [Citation(s) in RCA: 37] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
SYNOPSIS During range expansions, organisms are often exposed to multiple pressures, including novel enemies (i.e., predators, competitors and/or parasites) and unfamiliar or limited resources. Additionally, small propagule sizes at range edges can result in genetic founder effects and bottlenecks, which can affect phenotypic diversity and thus selection. Despite these obstacles, individuals in expanding populations often thrive at the periphery of a range, and this success may be mediated by phenotypic plasticity. Increasing evidence suggests that epigenetic mechanisms may underlie such plasticity because they allow for more rapid phenotypic responses to novel environments than are possible via the accumulation of genetic variation. Here, we review how molecular epigenetic mechanisms could facilitate plasticity in range-expanding organisms, emphasizing the roles of DNA methylation and other epigenetic marks in the physiological regulatory networks that drive whole-organism performance. We focus on the hypothalamic-pituitary-adrenal (HPA) axis, arguing that epigenetically-mediated plasticity in the regulation of glucocorticoids in particular might strongly impact range expansions. We hypothesize that novel environments release and/or select for epigenetic potential in HPA variation and hence organismal performance and ultimately fitness.
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Affiliation(s)
- Holly J Kilvitis
- Department of Integrative Biology, University of South Florida, Tampa, FL 33620, USA
| | - Haley Hanson
- Department of Integrative Biology, University of South Florida, Tampa, FL 33620, USA
| | - Aaron W Schrey
- Department of Biology, Armstrong State University, Savannah, GA 31419, USA
| | - Lynn B Martin
- Department of Integrative Biology, University of South Florida, Tampa, FL 33620, USA
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