ORCID Profile
0000-0002-2219-784X
Current Organisation
Institut des Sciences de l'Evolution de Montpellier
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Publisher: Cold Spring Harbor Laboratory
Date: 31-01-2020
DOI: 10.1101/2020.01.31.928150
Abstract: Eco-evolutionary processes may play an important role in the spatial spread of infectious disease. Current theory predicts more exploitative parasites to evolve in highly connected populations or at the front of spreading epidemics. However, many parasites rely on host dispersal to reach new populations. This may lead to conflict between local transmission and global spread, possibly counteracting selection for higher virulence. Here, we used the freshwater host Paramecium caudatum and its bacterial parasite Holospora undulata to investigate parasite evolution under an experimental range expansion scenario with natural host dispersal. We find that parasites evolving at experimental range fronts favoured higher dispersal rates of infected hosts than did parasites evolving in core populations. Front parasites further showed lower levels of virulence (host ision and survival) and delayed development of infection, consistent with parameter estimates from an epidemiological model that we fitted on experimental time-series data. This combined evidence suggests an evolutionary trade-off between virulence and host-mediated dispersal, with a concomitant reduction in the investment into horizontal transmission. Our experiment illustrates how parasite evolution can be shaped by ergent selection encountered in different segments of an epidemic wave. Such an interplay between demography and spatial selection has important implications for the understanding and management of emerging diseases, and, more generally, for biological invasions and other non-equilibrium scenarios of spreading populations. What drives parasite evolution in spatially expanding epidemics? Many parasites require dispersal of infected hosts to reach new patches, and this may produce specific adaptations enhancing spatial spread. We performed experimental range expansions in an aquatic model system, with natural dispersal of infected hosts. Parasites from experimental range fronts were less virulent and interfered less with host dispersal, but also invested less in horizontal transmission than parasites from the range core. Thus, dispersal adaptation at the front may come at a cost of reduced horizontal transmission, a trade-off rarely considered in theoretical models on parasite virulence evolution. These results have important implications in the context of emerging diseases, and for parasite evolution during biological invasions or other spatial non-equilibrium scenarios.
Publisher: Cold Spring Harbor Laboratory
Date: 29-01-2020
DOI: 10.1101/2020.01.29.924498
Abstract: Rapid evolutionary change during range expansions can lead to erging range core and front populations, with the emergence of dispersal syndromes (coupled responses in dispersal and life-history traits). Besides intraspecific effects, range expansions may be impacted by interspecific interactions such as parasitism. Yet, despite the potentially large impact of parasites imposing additional selective pressures on the host, their role on range expansions remains largely unexplored. Using microcosm populations of the ciliate Paramecium caudatum and its bacterial parasite Holospora undulata , we studied experimental range expansions under parasite presence or absence. We found that the interaction of range expansion and parasite treatments affected the evolution of host dispersal syndromes. Namely, front populations showed different associations of population growth parameters and swimming behaviours than core populations, indicating ergent evolution. Parasitism reshaped trait associations, with hosts evolved in the presence of the parasite exhibiting overall increased resistance and reduced dispersal. Nonetheless, when comparing infected range core and front populations, we found a positive association, suggesting joint evolution of resistance and dispersal at the front. We conclude that host-parasite interactions during range expansions can change evolutionary trajectories this in turn may feed back on the ecological dynamics of the range expansion and parasite epidemics.
Publisher: Cold Spring Harbor Laboratory
Date: 31-07-2020
DOI: 10.1101/2020.07.30.228742
Abstract: Dispersal is a central determinant of spatial dynamics in communities and ecosystems, and various ecological factors can shape the evolution of constitutive and plastic dispersal behaviours. One important driver of dispersal plasticity is the biotic environment. Parasites, for ex le, influence the internal condition of infected hosts and define external patch quality. Thus state-dependent dispersal may be determined by infection status and context-dependent dispersal by the abundance of infected hosts in the population. A prerequisite for such dispersal plasticity to evolve is a genetic basis on which natural selection can act. Using interconnected microcosms, we investigated dispersal in experimental populations of the freshwater protist Paramecium caudatum in response to the bacterial parasite Holospora undulata . For a collection of 20 natural host strains, we found substantial variation in constitutive dispersal, and to a lesser degree in dispersal plasticity. First, infection tended to increase or decrease dispersal relative to uninfected controls, depending on strain identity, potentially indicative of state-dependent dispersal plasticity. Infection additionally decreased host swimming speed compared to the uninfected counterparts. Second, for certain strains, there was a weak negative association between dispersal and infection prevalence, such that uninfected hosts tended to disperse less when infection was more frequent in the population, indicating context-dependent dispersal plasticity. Future experiments may test whether the observed differences in dispersal plasticity are sufficiently strong to react to natural selection. The evolution of dispersal plasticity as a strategy to mitigate parasite effects spatially may have important implications for epidemiological dynamics.
Publisher: The Royal Society
Date: 04-01-2023
Abstract: Rapid evolutionary change during range expansions can lead to erging range core and front populations, with the emergence of dispersal syndromes (coupled responses in dispersal and life-history traits). Besides intraspecific effects, range expansions may be impacted by interspecific interactions such as parasitism. Yet, despite the potentially large impact of parasites imposing additional selective pressures on the host, their role on range expansions remains largely unexplored. Using microcosm populations of the ciliate Paramecium caudatum and its bacterial parasite Holospora undulata , we studied experimental range expansions under parasite presence or absence. We found that the interaction of range expansion and parasite treatments affected the evolution of host dispersal syndromes. Namely, front populations showed different associations of population growth parameters and swimming behaviours than core populations, indicating ergent evolution. Parasitism reshaped trait associations, with hosts evolved in the presence of the parasite exhibiting overall increased resistance and reduced dispersal. Nonetheless, when comparing infected range core and front populations, we found a positive association, suggesting joint evolution of resistance and dispersal at the front. We conclude that host–parasite interactions during range expansions can change evolutionary trajectories this in turn may feedback on the ecological dynamics of the range expansion and parasite epidemics.
Publisher: Wiley
Date: 14-02-2021
DOI: 10.1111/ELE.13692
Abstract: Exploitative parasites are predicted to evolve in highly connected populations or in expanding epidemics. However, many parasites rely on host dispersal to reach new populations, potentially causing conflict between local transmission and global spread. We performed experimental range expansions in interconnected microcosms of the protozoan Paramecium caudatum , allowing natural dispersal of hosts infected with the bacterial parasite Holospora undulata . Parasites from range front treatments facilitated host dispersal and were less virulent, but also invested less in horizontal transmission than parasites from range cores. These differences were consistent with parameter estimates derived from an epidemiological model fitted on population‐level time‐series data. Our results illustrate how dispersal selection can have profound consequences for the evolution of parasite life history and virulence. Decrypting the eco‐evolutionary processes that shape parasite 'dispersal syndromes' may be important for the management of spreading epidemics in changing environments, biological invasions or in other spatial non‐equilibrium settings.
Location: Switzerland
No related grants have been discovered for Emanuel A. Fronhofer.