Host plant selection in closely related butterfly species due to reproductive interference: Modelling a tritrophic system
Sammanfattning: Host plant selection is an important process during the life cycle of lepidopterans, providing ovipositing sites for adults and food resources for the larvae. The processes behind host plant selection have been extensively studied, especially in closely related species in the context of niche separation. Empirical and theoretical studies have shown that multiple processes, such as resource competition, parasitoid avoidance and reproductive interference between interspecific individuals can affect host plant selection, often leading to niche separation. The aim of this study was to create and analyze a mathematical model using the adaptive dynamics techniques, in order to study the evolution of habitat selection. Our model incorporated three processes: Resource competition in the form of density dependent growth, parasitoid attacks and repro- ductive interference in a two species-two habitat system. It was hypothesized that the presence of parasitoids would promote co-existence through top-down control, while reproductive inter- ference would promote niche separation. The results confirmed both hypotheses. The analysis incorporating only the effect of parasitism showed the evolution of habitat separation when parasitoids attacked randomly and the evolution of co-existence in both habitats in the case of switching parasitoids. On the other hand, incorporating reproductive interference promoted the evolution of partial or complete niche separation. The extent of this process was shown to depend on the strength of reproductive interference and the initial habitat choice of the two species. Stronger reproductive interference increased the size of the set of initial conditions leading to the evolution of complete niche separation. The analysis conducted in this study demonstrated the opposing effects of parasitism and reproductive interference on the evolution of habitat selection, promoting co-existence and separation respectively.
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