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Buckingham LJ, Ashby B. Separation of evolutionary timescales in coevolving species. J Theor Biol 2024; 579:111688. [PMID: 38096978 DOI: 10.1016/j.jtbi.2023.111688] [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] [Received: 07/19/2023] [Revised: 10/24/2023] [Accepted: 11/27/2023] [Indexed: 12/23/2023]
Abstract
Many coevolutionary processes, including host-parasite and host-symbiont interactions, involve one species or trait which evolves much faster than the other. Whether or not a coevolutionary trajectory converges depends on the relative rates of evolutionary change in the two species, and so current adaptive dynamics approaches generally either determine convergence stability by considering arbitrary (often comparable) rates of evolutionary change or else rely on necessary or sufficient conditions for convergence stability. We propose a method for determining convergence stability in the case where one species is expected to evolve much faster than the other. This requires a second separation of timescales, which assumes that the faster evolving species will reach its evolutionary equilibrium (if one exists) before a new mutation arises in the more slowly evolving species. This method, which is likely to be a reasonable approximation for many coevolving species, both provides straightforward conditions for convergence stability and is less computationally expensive than traditional analysis of coevolution models, as it reduces the trait space from a two-dimensional plane to a one-dimensional manifold. In this paper, we present the theory underlying this new separation of timescales and provide examples of how it could be used to determine coevolutionary outcomes from models.
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Affiliation(s)
- Lydia J Buckingham
- Department of Mathematical Sciences, University of Bath, Bath, UK; Milner Centre for Evolution, University of Bath, Bath, UK.
| | - Ben Ashby
- Department of Mathematical Sciences, University of Bath, Bath, UK; Milner Centre for Evolution, University of Bath, Bath, UK; Department of Mathematics, Simon Fraser University, Burnaby, BC, Canada; The Pacific Institute on Pathogens, Pandemics and Society (PIPPS), Simon Fraser University, Burnaby, BC, Canada
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Buckingham LJ, Ashby B. Coevolutionary theory of hosts and parasites. J Evol Biol 2022; 35:205-224. [PMID: 35030276 PMCID: PMC9305583 DOI: 10.1111/jeb.13981] [Citation(s) in RCA: 19] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2021] [Revised: 12/14/2021] [Accepted: 01/05/2022] [Indexed: 11/30/2022]
Abstract
Host and parasite evolution are closely intertwined, with selection for adaptations and counter-adaptations forming a coevolutionary feedback loop. Coevolutionary dynamics are often difficult to intuit due to these feedbacks and are hard to demonstrate empirically in most systems. Theoretical models have therefore played a crucial role in shaping our understanding of host-parasite coevolution. Theoretical models vary widely in their assumptions, approaches and aims, and such variety makes it difficult, especially for non-theoreticians and those new to the field, to: (1) understand how model approaches relate to one another; (2) identify key modelling assumptions; (3) determine how model assumptions relate to biological systems; and (4) reconcile the results of different models with contrasting assumptions. In this review, we identify important model features, highlight key results and predictions and describe how these pertain to model assumptions. We carry out a literature survey of theoretical studies published since the 1950s (n = 219 papers) to support our analysis. We identify two particularly important features of models that tend to have a significant qualitative impact on the outcome of host-parasite coevolution: population dynamics and the genetic basis of infection. We also highlight the importance of other modelling features, such as stochasticity and whether time proceeds continuously or in discrete steps, that have received less attention but can drastically alter coevolutionary dynamics. We finish by summarizing recent developments in the field, specifically the trend towards greater model complexity, and discuss likely future directions for research.
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Affiliation(s)
- Lydia J. Buckingham
- Department of Mathematical SciencesUniversity of BathBathUK
- Milner Centre for EvolutionUniversity of BathBathUK
| | - Ben Ashby
- Department of Mathematical SciencesUniversity of BathBathUK
- Milner Centre for EvolutionUniversity of BathBathUK
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Bagchi B, Corbel Q, Khan I, Payne E, Banerji D, Liljestrand-Rönn J, Martinossi-Allibert I, Baur J, Sayadi A, Immonen E, Arnqvist G, Söderhäll I, Berger D. Sexual conflict drives micro- and macroevolution of sexual dimorphism in immunity. BMC Biol 2021; 19:114. [PMID: 34078377 PMCID: PMC8170964 DOI: 10.1186/s12915-021-01049-6] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2021] [Accepted: 05/07/2021] [Indexed: 02/07/2023] Open
Abstract
BACKGROUND Sexual dimorphism in immunity is believed to reflect sex differences in reproductive strategies and trade-offs between competing life history demands. Sexual selection can have major effects on mating rates and sex-specific costs of mating and may thereby influence sex differences in immunity as well as associated host-pathogen dynamics. Yet, experimental evidence linking the mating system to evolved sexual dimorphism in immunity are scarce and the direct effects of mating rate on immunity are not well established. Here, we use transcriptomic analyses, experimental evolution and phylogenetic comparative methods to study the association between the mating system and sexual dimorphism in immunity in seed beetles, where mating causes internal injuries in females. RESULTS We demonstrate that female phenoloxidase (PO) activity, involved in wound healing and defence against parasitic infections, is elevated relative to males. This difference is accompanied by concomitant sex differences in the expression of genes in the prophenoloxidase activating cascade. We document substantial phenotypic plasticity in female PO activity in response to mating and show that experimental evolution under enforced monogamy (resulting in low remating rates and reduced sexual conflict relative to natural polygamy) rapidly decreases female (but not male) PO activity. Moreover, monogamous females had evolved increased tolerance to bacterial infection unrelated to mating, implying that female responses to costly mating may trade off with other aspects of immune defence, an hypothesis which broadly accords with the documented sex differences in gene expression. Finally, female (but not male) PO activity shows correlated evolution with the perceived harmfulness of male genitalia across 12 species of seed beetles, suggesting that sexual conflict has a significant influence on sexual dimorphisms in immunity in this group of insects. CONCLUSIONS Our study provides insights into the links between sexual conflict and sexual dimorphism in immunity and suggests that selection pressures moulded by mating interactions can lead to a sex-specific mosaic of immune responses with important implications for host-pathogen dynamics in sexually reproducing organisms.
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Affiliation(s)
- Basabi Bagchi
- Department of Biology, Ashoka University, Sonipat, India
| | - Quentin Corbel
- Department of Ecology and Genetics, Program of Animal Ecology, Evolutionary Biology Centre, Uppsala University, Uppsala, Sweden
- Cavanilles Institute of Biodiversity and Evolutionary Biology, University of Valencia, Valencia, Spain
| | - Imroze Khan
- Department of Biology, Ashoka University, Sonipat, India
| | - Ellen Payne
- Department of Ecology and Genetics, Program of Animal Ecology, Evolutionary Biology Centre, Uppsala University, Uppsala, Sweden
| | | | - Johanna Liljestrand-Rönn
- Department of Ecology and Genetics, Program of Animal Ecology, Evolutionary Biology Centre, Uppsala University, Uppsala, Sweden
| | - Ivain Martinossi-Allibert
- Department of Ecology and Genetics, Program of Animal Ecology, Evolutionary Biology Centre, Uppsala University, Uppsala, Sweden
- Department of Organismal Biology, Evolutionary Biology Centre, Uppsala University, Uppsala, Sweden
| | - Julian Baur
- Department of Ecology and Genetics, Program of Animal Ecology, Evolutionary Biology Centre, Uppsala University, Uppsala, Sweden
| | - Ahmed Sayadi
- Department of Ecology and Genetics, Program of Animal Ecology, Evolutionary Biology Centre, Uppsala University, Uppsala, Sweden
- Department of Chemistry, Biochemistry, Uppsala University, Uppsala, Sweden
| | - Elina Immonen
- Department of Ecology and Genetics, Program of Evolutionary Biology, Evolutionary Biology Centre, Uppsala University, Uppsala, Sweden
| | - Göran Arnqvist
- Department of Ecology and Genetics, Program of Animal Ecology, Evolutionary Biology Centre, Uppsala University, Uppsala, Sweden
| | - Irene Söderhäll
- Department of Organismal Biology, Program of Comparative Physiology, Uppsala University, Uppsala, Sweden
| | - David Berger
- Department of Ecology and Genetics, Program of Animal Ecology, Evolutionary Biology Centre, Uppsala University, Uppsala, Sweden.
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Lasala JA, Hughes C, Wyneken J. Female loggerhead sea turtles ( Caretta caretta L.) rarely remate during nesting season. Ecol Evol 2020; 10:163-174. [PMID: 31988720 PMCID: PMC6972835 DOI: 10.1002/ece3.5869] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2019] [Accepted: 08/19/2019] [Indexed: 11/05/2022] Open
Abstract
The goal of this study was to assess the consequences of single versus multiple paternity by identifying paternity of clutches per female to identify whether there were detectable costs or benefits. Multiple mating can occur when the benefits of mating outweigh the costs, but if costs and benefits are equal, no pattern is expected. Previous research on loggerhead sea turtle (Caretta caretta) populations found male-biased breeding sex ratios and multiple mating by many females nesting in southwestern Florida. A sample of nesting loggerhead females who laid more than one nest over the course of the season and a subset of their hatchlings were examined from 36 clutches in 2016 on Sanibel Island, Florida. Males that fathered hatchlings in the first clutch sampled were identified in subsequent clutches. Interestingly, 75% of the females analyzed had mated singly. No male was represented in more than one female's clutches. The results suggest that females likely mate at the beginning of the season and use stored sperm for multiple clutches. Evidence for mating between laying events was limited. There was no consistent pattern across the subsequent multiple paternity clutches, suggesting benefits to loggerhead females likely equal their costs and subsequent mating is likely determined by female preference.
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Affiliation(s)
- Jacob A. Lasala
- Florida Atlantic UniversityBoca RatonFLUSA
- Mote Marine LaboratorySarasotaFLUSA
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Ashby B. Antagonistic coevolution between hosts and sexually transmitted infections. Evolution 2019; 74:43-56. [PMID: 31732970 PMCID: PMC6973023 DOI: 10.1111/evo.13883] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2019] [Revised: 09/06/2019] [Accepted: 10/09/2019] [Indexed: 01/13/2023]
Abstract
Sexually transmitted infections (STIs) are predicted to play an important role in the evolution of host mating strategies, and vice versa, yet our understanding of host‐STI coevolution is limited. Previous theoretical work has shown mate choice can evolve to prevent runaway STI virulence evolution in chronic, sterilizing infections. Here, I generalize this theory to examine how a broader range of life‐history traits influence coevolution; specifically, how host preferences for healthy mates and STI virulence coevolve when infections are acute and can cause mortality or sterility, and hosts do not form long‐term sexual partnerships. I show that mate choice reduces both mortality and sterility virulence, with qualitatively different outcomes depending on the mode of virulence, costs associated with mate choice, recovery rates, and host lifespan. For example, fluctuating selection—a key finding in previous work—is most likely when hosts have moderate lifespans, STIs cause sterility and long infections, and costs of mate choice are low. The results reveal new insights into the coevolution of mate choice and STI virulence as different life‐history traits vary, providing increased support for parasite‐mediated sexual selection as a potential driver of host mate choice, and mate choice as a constraint on the evolution of virulence.
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Affiliation(s)
- Ben Ashby
- Department of Mathematical Sciences, University of Bath, Bath, BA2 7AY, United Kingdom
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Abstract
The moment of the fertilization of an egg by a spermatozoon-the point of "sperm success"-is a key milestone in the biology of sexually reproducing species and is a fundamental requirement for offspring production. Fertilization also represents the culmination of a suite of sexually selected processes in both sexes and is commonly used as a landmark to measure reproductive success. Sperm success is heavily dependent upon interactions with other key aspects of male and female biology, with the immune system among the most important. The immune system is vital to maintaining health in both sexes; however, immune reactions can also have antagonistic effects on sperm success. The effects of immunity on sperm success are diverse, and may include trade-offs in the male between investment in the production or protection of sperm, as well as more direct, hostile, immune responses to sperm within the female, and potentially the male, reproductive tract. Here, we review current understanding of where the biology of immunity and sperm meet, and identify the gaps in our knowledge.
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Affiliation(s)
- Stuart Wigby
- Edward Grey Institute, Department of Zoology, University of Oxford, Oxford, United Kingdom.
| | - Susan S Suarez
- Departments of Biomedical Sciences (SSS), Entomology (BPL), and Molecular Biology and Genetics (MFW), Cornell University, Ithaca, NY, United States
| | - Brian P Lazzaro
- Departments of Biomedical Sciences (SSS), Entomology (BPL), and Molecular Biology and Genetics (MFW), Cornell University, Ithaca, NY, United States
| | - Tommaso Pizzari
- Edward Grey Institute, Department of Zoology, University of Oxford, Oxford, United Kingdom
| | - Mariana F Wolfner
- Departments of Biomedical Sciences (SSS), Entomology (BPL), and Molecular Biology and Genetics (MFW), Cornell University, Ithaca, NY, United States
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