Upscaling of pairwise trophic interactions to food web structure in marram grass dunes
Logghe, G. (2020). Upscaling of pairwise trophic interactions to food web structure in marram grass dunes. MSc Thesis. Universiteit Antwerpen: Antwerpen. 44 pp.
Food webs are widely used as a tool to describe and study the feeding links between species within an ecosystem. In many cases, the construction of these networks is based on the body size ratios of all considered species. This approach is derived from the assumption that predators are usually larger than their prey, as it is expected that it becomes increasingly difficult to handle larger prey items. However, sufficient experimental evidence to support this hypothesis is still lacking. Therefore, the present study employed an innovative experimental approach to assess whether the theory holds true for arthropod communities in marram grass dunes. This method consisted of collecting several arthropod species along the Belgian coast and observing their interactions with each other. Before the start of each pairwise trial, the length of both combatants was recorded to enable the outcome of the experiment to be linked to the body size ratios of the interacting species. Additionally, the results of all trials were used to construct a more realistic food web for marram grass dunes and compare this to a theoretical description of such a food web based on body size ratios and expert knowledge. This way, the reliability of size-based construction of food webs for assessing network topology could be validated. Furthermore, the effect of habitat structure on predator-prey interactions and the relationship between body length and the time until predation were assessed. The results of this study support the hypothesis that predators are generally larger than their prey and mostly fit the theoretical food web based on body size ratios. However, it was observed that other species characteristics exert their influence on the outcome of trials, indicating that body size is by no means the only relevant trait for explaining trophic interactions.
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