Thèse soutenue

Etude théorique des conséquences démographiques et évolutives des processus s'exprimant à faible densité dans les systèmes hote-parasitoide
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Auteur / Autrice : Laure Bompard
Direction : Minus van Baalen
Type : Thèse de doctorat
Discipline(s) : Frontières du vivant
Date : Soutenance en 2014
Etablissement(s) : Paris 7

Mots clés

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Résumé

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In low-density populations, genetic diversity is decreased and mate-finding is increasingly difficult, two phenomena that may induce extinctions if the demography is simple. During my thesis, I used mathematical modeling to investigate the impact of such phenomena on parasitoids in which population dynamics are more complex (due to the close interaction between the parasitoid and its host. The study of the fate of small parasitoid populations is particularly justified in the context of biological control, in which parasitoids are widely used and often introduced in low densities. This manuscript is built on scientific papers and organized into three parts: i) a literature synthesis; ii) the theoretical impact of mate-finding Allee effect on the demography of parasitoids and iii) the theoretical impact of Complementary Sex Determination (CSD), which induces a genetic load specific to the Hymenoptera, on the demography of parasitoids on the evolution of mate-choice to avoid the deleterious consequences of this burden at the individual level. I conclude that considering the presence of an interspecific interaction, such as the host-parasitoid interaction, is crucial to predict the consequences of Allee effects and genetic load. We show that parasitoid survival can be very sensitive to mate-finding Allee effects, depending on the host dynamics. We also show that contrary to what has been described in non parasitoid populations, CSD does not induce an extinction vortex in parasitoids, but on the contrary limits their extinction risk. This highly innovative result provides a new look at the demographic and evolutionary consequences of genetic load in interacting populations.