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Mestre A, Butlin RK, Hortal J, Rafajlović M. Adaptive colonization across a parasitism-mutualism gradient. Evol Lett 2024; 8:340-350. [PMID: 38818421 PMCID: PMC11134462 DOI: 10.1093/evlett/qrad061] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2023] [Revised: 11/16/2023] [Accepted: 12/18/2023] [Indexed: 06/01/2024] Open
Abstract
Adaptive colonization is a process wherein a colonizing population exhibits an adaptive change in response to a novel environment, which may be critical to its establishment. To date, theoretical models of adaptive colonization have been based on single-species introductions. However, given their pervasiveness, symbionts will frequently be co-introduced with their hosts to novel areas. We present an individual-based model to investigate adaptive colonization by hosts and their symbionts across a parasite-mutualist continuum. The host must adapt in order to establish itself in the novel habitat, and the symbiont must adapt to track evolutionary change in the host. First, we classify the qualitative shifts in the outcome that can potentially be driven by non-neutral effects of the symbiont-host interaction into three main types: parasite-driven co-extinction, parasite release, and mutualistic facilitation. Second, we provide a detailed description of a specific example for each type of shift. Third, we disentangle how the interplay between symbiont transmissibility, host migration, and selection strength determines: (a) which type of shift is more likely to occur and (b) the size of the interaction effects necessary to produce it. Overall, we demonstrate the crucial role of host and symbiont dispersal scales in shaping the impacts of parasitism and mutualism on adaptive colonization.
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Affiliation(s)
- Alexandre Mestre
- Cavanilles Institute of Biodiversity and Evolutionary Biology, University of Valencia, Paterna, Spain
| | - Roger K Butlin
- Department of Marine Sciences, University of Gothenburg, Gothenburg, Sweden
- Ecology and Evolutionary Biology, School of Bioscience, The University of Sheffield, Sheffield, United Kingdom
| | - Joaquín Hortal
- Department of Biogeography and Global Change, Museo Nacional de Ciencias Naturales (MNCN-CSIC), Madrid, Spain
- cE3c—Centre for Ecology, Evolution and Environmental Changes, Faculdade de Ciências, Universidade de Lisboa, Lisboa, Portugal
- Departamento de Ecologia, Instituto de Ciências Biológicas, Universidade Federal de Goiás, Goiânia, GO, Brazil
| | - Marina Rafajlović
- Department of Marine Sciences, University of Gothenburg, Gothenburg, Sweden
- Centre for Marine Evolutionary Biology, University of Gothenburg, Gothenburg, Sweden
- Gothenburg Global Biodiversity Centre, University of Gothenburg, Gothenburg, Sweden
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Wilber MQ, DeMarchi JA, Briggs CJ, Streipert S. Rapid Evolution of Resistance and Tolerance Leads to Variable Host Recoveries following Disease-Induced Declines. Am Nat 2024; 203:535-550. [PMID: 38635360 DOI: 10.1086/729437] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/20/2024]
Abstract
AbstractRecoveries of populations that have suffered severe disease-induced declines are being observed across disparate taxa. Yet we lack theoretical understanding of the drivers and dynamics of recovery in host populations and communities impacted by infectious disease. Motivated by disease-induced declines and nascent recoveries in amphibians, we developed a model to ask the following question: How does the rapid evolution of different host defense strategies affect the transient recovery trajectories of hosts following pathogen invasion and disease-induced declines? We found that while host life history is predictably a major driver of variability in population recovery trajectories (including declines and recoveries), populations that use different host defense strategies (i.e., tolerance, avoidance resistance, and intensity-reduction resistance) experience notably different recoveries. In single-species host populations, populations evolving tolerance recovered on average four times slower than populations evolving resistance. Moreover, while populations using avoidance resistance strategies had the fastest potential recovery rates, these populations could get trapped in long transient states at low abundance prior to recovery. In contrast, the recovery of populations evolving intensity-reduction resistance strategies were more consistent across ecological contexts. Overall, host defense strategies strongly affect the transient dynamics of population recovery and may affect the ultimate fate of real populations recovering from disease-induced declines.
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Berger L, Skerratt LF, Kosch TA, Brannelly LA, Webb RJ, Waddle AW. Advances in Managing Chytridiomycosis for Australian Frogs: Gradarius Firmus Victoria. Annu Rev Anim Biosci 2024; 12:113-133. [PMID: 38358840 DOI: 10.1146/annurev-animal-021122-100823] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/17/2024]
Abstract
Extensive knowledge gains from research worldwide over the 25 years since the discovery of chytridiomycosis can be used for improved management. Strategies that have saved populations in the short term and/or enabled recovery include captive breeding, translocation into disease refugia, translocation from resistant populations, disease-free exclosures, and preservation of disease refuges with connectivity to previous habitat, while antifungal treatments have reduced mortality rates in the wild. Increasing host resistance is the goal of many strategies under development, including vaccination and targeted genetic interventions. Pathogen-directed strategies may be more challenging but would have broad applicability. While the search for the silver bullet solution continues, we should value targeted local interventions that stop extinction and buy time for evolution of resistance or development of novel solutions. As for most invasive species and infectious diseases, we need to accept that ongoing management is necessary. For species continuing to decline, proactive deployment and assessment of promising interventions are more valid than a hands-off, do-no-harm approach that will likely allow further extinctions.
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Affiliation(s)
- Lee Berger
- One Health Research Group, Melbourne Veterinary School, Faculty of Science, University of Melbourne, Werribee, Victoria, Australia; , , , ,
| | - Lee F Skerratt
- One Health Research Group, Melbourne Veterinary School, Faculty of Science, University of Melbourne, Werribee, Victoria, Australia; , , , ,
| | - Tiffany A Kosch
- One Health Research Group, Melbourne Veterinary School, Faculty of Science, University of Melbourne, Werribee, Victoria, Australia; , , , ,
| | - Laura A Brannelly
- One Health Research Group, Melbourne Veterinary School, Faculty of Science, University of Melbourne, Werribee, Victoria, Australia; , , , ,
| | - Rebecca J Webb
- One Health Research Group, Melbourne Veterinary School, Faculty of Science, University of Melbourne, Werribee, Victoria, Australia; , , , ,
| | - Anthony W Waddle
- One Health Research Group, Melbourne Veterinary School, Faculty of Science, University of Melbourne, Werribee, Victoria, Australia; , , , ,
- Applied Biosciences, Macquarie University, Sydney, New South Wales, Australia;
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Erens J, Preissler K, Speybroeck J, Beukema W, Spitzen-van der Sluijs A, Stark T, Laudelout A, Kinet T, Schmidt BR, Martel A, Steinfartz S, Pasmans F. Divergent population responses following salamander mass mortalities and declines driven by the emerging pathogen Batrachochytrium salamandrivorans. Proc Biol Sci 2023; 290:20230510. [PMID: 37752840 PMCID: PMC10523083 DOI: 10.1098/rspb.2023.0510] [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: 03/02/2023] [Accepted: 08/31/2023] [Indexed: 09/28/2023] Open
Abstract
Understanding wildlife responses to novel threats is vital in counteracting biodiversity loss. The emerging pathogen Batrachochytrium salamandrivorans (Bsal) causes dramatic declines in European salamander populations, and is considered an imminent threat to global amphibian biodiversity. However, real-life disease outcomes remain largely uncharacterized. We performed a multidisciplinary assessment of the longer-term impacts of Bsal on highly susceptible fire salamander (Salamandra salamandra) populations, by comparing four of the earliest known outbreak sites to uninfected sites. Based on large-scale monitoring efforts, we found population persistence in strongly reduced abundances to over a decade after Bsal invasion, but also the extinction of an initially small-sized population. In turn, we found that host responses varied, and Bsal detection remained low, within surviving populations. Demographic analyses indicated an ongoing scarcity of large reproductive adults with potential for recruitment failure, while spatial comparisons indicated a population remnant persisting within aberrant habitat. Additionally, we detected no early signs of severe genetic deterioration, yet nor of increased host resistance. Beyond offering additional context to Bsal-driven salamander declines, results highlight how the impacts of emerging hypervirulent pathogens can be unpredictable and vary across different levels of biological complexity, and how limited pathogen detectability after population declines may complicate surveillance efforts.
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Affiliation(s)
- Jesse Erens
- Wildlife Health Ghent, Faculty of Veterinary Medicine, Ghent University, Ghent, Belgium
| | | | | | - Wouter Beukema
- Wildlife Health Ghent, Faculty of Veterinary Medicine, Ghent University, Ghent, Belgium
- Reptile, Amphibian & Fish Conservation Netherlands (RAVON), Nijmegen, the Netherlands
| | - Annemarieke Spitzen-van der Sluijs
- Reptile, Amphibian & Fish Conservation Netherlands (RAVON), Nijmegen, the Netherlands
- Institute for Water and Wetland Research, Animal Ecology and Physiology, Radboud University, Nijmegen, the Netherlands
| | - Tariq Stark
- Reptile, Amphibian & Fish Conservation Netherlands (RAVON), Nijmegen, the Netherlands
| | | | | | - Benedikt R. Schmidt
- Department of Evolutionary Biology and Environmental Studies, University of Zurich, Zurich, Switzerland
- Info fauna karch, Neuchâtel, Switzerland
| | - An Martel
- Wildlife Health Ghent, Faculty of Veterinary Medicine, Ghent University, Ghent, Belgium
| | | | - Frank Pasmans
- Wildlife Health Ghent, Faculty of Veterinary Medicine, Ghent University, Ghent, Belgium
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Christie MR, McNickle GG. Negative frequency dependent selection unites ecology and evolution. Ecol Evol 2023; 13:e10327. [PMID: 37484931 PMCID: PMC10361363 DOI: 10.1002/ece3.10327] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2023] [Revised: 06/02/2023] [Accepted: 07/07/2023] [Indexed: 07/25/2023] Open
Abstract
From genes to communities, understanding how diversity is maintained remains a fundamental question in biology. One challenging to identify, yet potentially ubiquitous, mechanism for the maintenance of diversity is negative frequency dependent selection (NFDS), which occurs when entities (e.g., genotypes, life history strategies, species) experience a per capita reduction in fitness with increases in relative abundance. Because NFDS allows rare entities to increase in frequency while preventing abundant entities from excluding others, we posit that negative frequency dependent selection plays a central role in the maintenance of diversity. In this review, we relate NFDS to coexistence, identify mechanisms of NFDS (e.g., mutualism, predation, parasitism), review strategies for identifying NFDS, and distinguish NFDS from other mechanisms of coexistence (e.g., storage effects, fluctuating selection). We also emphasize that NFDS is a key place where ecology and evolution intersect. Specifically, there are many examples of frequency dependent processes in ecology, but fewer cases that link this process to selection. Similarly, there are many examples of selection in evolution, but fewer cases that link changes in trait values to negative frequency dependence. Bridging these two well-developed fields of ecology and evolution will allow for mechanistic insights into the maintenance of diversity at multiple levels.
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Affiliation(s)
- Mark R. Christie
- Department of Biological SciencesPurdue UniversityWest LafayetteIndianaUSA
- Department of Forestry and Natural ResourcesPurdue UniversityWest LafayetteIndianaUSA
| | - Gordon G. McNickle
- Department of Biological SciencesPurdue UniversityWest LafayetteIndianaUSA
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Westphal GH, Stewart Merrill TE. Partitioning variance in immune traits in a zooplankton host-Fungal parasite system. Ecol Evol 2022; 12:e9640. [PMID: 36545366 PMCID: PMC9763022 DOI: 10.1002/ece3.9640] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2022] [Revised: 11/21/2022] [Accepted: 11/29/2022] [Indexed: 12/24/2022] Open
Abstract
Host immune traits arise from both genetic and environmental sources of variation. When immune traits have a strong genetic basis, the presence and severity of disease in a population may influence the distribution of those traits. Our study addressed how two immune-related traits (gut penetrability and the hemocyte response) are shaped by genetic and environmental sources of variation, and how the presence of a virulent disease altered the relative frequency of these traits in natural populations. Daphnia dentifera hosts were sampled from five Indiana lakes between June and December 2017 before and during epidemics of their fungal pathogen, Metschnikowia bicuspidata. Collected Daphnia were experimentally exposed to Metschnikowia and assayed for their gut penetrability, hemocyte response, and multi-locus genotype. Mixed-effects models were constructed to partition variance in immune traits between genetic and environmental sources. We then isolated the genetic sources to produce genotype-specific estimates of immune traits for each multi-locus genotype. Finally, we assessed the relative frequency and dynamics of genotypes during epidemics and asked whether genotypes with more robust immune responses increased in frequency during epidemics. Although genotype was an important source of variation for both gut penetrability and the hemocyte response, environmental factors (e.g., resource availability, Metschnikowia prevalence, and co-infection) still explained a large portion of observed variation, suggesting a high degree of flexibility in Daphnia immune traits. Additionally, no significant associations were detected between a genotype's immune traits and its frequency in a population. Our study highlights the power of variance partitioning in understanding the factors driving variation in Daphnia traits and motivates further research on immunological flexibility and the ecological drivers of immune variation.
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Affiliation(s)
- Grace H. Westphal
- School of Integrative BiologyUniversity of Illinois Urbana‐ChampaignChampaignIllinoisUSA,Department of Biological ScienceFlorida State UniversityTallahasseeFloridaUSA
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Aubier TG, Olazcuaga L. Digest: Evolutionary rescue following the introduction of a pathogen . Evolution 2021; 75:2998-2999. [PMID: 34558060 DOI: 10.1111/evo.14361] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2021] [Accepted: 08/30/2021] [Indexed: 11/27/2022]
Abstract
To what extent can adaptive evolution rescue a population from extinction following the introduction of a pathogen? Searle and Christie (2021) show how evolutionary rescues in host-pathogen systems may differ from those that occur in response to abiotic changes. In particular, they pinpoint how epidemiological feedback and pathogen evolution, inherent to host-pathogen systems, can greatly affect the likelihood of rescue.
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Affiliation(s)
- Thomas G Aubier
- Department of Biology, University of North Carolina, Chapel Hill, North Carolina, USA
| | - Laure Olazcuaga
- Department of Agricultural Biology, Colorado State University, Fort Collins, Colorado, USA
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