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Co-evolution between mosquitoes and microsporidian transmission strategies
Auteur(s)
Maison d'édition
Neuchâtel
Date de parution
2018
Mots-clés
- Aedes aegypti
- transmission horizontale et verticale
- virulence
- évolution de l’histoire de vie
- épidémiologie
- co-évolution
- interactions hôte-parasite
- Edhazardia aedis
- Vavraia culicis
- Aedes aegypti
- horizontal and vertical transmission
- virulence
- life-history evolution
- epidemiology
- co-evolution
- host-parasite interactions
- Edhazardia aedis
- Vavraia culicis
Résumé
Hôtes et parasites s’imposent mutuellement une très forte sélection. Les premiers causent dommages et mortalité aux seconds, qui y répondent en essayant de réduire les effets négatifs, l’intensité et/ou le succès de l’infection. Les dynamiques co-évolutives qui en résultent sont profondément affectées par les conditions écologiques, qui peuvent influencer plusieurs aspects des interactions entre hôtes et parasites, comme l’évolution des traits de vie, la virulence et la transmission. En conséquence, l’incorporation et l’étude des variations de l’environnement dans le domaine de la parasitologie reste essentielle si l’on veut atteindre une compréhension exhaustive de l’évolution de l’hôte et de son parasite. Dans cette thèse, une approche expérimentale a été utilisée pour examiner l’impact des conditions écologiques et épidémiologiques sur plusieurs aspects des interactions entre un hôte et son parasite, avec une attention particulière sur les stratégies de transmission du parasite. En premier lieu, nous avons examiné l’effet de la variabilité des ressources dans l’hôte, du moment/ la chronologie de l’infection, et de la co-infection sur la virulence et le succès dans la transmission de deux parasites dotés de stratégies de transmission évolutivement en conflit. Ensuite, nous avons testé de quelle manière l’environnement et la génétique de l’hôte influencent le trade-off entre transmission verticale et horizontale dans un parasite caractérisé par la capacité d’accomplir les deux types de transmission. En élaborant une expérience évolutive, nous avons évalué si la composante verticale et horizontale de ce parasite et la virulence qui leur est associée répondent aux contraintes écologiques représentées par une disponibilité variable de ressources sur plusieurs générations. Dans une dernière expérience, nous avons investigué la présence d’une réponse plastique du taux de recombinaison de l’hôte induit par le parasite; un mécanisme qui pourrait représenter une défense intergénérationnelle de l’hôte contre une infection parasitaire. Les expériences présentes dans cette thèse couvrent plusieurs aspects des interactions entre hôtes et parasites et mettent l’accent sur le rôle des conditions écologiques dans l’évolution de ces relations. Les résultats et leurs implications sont discutés en détail tout au long de la thèse. Globalement, ce travail de thèse met en évidence la dépendance des interactions entre hôte et parasite des conditions écologiques et épidémiologiques. Réussir à séparer les différentes forces qui entourent ces interactions peut nous aider à mieux comprendre comment un environnement en constante mutation influence et détermine l’évolution des deux contendants, l’hôte et le parasite.<br><br>
<b>Abstract</b><br>Parasite and host impose strong selection on each other. The first causes damages and mortality to the host, while the second responds by reducing the detrimental effects and the intensity and/or success of infection. The resulting co-evolutionary dynamics are profoundly affected by the ecological conditions, for these may influence many aspects of host-parasite interactions including life history evolution, virulence and transmission. It is therefore essential to study and incorporate environmental variation in the field of parasitology to gain an exhaustive understanding of how host and parasite evolve.<br>
In this thesis, a single generation and an evolutionary experimental approach were used to investigate the impact of the ecological and epidemiological conditions on several aspects of host-parasite interactions, with the main focus on parasite transmission strategies. Firstly, it was examined the effect of the availability of resources for the host, timing of infection, and co-infection on the virulence and transmission success of two parasites with conflicting transmission strategy. Next, it was tested how the environment influenced the trade-off between vertical and horizontal transmission in a parasite with a mixed mode of transmission and it was assessed the genetic contribution of the host to its transmission mode. Whether the vertical and horizontal component of this parasite and the associated virulence responded to restriction opportunities, represented by different availability of resources over several generations, was investigated with an evolutionary experiment. Finally, the presence of a plastically parasite-induced response on the recombination rate of the host as a potential cross-generational defence mechanism was explored. The experiments cover many key aspects of host-parasite interactions and emphasize the role of the ecological conditions on shaping these relationships. The results and their implications are discussed in detail throughout the thesis.<br>
Overall, this work highlights the dependence of crucial aspects of host-parasite interactions from the epidemiological and ecological conditions. Disentangling the various forces surrounding these interactions may help us to acquire a better knowledge of how a changing environment may drive the evolution of both host and parasite.
<b>Abstract</b><br>Parasite and host impose strong selection on each other. The first causes damages and mortality to the host, while the second responds by reducing the detrimental effects and the intensity and/or success of infection. The resulting co-evolutionary dynamics are profoundly affected by the ecological conditions, for these may influence many aspects of host-parasite interactions including life history evolution, virulence and transmission. It is therefore essential to study and incorporate environmental variation in the field of parasitology to gain an exhaustive understanding of how host and parasite evolve.<br>
In this thesis, a single generation and an evolutionary experimental approach were used to investigate the impact of the ecological and epidemiological conditions on several aspects of host-parasite interactions, with the main focus on parasite transmission strategies. Firstly, it was examined the effect of the availability of resources for the host, timing of infection, and co-infection on the virulence and transmission success of two parasites with conflicting transmission strategy. Next, it was tested how the environment influenced the trade-off between vertical and horizontal transmission in a parasite with a mixed mode of transmission and it was assessed the genetic contribution of the host to its transmission mode. Whether the vertical and horizontal component of this parasite and the associated virulence responded to restriction opportunities, represented by different availability of resources over several generations, was investigated with an evolutionary experiment. Finally, the presence of a plastically parasite-induced response on the recombination rate of the host as a potential cross-generational defence mechanism was explored. The experiments cover many key aspects of host-parasite interactions and emphasize the role of the ecological conditions on shaping these relationships. The results and their implications are discussed in detail throughout the thesis.<br>
Overall, this work highlights the dependence of crucial aspects of host-parasite interactions from the epidemiological and ecological conditions. Disentangling the various forces surrounding these interactions may help us to acquire a better knowledge of how a changing environment may drive the evolution of both host and parasite.
Notes
, Doctorat, Université de Neuchâtel, Institut de biologie
Identifiants
Type de publication
doctoral thesis
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