Camden D Gowler, Haley Essington, Bruce O'Brien, Clara L Shaw, Rebecca W Bilich, Patrick A Clay, Meghan A Duffy
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引用次数: 3
Abstract
Virulence, the degree to which a pathogen harms its host, is an important but poorly understood aspect of host-pathogen interactions. Virulence is not static, instead depending on ecological context and potentially evolving rapidly. For instance, at the start of an epidemic, when susceptible hosts are plentiful, pathogens may evolve increased virulence if this maximizes their intrinsic growth rate. However, if host density declines during an epidemic, theory predicts evolution of reduced virulence. Although well-studied theoretically, there is still little empirical evidence for virulence evolution in epidemics, especially in natural settings with native host and pathogen species. Here, we used a combination of field observations and lab assays in the Daphnia-Pasteuria model system to look for evidence of virulence evolution in nature. We monitored a large, naturally occurring outbreak of Pasteuria ramosa in Daphnia dentifera, where infection prevalence peaked at ~ 40% of the population infected and host density declined precipitously during the outbreak. In controlled infections in the lab, lifespan and reproduction of infected hosts was lower than that of unexposed control hosts and of hosts that were exposed but not infected. We did not detect any significant changes in host resistance or parasite infectivity, nor did we find evidence for shifts in parasite virulence (quantified by host lifespan and number of clutches produced by hosts). However, over the epidemic, the parasite evolved to produce significantly fewer spores in infected hosts. While this finding was unexpected, it might reflect previously quantified tradeoffs: parasites in high mortality (e.g., high predation) environments shift from vegetative growth to spore production sooner in infections, reducing spore yield. Future studies that track evolution of parasite spore yield in more populations, and that link those changes with genetic changes and with predation rates, will yield better insight into the drivers of parasite evolution in the wild.
Supplementary information: The online version contains supplementary material available at 10.1007/s10682-022-10169-6.
期刊介绍：
Evolutionary Ecology is a concept-oriented journal of biological research at the interface of ecology and evolution. We publish papers that therefore integrate both fields of research: research that seeks to explain the ecology of organisms in the context of evolution, or patterns of evolution as explained by ecological processes.
The journal publishes original research and discussion concerning the evolutionary ecology of organisms. These may include papers addressing evolutionary aspects of population ecology, organismal interactions and coevolution, behaviour, life histories, communication, morphology, host-parasite interactions and disease ecology, as well as ecological aspects of genetic processes. The objective is to promote the conceptual, theoretical and empirical development of ecology and evolutionary biology; the scope extends to any organism or system.
In additional to Original Research articles, we publish Review articles that survey recent developments in the field of evolutionary ecology; Ideas & Perspectives articles which present new points of view and novel hypotheses; and Comments on articles recently published in Evolutionary Ecology or elsewhere. We also welcome New Tests of Existing Ideas - testing well-established hypotheses but with broader data or more methodologically rigorous approaches; - and shorter Natural History Notes, which aim to present new observations of organismal biology in the wild that may provide inspiration for future research. As of 2018, we now also invite Methods papers, to present or review new theoretical, practical or analytical methods used in evolutionary ecology.
Students & Early Career Researchers: We particularly encourage, and offer incentives for, submission of Reviews, Ideas & Perspectives, and Methods papers by students and early-career researchers (defined as being within one year of award of a PhD degree) – see Students & Early Career Researchers
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