Host Life Span and the Evolution of Resistance Characteristics

Miller, Martin R.; White, Andrew; Boots, Michael

doi:10.1111/j.1558-5646.2007.00001.x

Cited by 122 publications

(196 citation statements)

References 47 publications

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“…should be maximized in species with high or intermediate lifespan [4,[35][36][37][38]. Simply put, short-lived hosts are unlikely to encounter the same pathogen twice and should therefore not invest in memory.…”

Section: Discussionmentioning

confidence: 99%

Evolution of transgenerational immunity in invertebrates

et al. 2016

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Over a decade ago, the discovery of transgenerational immunity in invertebrates shifted existing paradigms on the lack of sophistication of their immune system. Nonetheless, the prevalence of this trait and the ecological factors driving its evolution in invertebrates remain poorly understood. Here, we develop a theoretical host -parasite model and predict that long lifespan and low dispersal should promote the evolution of transgenerational immunity. We also predict that in species that produce both philopatric and dispersing individuals, it may pay to have a plastic allocation strategy with a higher transgenerational immunity investment in philopatric offspring because they are more likely to encounter locally adapted pathogens. We review all experimental studies published to date, comprising 21 invertebrate species in nine different orders, and we show that, as expected, longevity and dispersal correlate with the transfer of immunity to offspring. The validity of our prediction regarding the plasticity of investment in transgenerational immunity remains to be tested in invertebrates, but also in vertebrate species. We discuss the implications of our work for the study of the evolution of immunity, and we suggest further avenues of research to expand our knowledge of the impact of transgenerational immune protection in host -parasite interactions.

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Section: Discussionmentioning

confidence: 99%

Evolution of transgenerational immunity in invertebrates

et al. 2016

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“…Although there is a substantial body of literature on host avoidance evolutionary and coevolutionary dynamics (e.g. [2,3,[5][6][7][8][9][10][11][12][13][14]), a key assumption of this theory is that the host has a fixed resistance strategy, which does not exhibit plasticity. As a result, when considering the host-pathogen coevolutionary dynamics, the focus is upon a symmetric game [15]: the pathogen strategy (e.g.…”

Section: Introductionmentioning

confidence: 99%

Pathogen evolution under host avoidance plasticity

McLeod

Day

2015

Proc. R. Soc. B.

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Host resistance consists of defences that limit pathogen burden, and can be classified as either adaptations targeting recovery from infection or those focused upon infection avoidance. Conventional theory treats avoidance as a fixed strategy which does not vary from one interaction to the next. However, there is increasing empirical evidence that many avoidance strategies are triggered by external stimuli, and thus should be treated as phenotypically plastic responses. Here, we consider the implications of avoidance plasticity for host-pathogen coevolution. We uncover a number of predictions challenging current theory. First, in the absence of pathogen trade-offs, plasticity can restrain pathogen evolution; moreover, the pathogen exploits conditions in which the host would otherwise invest less in resistance, causing resistance escalation. Second, when transmission trades off with pathogen-induced mortality, plasticity encourages avirulence, resulting in a superior fitness outcome for both host and pathogen. Third, plasticity ensures the sterilizing effect of pathogens has consequences for pathogen evolution. When pathogens castrate hosts, selection forces them to minimize mortality virulence; moreover, when transmission trades off with sterility alone, resistance plasticity is sufficient to prevent pathogens from evolving to fully castrate.

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“…Constitutive costs of immunity are those incurred in the development and maintenance of the immune system, whereas facultative costs are those incurred in the deployment of the immune system (or indeed any inducible defence system [36]). The vast majority of models for the evolution of host recovery rate, in particular have assumed that increased recovery rate carries a constitutive cost-both susceptible and infected hosts have lower reproductive rates ( [25,28,29,31], but see [27]). In reality, of course, organisms invest in both constitutive and facultative defences.…”

Section: Discussionmentioning

confidence: 99%

Evolution of hosts paying manifold costs of defence

2015

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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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Host Life Span and the Evolution of Resistance Characteristics

Cited by 122 publications

References 47 publications

Evolution of transgenerational immunity in invertebrates

Evolution of transgenerational immunity in invertebrates

Pathogen evolution under host avoidance plasticity

Evolution of hosts paying manifold costs of defence

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