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Lazzaro BP, Tate AT. Balancing sensitivity, risk, and immunopathology in immune regulation. CURRENT OPINION IN INSECT SCIENCE 2022; 50:100874. [PMID: 35051619 PMCID: PMC9133098 DOI: 10.1016/j.cois.2022.100874] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/05/2021] [Revised: 12/23/2021] [Accepted: 01/11/2022] [Indexed: 06/14/2023]
Abstract
Activation of an immune response is energetically costly and excessive immune system activity can result in immunopathology, yet a slow or insufficient immune response carries the risk of pathogen establishment with consequent pathology arising from the infection. Mathematical theory and empirical data demonstrate that hosts balance the costs of immunity against the risk of infection by closely regulating immunological dynamics. An optimal immune system is rapidly and robustly deployed against a true infectious threat and rapidly deactivated once the threat has been controlled. Genetic variation in the sensitivity of an immune system, as well as in the activation and shutdown kinetics of host immune responses, can contribute to the evolution of pathogen virulence and host tolerance of infection. Improved understanding of the adaptive forces that operate on immune regulatory dynamics will clarify fundamental principles governing the evolution and maintenance of innate immune systems.
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Affiliation(s)
- Brian P Lazzaro
- Departments of Entomology and Ecology & Evolutionary Biology, Cornell Institute of Host-Microbe Interactions and Disease, Cornell University, Ithaca, NY, USA.
| | - Ann T Tate
- Department of Biological Sciences, Vanderbilt University, Nashville, TN, USA
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2
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Neff E, Evans CC, Jimenez Castro PD, Kaplan RM, Dharmarajan G. Drug Resistance in Filarial Parasites Does Not Affect Mosquito Vectorial Capacity. Pathogens 2020; 10:2. [PMID: 33375024 PMCID: PMC7822010 DOI: 10.3390/pathogens10010002] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2020] [Revised: 12/15/2020] [Accepted: 12/18/2020] [Indexed: 12/19/2022] Open
Abstract
Parasite drug resistance presents a major obstacle to controlling and eliminating vector-borne diseases affecting humans and animals. While vector-borne disease dynamics are affected by factors related to parasite, vertebrate host and vector, research on drug resistance in filarial parasites has primarily focused on the parasite and vertebrate host, rather than the mosquito. However, we expect that the physiological costs associated with drug resistance would reduce the fitness of drug-resistant vs. drug-susceptible parasites in the mosquito wherein parasites are not exposed to drugs. Here we test this hypothesis using four isolates of the dog heartworm (Dirofilaria immitis)-two drug susceptible and two drug resistant-and two vectors-the yellow fever mosquito (Aedes aegypti) and the Asian tiger mosquito (Ae. albopictus)-as our model system. Our data indicated that while vector species had a significant effect on vectorial capacity, there was no significant difference in the vectorial capacity of mosquitoes infected with drug-resistant vs. drug-susceptible parasites. Consequently, contrary to expectations, our data indicate that drug resistance in D. immitis does not appear to reduce the transmission efficiency of these parasites, and thus the spread of drug-resistant parasites in the vertebrate population is unlikely to be mitigated by reduced fitness in the mosquito vector.
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Affiliation(s)
- Erik Neff
- Savannah River Ecology Laboratory, University of Georgia, Drawer E, Aiken, SC 29802, USA
| | - Christopher C. Evans
- Department of Infectious Diseases, College of Veterinary Medicine, University of Georgia, Athens, GA 30602, USA; (C.C.E.); (P.D.J.C.); (R.M.K.)
| | - Pablo D. Jimenez Castro
- Department of Infectious Diseases, College of Veterinary Medicine, University of Georgia, Athens, GA 30602, USA; (C.C.E.); (P.D.J.C.); (R.M.K.)
- Grupo de Parasitología Veterinaria, Universidad Nacional de Colombia, Bogotá 11001000, Colombia
| | - Ray M. Kaplan
- Department of Infectious Diseases, College of Veterinary Medicine, University of Georgia, Athens, GA 30602, USA; (C.C.E.); (P.D.J.C.); (R.M.K.)
| | - Guha Dharmarajan
- Savannah River Ecology Laboratory, University of Georgia, Drawer E, Aiken, SC 29802, USA
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3
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Support for the Transmission-Clearance Trade-Off Hypothesis from a Study of Zika Virus Delivered by Mosquito Bite to Mice. Viruses 2019; 11:v11111072. [PMID: 31752097 PMCID: PMC6893444 DOI: 10.3390/v11111072] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2019] [Revised: 11/04/2019] [Accepted: 11/14/2019] [Indexed: 02/07/2023] Open
Abstract
Evolutionary theory indicates that virus virulence is shaped by a trade-off between instantaneous rate of transmission and duration of infection. For most viruses, infection is curtailed by immune clearance, but there are few empirical tests of the transmission–clearance trade-off hypothesis. We exposed A129 mice to bites from groups of 1, 2–4, or 6–9 Aedes albopictus mosquitoes infected with Zika virus (ZIKV). We predicted that a higher number of infectious mosquito bites would deliver a higher total dose of the virus, and that increasing dose would result in earlier onset, higher magnitude, and shorter duration of viremia, as well as a more robust neutralizing antibody response. We found that increases in the number of mosquito bites delivered resulted in significantly different virus replication dynamics with higher, earlier peak titers. All mice experienced a transient weight loss following infection, but the nadir in weight loss was delayed in the mice that received the highest number of bites. Viremia persisted past the period of measurement in this study, so we did not capture its duration. However, the association at the level of the individual mouse between the estimated virus dose delivered and neutralizing antibody titer was remarkably strong, supporting the transmission–clearance trade-off hypothesis.
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Host circadian rhythms are disrupted during malaria infection in parasite genotype-specific manners. Sci Rep 2019; 9:10905. [PMID: 31358780 PMCID: PMC6662749 DOI: 10.1038/s41598-019-47191-8] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2018] [Accepted: 07/11/2019] [Indexed: 12/19/2022] Open
Abstract
Infection can dramatically alter behavioural and physiological traits as hosts become sick and subsequently return to health. Such “sickness behaviours” include disrupted circadian rhythms in both locomotor activity and body temperature. Host sickness behaviours vary in pathogen species-specific manners but the influence of pathogen intraspecific variation is rarely studied. We examine how infection with the murine malaria parasite, Plasmodium chabaudi, shapes sickness in terms of parasite genotype-specific effects on host circadian rhythms. We reveal that circadian rhythms in host locomotor activity patterns and body temperature become differentially disrupted and in parasite genotype-specific manners. Locomotor activity and body temperature in combination provide more sensitive measures of health than commonly used virulence metrics for malaria (e.g. anaemia). Moreover, patterns of host disruption cannot be explained simply by variation in replication rate across parasite genotypes or the severity of anaemia each parasite genotype causes. It is well known that disruption to circadian rhythms is associated with non-infectious diseases, including cancer, type 2 diabetes, and obesity. Our results reveal that disruption of host circadian rhythms is a genetically variable virulence trait of pathogens with implications for host health and disease tolerance.
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Pike VL, Lythgoe KA, King KC. On the diverse and opposing effects of nutrition on pathogen virulence. Proc Biol Sci 2019; 286:20191220. [PMID: 31288706 PMCID: PMC6650706 DOI: 10.1098/rspb.2019.1220] [Citation(s) in RCA: 26] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2019] [Accepted: 06/17/2019] [Indexed: 01/01/2023] Open
Abstract
Climate change and anthropogenic activity are currently driving large changes in nutritional availability across ecosystems, with consequences for infectious disease. An increase in host nutrition could lead to more resources for hosts to expend on the immune system or for pathogens to exploit. In this paper, we report a meta-analysis of studies on host-pathogen systems across the tree of life, to examine the impact of host nutritional quality and quantity on pathogen virulence. We did not find broad support across studies for a one-way effect of nutrient availability on pathogen virulence. We thus discuss a hypothesis that there is a balance between the effect of host nutrition on the immune system and on pathogen resources, with the pivot point of the balance differing for vertebrate and invertebrate hosts. Our results suggest that variation in nutrition, caused by natural or anthropogenic factors, can have diverse effects on infectious disease outcomes across species.
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Affiliation(s)
| | | | - Kayla C. King
- Department of Zoology, University of Oxford, Oxford OX1 3SZ, UK
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Kamiya T, Mideo N, Alizon S. Coevolution of virulence and immunosuppression in multiple infections. J Evol Biol 2018; 31:995-1005. [DOI: 10.1111/jeb.13280] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2017] [Revised: 03/19/2018] [Accepted: 03/29/2018] [Indexed: 12/22/2022]
Affiliation(s)
- Tsukushi Kamiya
- Department of Ecology & Evolutionary Biology; University of Toronto; Toronto ON Canada
| | - Nicole Mideo
- Department of Ecology & Evolutionary Biology; University of Toronto; Toronto ON Canada
| | - Samuel Alizon
- Laboratoire MIVEGEC (UMR CNRS 5290, UR IRD 224, UM); Montpellier France
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Babayan SA, Liu W, Hamilton G, Kilbride E, Rynkiewicz EC, Clerc M, Pedersen AB. The Immune and Non-Immune Pathways That Drive Chronic Gastrointestinal Helminth Burdens in the Wild. Front Immunol 2018; 9:56. [PMID: 29459856 PMCID: PMC5807686 DOI: 10.3389/fimmu.2018.00056] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2017] [Accepted: 01/09/2018] [Indexed: 01/09/2023] Open
Abstract
Parasitic helminths are extremely resilient in their ability to maintain chronic infection burdens despite (or maybe because of) their hosts’ immune response. Explaining how parasites maintain these lifelong infections, identifying the protective immune mechanisms that regulate helminth infection burdens, and designing prophylactics and therapeutics that combat helminth infection, while preserving host health requires a far better understanding of how the immune system functions in natural habitats than we have at present. It is, therefore, necessary to complement mechanistic laboratory-based studies with studies on wild populations and their natural parasite communities. Unfortunately, the relative paucity of immunological tools for non-model species has held these types of studies back. Thankfully, recent progress in high-throughput ‘omics platforms provide powerful and increasingly practical means for immunologists to move beyond traditional lab-based model organisms. Yet, assigning both metabolic and immune function to genes, transcripts, and proteins in novel species and assessing how they interact with other physiological and environmental factors requires identifying quantitative relationships between their expression and infection. Here, we used supervised machine learning to identify gene networks robustly associated with burdens of the gastrointestinal nematode Heligmosomoides polygyrus in its natural host, the wild wood mice Apodemus sylvaticus. Across 34 mice spanning two wild populations and across two different seasons, we found 17,639 transcripts that clustered in 131 weighted gene networks. These clusters robustly predicted H. polygyrus burden and included well-known effector and regulatory immune genes, but also revealed a number of genes associated with the maintenance of tissue homeostasis and hematopoiesis that have so far received little attention. We then tested the effect of experimentally reducing helminth burdens through drug treatment on those putatively protective immune factors. Despite the near elimination of H. polygyrus worms, the treatment had surprisingly little effect on gene expression. Taken together, these results suggest that hosts balance tissue homeostasis and protective immunity, resulting in relatively stable immune and, consequently, parasitological profiles. In the future, applying our approach to larger numbers of samples from additional populations will help further increase our ability to detect the immune pathways that determine chronic gastrointestinal helminth burdens in the wild.
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Affiliation(s)
- Simon A Babayan
- Institute of Biodiversity, Animal Health & Comparative Medicine, University of Glasgow, Glasgow, United Kingdom
| | - Wei Liu
- Institute of Biodiversity, Animal Health & Comparative Medicine, University of Glasgow, Glasgow, United Kingdom
| | | | - Elizabeth Kilbride
- Institute of Biodiversity, Animal Health & Comparative Medicine, University of Glasgow, Glasgow, United Kingdom
| | - Evelyn C Rynkiewicz
- Institute of Evolutionary Biology and Centre for Immunity, Infection and Evolution, School of Biological Sciences, University of Edinburgh, Edinburgh, United Kingdom
| | - Melanie Clerc
- Institute of Evolutionary Biology and Centre for Immunity, Infection and Evolution, School of Biological Sciences, University of Edinburgh, Edinburgh, United Kingdom
| | - Amy B Pedersen
- Institute of Evolutionary Biology and Centre for Immunity, Infection and Evolution, School of Biological Sciences, University of Edinburgh, Edinburgh, United Kingdom
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Demographically framing trade-offs between sensitivity and specificity illuminates selection on immunity. Nat Ecol Evol 2017; 1:1766-1772. [PMID: 28963489 DOI: 10.1038/s41559-017-0315-3] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2017] [Accepted: 07/26/2017] [Indexed: 12/14/2022]
Abstract
A fundamental challenge faced by the immune system is to discriminate contexts meriting activation from contexts in which activation would be harmful. Selection pressures on this ability are likely to be acute: the penalty of mis-identification of pathogens (therefore failure to attack them) is mortality or morbidity linked to infectious disease, which could reduce fitness by reducing lifespan or fertility; the penalty associated with mis-identification of host (therefore self-attack) is immunopathology, whose fitness costs can also be extreme. Here we use classic epidemiological tools to frame this trade-off between sensitivity and specificity of immune activation, exploring implications for evolution of immune discrimination. We capture the expected increase in the evolutionarily optimal sensitivity under higher pathogen mortality risk, and a decrease in sensitivity with increased immunopathology mortality risk; but a number of non-intuitive predictions also emerge. All else being equal, optimal sensitivity decreases with increasing lifespan; and, where sensitivity can vary over age, decreases at late ages not solely attributable to immunosenescence are predicted. These results both enrich and challenge previous predictions concerning the relationship between life expectancy and optimal evolved defenses, highlighting the need to account for epidemiological setting, lifestage-specific immune priorities, and immune discrimination in future investigations.
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Sorci G, Lippens C, Léchenault C, Faivre B. Benefits of immune protection versus immunopathology costs: A synthesis from cytokine KO models. INFECTION GENETICS AND EVOLUTION 2017; 54:491-495. [PMID: 28818622 DOI: 10.1016/j.meegid.2017.08.014] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/23/2017] [Revised: 07/19/2017] [Accepted: 08/14/2017] [Indexed: 12/24/2022]
Abstract
The inflammatory response can produce damage to host tissues and in several infectious diseases the most severe symptoms are due to immunopathology rather than a direct effect of pathogen multiplication. One hypothesis for the persistence of inflammatory damage posits that the benefits of protection towards infection outweigh the costs. We used data on knocked-out (KO) cytokine models [and the corresponding wild-type (WT) controls] to test this hypothesis. We computed differences in pathogen load and host survival between WT and KO and divided them by the WT values. Using this ratio provides an internal control for variation in pathogen species, host strain, pathogen dose, and inoculation route. We predicted that i) if mortality is essentially due to immunopathology, there should be a loose association between pathogen load and host survival; ii) if mortality is essentially due to pathogen proliferation, we expect a tight association between pathogen load and host survival. The results provide strong support to this latter hypothesis. In 85% of WT - KO comparisons (n=126), an increase in pathogen load was associated with an increase in host mortality, and a decrease in pathogen load was associated with a decrease in host mortality. Overall, these findings are in agreement with the idea that immunopathology persists because immune protection confers immediate benefits in terms of infection clearance.
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Affiliation(s)
- Gabriele Sorci
- Biogéosciences, CNRS UMR 6282, Université de Bourgogne Franche-Comté, 6 boulevard Gabriel, 21000 Dijon, France.
| | - Cédric Lippens
- Biogéosciences, CNRS UMR 6282, Université de Bourgogne Franche-Comté, 6 boulevard Gabriel, 21000 Dijon, France
| | - Clothilde Léchenault
- Biogéosciences, CNRS UMR 6282, Université de Bourgogne Franche-Comté, 6 boulevard Gabriel, 21000 Dijon, France
| | - Bruno Faivre
- Biogéosciences, CNRS UMR 6282, Université de Bourgogne Franche-Comté, 6 boulevard Gabriel, 21000 Dijon, France
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Martin LB, Kilvitis HJ, Brace AJ, Cooper L, Haussmann MF, Mutati A, Fasanello V, O'Brien S, Ardia DR. Costs of immunity and their role in the range expansion of the house sparrow in Kenya. J Exp Biol 2017; 220:2228-2235. [DOI: 10.1242/jeb.154716] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2016] [Accepted: 04/02/2017] [Indexed: 01/09/2023]
Abstract
There are at least two reasons to study traits that mediate successful range expansions. First, dispersers will found new populations and thus impact the distribution and evolution of species. Second, organisms moving into new areas will influence the fate of resident communities, directly competing with or indirectly affecting residents by spreading non-native or spilling-back native parasites. The success of invaders in new areas is likely mediated by a counterbalancing of costly traits. In new areas where threats are comparatively rare, individuals that grow rapidly and breed prolifically should be at an advantage. High investment in defenses should thus be disfavored. In the present study, we compared the energetic, nutritional and collateral damage costs of an inflammatory response among Kenyan house sparrow (Passer domesticus) populations of different ages, asking whether costs were related to traits of individuals from three different capture sites. Kenya is among the world's most recent range expansions for this species, and we recently found that the expression of Toll-like receptors (TLRs), leukocyte receptors that instigate inflammatory responses when bound to microbial elements, was related to the range expansion across the country. Here, we found (contrary to our expectations) that energetic and nutritional costs of inflammation were higher, but damage costs were lower, in range-edge compared to core birds. Moreover, at the individual level, TLR-4 expression was negatively related to commodity costs (energy and a critical amino acid) of inflammation. Our data thus suggest that costs of inflammation, perhaps mediated by TLR expression, might mitigate successful range expansions.
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Affiliation(s)
- Lynn B. Martin
- University of South Florida, Department of Integrative Biology, Tampa FL 33620, USA
| | - Holly J. Kilvitis
- University of South Florida, Department of Integrative Biology, Tampa FL 33620, USA
| | - Amber J. Brace
- University of South Florida, Department of Integrative Biology, Tampa FL 33620, USA
| | - Laken Cooper
- Radford University, Department of Biology, Radford, VA 24142, USA
| | | | - Alex Mutati
- National Museums of Kenya, Department of Ornithology, Nairobi, Kenya
| | - Vincent Fasanello
- Bucknell University, Department of Biology, Lewisburg, PA, USA
- Washington University in Saint Louis, Department of Biology, Saint Louis, MO, USA
| | - Sara O'Brien
- Radford University, Department of Biology, Radford, VA 24142, USA
| | - Daniel R. Ardia
- Franklin and Marshall College, Department of Biology, Lancaster, PA, USA
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Mavondo GA, Mkhwananzi BN, Mabandla MV, Musabayane CT. Asiatic acid influences parasitaemia reduction and ameliorates malaria anaemia in P. berghei infected Sprague-Dawley male rats. Altern Ther Health Med 2016; 16:357. [PMID: 27618936 PMCID: PMC5020548 DOI: 10.1186/s12906-016-1338-z] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2016] [Accepted: 09/03/2016] [Indexed: 01/11/2023]
Abstract
BACKGROUND Current malaria treatment is either "anti-parasitic", "anti-infectivity" or both without addressing the pathophysiological derangement (anti-disease aspect) associated with the disease. Asiatic acid is a natural phytochemical with oxidant, antioxidant and anti-inflammatory properties whose effect on malarial and accompanying pathophysiology are yet to be investigated. Asiatic acid influence in P. berghei-infected Sprague Dawley rats on %parasitaemia and malarial anaemia were investigated. METHODS Plasmodium berghei-infected rats (90-120 g) were orally administered with Asiatic acid (5, 10, 20 mg/kg) and 30 mg/kg chloroquine as a positive control. Changes in %parasitaemia and haematological parameters in Asiatic acid administered rats were monitored in a 21 day study and compared to controls. RESULTS All animals developed stable parasitaemia (15-20 %) by day 7. Asiatic acid doses suppressed parasitaemia, normalised haematological measurements and influenced biophysical characteristics changes. Most positive changes were associated with intragastric administration of 10 mg/kg Asiatic acid dose. Peak %parasitaemia in Asiatic acid administration occurred at days 12 with a shorter time course compared to day 9 for chloroquine (30 mg/kg) treatment with a longer time course. CONCLUSIONS Oral Asiatic acid administration influenced %parasitaemia suppression, ameliorated malarial anaemia and increased biophysical properties on infected animals. Asiatic acid may be a replacement alternative for chloroquine treatment with concomitant amelioration of malaria pathophysiology. Due to different action time courses, Asiatic acid and chloroquine may be possible candidates in combination therapy.
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Martin LB, Burgan SC, Adelman JS, Gervasi SS. Host Competence: An Organismal Trait to Integrate Immunology and Epidemiology. Integr Comp Biol 2016; 56:1225-1237. [DOI: 10.1093/icb/icw064] [Citation(s) in RCA: 59] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
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Cressler CE, Graham AL, Day T. Evolution of hosts paying manifold costs of defence. Proc Biol Sci 2015; 282:20150065. [PMID: 25740895 DOI: 10.1098/rspb.2015.0065] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Abstract
Hosts are expected to incur several physiological costs in defending against parasites. These include constitutive energetic (or other resource) costs of a defence system, facultative resource costs of deploying defences when parasites strike, and immunopathological costs of collateral damage. Here, we investigate the evolution of host recovery rates, varying the source and magnitude of immune costs. In line with previous work, we find that hosts paying facultative resource costs evolve faster recovery rates than hosts paying constitutive costs. However, recovery rate is more sensitive to changes in facultative costs, potentially explaining why constitutive costs are hard to detect empirically. Moreover, we find that immunopathology costs which increase with recovery rate can erode the benefits of defence, promoting chronicity of infection. Immunopathology can also lead to hosts evolving low recovery rate in response to virulent parasites. Furthermore, when immunopathology reduces fecundity as recovery rate increases (e.g. as for T-cell responses to urogenital chlamydiosis), then recovery and reproductive rates do not covary as predicted in eco-immunology. These results suggest that immunopathological and resource costs have qualitatively different effects on host evolution and that embracing the complexity of immune costs may be essential for explaining variability in immune defence in nature.
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Affiliation(s)
- Clayton E Cressler
- Department of Mathematics and Statistics, Queen's University, Kingston, Ontario, Canada K7L 3N6
| | - Andrea L Graham
- Department of Ecology and Evolutionary Biology, Princeton University, Princeton, NJ 08544, USA
| | - Troy Day
- Department of Mathematics and Statistics, Queen's University, Kingston, Ontario, Canada K7L 3N6 Department of Biology, Queen's University, Kingston, Ontario, Canada K7L 3N6
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Abstract
Why is it that some parasites cause high levels of host damage (i.e. virulence) whereas others are relatively benign? There are now numerous reviews of virulence evolution in the literature but it is nevertheless still difficult to find a comprehensive treatment of the theory and data on the subject that is easily accessible to non-specialists. Here we attempt to do so by distilling the vast theoretical literature on the topic into a set of relatively few robust predictions. We then provide a comprehensive assessment of the available empirical literature that tests these predictions. Our results show that there have been some notable successes in integrating theory and data but also that theory and empiricism in this field do not ‘speak’ to each other very well. We offer a few suggestions for how the connection between the two might be improved.
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Abstract
Life history theory predicts that trait evolution should be constrained by competing physiological demands on an organism. Immune defense provides a classic example in which immune responses are presumed to be costly and therefore come at the expense of other traits related to fitness. One strategy for mitigating the costs of expensive traits is to render them inducible, such that the cost is paid only when the trait is utilized. In the current issue of PLOS Biology, Bajgar and colleagues elegantly demonstrate the energetic and life history cost of the immune response that Drosophila melanogaster larvae induce after infection by the parasitoid wasp Leptopilina boulardi. These authors show that infection-induced proliferation of defensive blood cells commands a diversion of dietary carbon away from somatic growth and development, with simple sugars instead being shunted to the hematopoetic organ for rapid conversion into the raw energy required for cell proliferation. This metabolic shift results in a 15% delay in the development of the infected larva and is mediated by adenosine signaling between the hematopoietic organ and the central metabolic control organ of the host fly. The adenosine signal thus allows D. melanogaster to rapidly marshal the energy needed for effective defense and to pay the cost of immunity only when infected. Fruit flies infected by a parasitoid wasp use adenosine signaling to recruit energy away from tissue growth in order to support proliferation of defensive immune cells, thereby paying a deployment cost of inducible immunity. Read the Research Article.
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Affiliation(s)
- Brian P. Lazzaro
- Department of Entomology, Cornell University, Ithaca, New York, United States of America
- * E-mail:
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Carroll S, Kinnison MT, Bernatchez L. In light of evolution: interdisciplinary challenges in food, health, and the environment. Evol Appl 2015; 4:155-8. [PMID: 25567965 PMCID: PMC3352555 DOI: 10.1111/j.1752-4571.2011.00182.x] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Affiliation(s)
- Scott Carroll
- Institute for Contemporary Evolution, Davis, CA, USA and Department of Entomology, University of California Davis, CA, USA
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17
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Belloni V, Sorci G, Paccagnini E, Guerreiro R, Bellenger J, Faivre B. Disrupting immune regulation incurs transient costs in male reproductive function. PLoS One 2014; 9:e84606. [PMID: 24400103 PMCID: PMC3882243 DOI: 10.1371/journal.pone.0084606] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2013] [Accepted: 11/15/2013] [Indexed: 11/19/2022] Open
Abstract
Background Immune protection against pathogenic organisms has been shown to incur costs. Previous studies investigating the cost of immunity have mostly focused on the metabolic requirements of immune maintenance and activation. In addition to these metabolic costs, the immune system can induce damage to the host if the immune response is mis-targeted or over-expressed. Given its non-specific nature, an over-expressed inflammatory response is often associated with substantial damage for the host. Here, we investigated the cost of an over-expressed inflammatory response in the reproductive function of male mice. Methodology/Principal Findings We experimentally blocked the receptors of an anti-inflammatory cytokine (IL-10) in male mice exposed to a mild inflammatory challenge, with each treatment having an appropriate control group. The experiment was conducted on two age classes, young (3 month old) and old (15 month old) mice, to assess any age-related difference in the cost of a disrupted immune regulation. We found that the concomitant exposure to an inflammatory insult and the blockade of IL-10 induced a reduction in testis mass, compared to the three other groups. The frequency of abnormal sperm morphology was also higher in the group of mice exposed to the inflammatory challenge but did not depend on the blockade of the IL-10. Conclusions Our results provide evidence that immune regulation confers protection against the risk of inflammation-induced infertility during infection. They also suggest that disruption of the effectors involved in the regulation of the inflammatory response can have serious fitness consequences even under mild inflammatory insult and benign environmental conditions.
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Affiliation(s)
- Virginia Belloni
- Biogéosciences, CNRS UMR 6282, Université de Bourgogne, Dijon, France
- Department Tropical Medicine, University of Tulane, New Orleans, Louisiana, United States of America
- * E-mail:
| | - Gabriele Sorci
- Biogéosciences, CNRS UMR 6282, Université de Bourgogne, Dijon, France
| | | | - Romain Guerreiro
- Biogéosciences, CNRS UMR 6282, Université de Bourgogne, Dijon, France
| | - Jérôme Bellenger
- Lipides Nutrition Cancer, INSERM UMR 866, Université de Bourgogne, Dijon, France
| | - Bruno Faivre
- Biogéosciences, CNRS UMR 6282, Université de Bourgogne, Dijon, France
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Larcombe S, Bichet C, Cornet S, Faivre B, Sorci G. Food availability and competition do not modulate the costs of Plasmodium infection in dominant male canaries. Exp Parasitol 2013; 135:708-14. [PMID: 24184773 DOI: 10.1016/j.exppara.2013.10.012] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2013] [Revised: 09/24/2013] [Accepted: 10/23/2013] [Indexed: 11/29/2022]
Abstract
Understanding the different factors that may influence parasite virulence is of fundamental interest to ecologists and evolutionary biologists. It has recently been demonstrated that parasite virulence may occur partly through manipulation of host competitive ability. Differences in competitive ability associated with the social status (dominant or subordinate) of a host may determine the extent of this competition-mediated parasite virulence. We proposed that differences between subordinate and dominant birds in the physiological costs of infection may change depending on the level of competition in social groups. We observed flocks of domestic canaries to determine dominant or subordinate birds, and modified competition by providing restricted (high competition) or ad libitum food (low competition). Entire flocks were then infected with either the avian malaria parasite, Plasmodium relictum or a control. Contrary to our predictions we found that the level of competition had no effect on the outcome of infection for dominant or subordinate birds. We found that dominant birds appeared to suffer greater infection mediated morbidity in both dietary treatments, with a higher and more sustained reduction in haematocrit, and higher parasitaemia, than subordinates. Our results show that dominance status in birds can certainly alter parasite virulence, though the links between food availability, competition, nutrition and virulence are likely to be complex and multifaceted.
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Affiliation(s)
- Stephen Larcombe
- Edward Grey Institute, Dept. of Zoology, University of Oxford, OX1 3PS, United Kingdom.
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19
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Restif O. An offer you cannot refuse: down-regulation of immunity in response to a pathogen's retaliation threat. J Evol Biol 2013; 26:2021-30. [PMID: 23927686 PMCID: PMC4274018 DOI: 10.1111/jeb.12209] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2013] [Revised: 05/16/2013] [Accepted: 05/28/2013] [Indexed: 12/15/2022]
Abstract
According to the Red Queen hypothesis, hosts and pathogens are engaged in an escalating coevolutionary arms race between resistance and virulence. However, the vast majority of symbionts colonize their hosts' mucosal compartments without triggering any immune response, resulting in durable commensal associations. Here, I propose a simple extension of previous mathematical models for antagonistic coevolution in which the host can mount a delayed immune response; in response, the symbiont can change its virulence following this activation. Even though the levels of virulence in both phases are assumed to be genetically determined, this simple form of plasticity can select for commensal associations. In particular, coevolution can result in hosts that do not activate their immune response, thus preventing phenotypically plastic pathogens from switching to a higher virulence level. I argue that, from the host's point of view, this state is analogous to the mafia behaviour previously described in avian brood parasites. More importantly, this study provides a new hypothesis for the maintenance of a commensal relationship through antagonistic coevolution.
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Affiliation(s)
- O Restif
- Disease Dynamics Unit, Department of Veterinary Medicine, University of Cambridge, Cambridge CB3 0ES, UK.
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20
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Cornet S, Bichet C, Larcombe S, Faivre B, Sorci G. Impact of host nutritional status on infection dynamics and parasite virulence in a bird-malaria system. J Anim Ecol 2013; 83:256-65. [DOI: 10.1111/1365-2656.12113] [Citation(s) in RCA: 76] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2012] [Accepted: 06/15/2013] [Indexed: 12/15/2022]
Affiliation(s)
- Stéphane Cornet
- Maladies Infectieuses et Vecteurs: Ecologie, Génétique; Evolution et Contrôle (MIVEGEC); UMR CNRS 5290-IRD 224-UM1-UM2; Montpellier France
- Centre d'Ecologie Fonctionnelle et Evolutive (CEFE); UMR CNRS 5175; Montpellier France
| | - Coraline Bichet
- Biogéosciences; UMR CNRS 6282; Université de Bourgogne; Dijon France
| | - Stephen Larcombe
- Edward Grey Institute; Department of Zoology; University of Oxford; Oxford UK
| | - Bruno Faivre
- Biogéosciences; UMR CNRS 6282; Université de Bourgogne; Dijon France
| | - Gabriele Sorci
- Biogéosciences; UMR CNRS 6282; Université de Bourgogne; Dijon France
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21
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Bichet C, Cornet S, Larcombe S, Sorci G. Experimental inhibition of nitric oxide increases Plasmodium relictum (lineage SGS1) parasitaemia. Exp Parasitol 2012; 132:417-23. [PMID: 23022523 DOI: 10.1016/j.exppara.2012.09.008] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2012] [Revised: 03/23/2012] [Accepted: 09/13/2012] [Indexed: 01/29/2023]
Abstract
Malaria is a widespread vector-borne disease infecting a wide range of terrestrial vertebrates including reptiles, birds and mammals. In addition to being one of the most deadly infectious diseases for humans, malaria is a threat to wildlife. The host immune system represents the main defence against malaria parasites. Identifying the immune effectors involved in malaria resistance has therefore become a major focus of research. However, this has mostly involved humans and animal models (rodents) and how the immune system regulates malaria progression in non-model organisms has been largely ignored. The aim of the present study was to investigate the role of nitric oxide (NO) as an immune effector contributing to the control of the acute phase of infection with the avian malaria agent Plasmodium relictum. We used experimental infections of domestic canaries in conjunction with the inhibition of the enzyme inducible nitric oxide synthase (iNOS) to assess the protective function of NO during the infection, and the physiological costs paid by the host in the absence of an effective NO response. Our results show that birds treated with the iNOS inhibitor suffered from a higher parasitaemia, but did not pay a higher cost of infection (anaemia). While these findings confirm that NO contributes to the resistance to avian malaria during the acute phase of the infection, they also suggest that parasitaemia and costs of infection can be decoupled.
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Affiliation(s)
- Coraline Bichet
- BioGéosciences, UMR CNRS 5561, Université de Bourgogne, 6 Boulevard Gabriel, 21000 Dijon, France.
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22
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Metcalf CJE, Long GH, Mideo N, Forester JD, Bjørnstad ON, Graham AL. Revealing mechanisms underlying variation in malaria virulence: effective propagation and host control of uninfected red blood cell supply. J R Soc Interface 2012; 9:2804-13. [PMID: 22718989 PMCID: PMC3479917 DOI: 10.1098/rsif.2012.0340] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023] Open
Abstract
Malaria parasite clones with the highest transmission rates to mosquitoes also tend to induce the most severe fitness consequences (or virulence) in mammals. This is in accord with expectations from the virulence–transmission trade-off hypothesis. However, the mechanisms underlying how different clones cause virulence are not well understood. Here, using data from eight murine malaria clones, we apply recently developed statistical methods to infer differences in clone characteristics, including induction of differing host-mediated changes in red blood cell (RBC) supply. Our results indicate that the within-host mechanisms underlying similar levels of virulence are variable and that killing of uninfected RBCs by immune effectors and/or retention of RBCs in the spleen may ultimately reduce virulence. Furthermore, the correlation between clone virulence and the degree of host-induced mortality of uninfected RBCs indicates that hosts increasingly restrict their RBC supply with increasing intrinsic virulence of the clone with which they are infected. Our results demonstrate a role for self-harm in self-defence for hosts and highlight the diversity and modes of virulence of malaria.
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Affiliation(s)
- C J E Metcalf
- Department of Zoology, Oxford University, Oxford, UK.
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23
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Mideo N, Savill NJ, Chadwick W, Schneider P, Read AF, Day T, Reece SE. Causes of variation in malaria infection dynamics: insights from theory and data. Am Nat 2011; 178:E174-E188. [PMID: 22089879 PMCID: PMC3937740 DOI: 10.1086/662670] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
Parasite strategies for exploiting host resources are key determinants of disease severity (i.e., virulence) and infectiousness (i.e., transmission between hosts). By iterating the development of theory and empirical tests, we investigated whether variation in parasite traits across two genetically distinct clones of the rodent malaria parasite, Plasmodium chabaudi, explains differences in within-host infection dynamics and virulence. First, we experimentally tested key predictions of our earlier modeling work. As predicted, the more virulent genotype produced more progeny parasites per infected cell (burst size), but in contrast to predictions, invasion rates of red blood cells (RBCs) did not differ between the genotypes studied. Second, we further developed theory by confronting our earlier model with these new data, testing a new set of models that incorporate more biological realism, and developing novel theoretical tools for identifying differences between parasite genotypes. Overall, we found robust evidence that differences in burst sizes contribute to variation in dynamics and that differential interactions between parasites and host immune responses also play a role. In contrast to previous work, our model predicts that RBC age structure is not important for explaining dynamics. Integrating theory and empirical tests is a potentially powerful way of progressing understanding of disease biology.
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Affiliation(s)
- Nicole Mideo
- Centre for Immunity, Infection and Evolution, School of Biological Sciences, University of Edinburgh, Edinburgh EH9 3JT, United Kingdom
| | - Nicholas J. Savill
- Centre for Immunity, Infection and Evolution, School of Biological Sciences, University of Edinburgh, Edinburgh EH9 3JT, United Kingdom
- Institute of Immunity and Infection Research, School of Biological Sciences, University of Edinburgh, Edinburgh EH9 3JT, United Kingdom
| | - William Chadwick
- Institute of Evolutionary Biology, School of Biological Sciences, University of Edinburgh, Edinburgh EH9 3JT, United Kingdom
| | - Petra Schneider
- Centre for Immunity, Infection and Evolution, School of Biological Sciences, University of Edinburgh, Edinburgh EH9 3JT, United Kingdom
| | - Andrew F. Read
- Center for Infectious Disease Dynamics, Departments of Biology and Entomology, Pennsylvania State University, University Park, Pennsylvania 16802; and Fogarty International Center, National Institutes of Health, Bethesda, Maryland 20892
| | - Troy Day
- Departments of Biology and Mathematics and Statistics, Queen’s University, Kingston, Ontario K7L 3N6, Canada
| | - Sarah E. Reece
- Centre for Immunity, Infection and Evolution, School of Biological Sciences, University of Edinburgh, Edinburgh EH9 3JT, United Kingdom
- Institute of Immunity and Infection Research, School of Biological Sciences, University of Edinburgh, Edinburgh EH9 3JT, United Kingdom
- Institute of Evolutionary Biology, School of Biological Sciences, University of Edinburgh, Edinburgh EH9 3JT, United Kingdom
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24
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Long GH, Boots M. How can immunopathology shape the evolution of parasite virulence? Trends Parasitol 2011; 27:300-5. [PMID: 21531628 DOI: 10.1016/j.pt.2011.03.012] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2010] [Revised: 03/31/2011] [Accepted: 03/31/2011] [Indexed: 01/05/2023]
Abstract
Immunopathology (immune-mediated pathology) is a ubiquitous cause of disease during infection, but how will parasite exploitation strategies evolve in its presence? Immunopathology can act to increase parasite fitness if it increases transmission rate, but can equally act to decrease parasite fitness if it increases host mortality. The focus here is on understanding how immunopathology, mediated through different immune mechanisms, can influence parasite fitness and how experimental manipulations of the immune system can be carried out to examine this. A better understanding of how parasite fitness scales with, or responds to, immunopathology is crucial to understanding the nature of selection acting on parasite virulence traits and will allow more informed predictions to be made regarding the trajectory of parasite virulence evolution.
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Affiliation(s)
- Gráinne H Long
- Department of Animal and Plant Sciences, University of Sheffield, Western Bank, Sheffield, S10 2TN, UK.
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25
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Hendry AP, Kinnison MT, Heino M, Day T, Smith TB, Fitt G, Bergstrom CT, Oakeshott J, Jørgensen PS, Zalucki MP, Gilchrist G, Southerton S, Sih A, Strauss S, Denison RF, Carroll SP. Evolutionary principles and their practical application. Evol Appl 2011; 4:159-83. [PMID: 25567966 PMCID: PMC3352551 DOI: 10.1111/j.1752-4571.2010.00165.x] [Citation(s) in RCA: 202] [Impact Index Per Article: 15.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2010] [Accepted: 09/20/2010] [Indexed: 02/01/2023] Open
Abstract
Evolutionary principles are now routinely incorporated into medicine and agriculture. Examples include the design of treatments that slow the evolution of resistance by weeds, pests, and pathogens, and the design of breeding programs that maximize crop yield or quality. Evolutionary principles are also increasingly incorporated into conservation biology, natural resource management, and environmental science. Examples include the protection of small and isolated populations from inbreeding depression, the identification of key traits involved in adaptation to climate change, the design of harvesting regimes that minimize unwanted life-history evolution, and the setting of conservation priorities based on populations, species, or communities that harbor the greatest evolutionary diversity and potential. The adoption of evolutionary principles has proceeded somewhat independently in these different fields, even though the underlying fundamental concepts are the same. We explore these fundamental concepts under four main themes: variation, selection, connectivity, and eco-evolutionary dynamics. Within each theme, we present several key evolutionary principles and illustrate their use in addressing applied problems. We hope that the resulting primer of evolutionary concepts and their practical utility helps to advance a unified multidisciplinary field of applied evolutionary biology.
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Affiliation(s)
- Andrew P Hendry
- Redpath Museum and Department of Biology, McGill University Montreal, QC, Canada
| | | | - Mikko Heino
- Department of Biology, University of Bergen Bergen, Norway ; International Institute for Applied Systems Analysis Laxenburg, Austria ; Institute of Marine Research Bergen, Norway
| | - Troy Day
- Departments of Mathematics and Statistics and Biology, Queen's University Kingston, ON, Canada
| | - Thomas B Smith
- Center for Tropical Research, Institute of the Environment, University of California Los Angeles, CA, USA ; Department of Ecology and Evolutionary Biology, University of California Los Angeles, CA, USA
| | - Gary Fitt
- CSIRO Entomology and Cotton Catchment Communities CRC, Long Pocket Laboratories Indooroopilly, Qld, Australia
| | - Carl T Bergstrom
- Department of Biology, University of Washington Seattle, WA, USA
| | - John Oakeshott
- CSIRO Entomology, Black Mountain Canberra, ACT, Australia
| | - Peter S Jørgensen
- Center for Macroecology, Evolution and Climate, Department of Biology, University of Copenhagen Copenhagen, Denmark
| | - Myron P Zalucki
- School of Biological Sciences, The University of Queensland Brisbane, Qld, Australia
| | - George Gilchrist
- Division of Environmental Biology, National Science Foundation Arlington, VA, USA
| | | | - Andrew Sih
- Department of Environmental Science and Policy, University of California Davis, CA, USA
| | - Sharon Strauss
- Section of Evolution and Ecology, University of California Davis, CA, USA
| | - Robert F Denison
- Ecology Evolution and Behavior, University of Minnesota Saint Paul, MN, USA
| | - Scott P Carroll
- Institute for Contemporary Evolution Davis, CA, USA ; Department of Entomology, University of California Davis, CA, USA
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