Biotic and abiotic effects of the community on thefunctionality and structure of a host-parasitoid multitrophic food web in the long term

Abstract

Every food web has structural metrics in common, where metaphorically can be considered as a “map” that shows the species location however, the location of them is not so clear because the species are linked by feeding links that can be breakable or flexible due to the intensity of the interaction between them in the web, which can compromise the stability and complexity of the web through the functional composition between trophic levels. Understanding how each species respond to variations in the environment driven by biotic and abiotic factors in the long term is relevant for studying the diversity function of species in the ecosystem. However, the potential ramifications of wider changes to food webs on host-parasitoid interactions through both direct and indirect interactions that are affected are wide-ranging but poorly documented, mainly regarding trophic level functionality, structure, stability, and complexity. In this thesis, questions about functional dynamics and their relationship with the environment and the trophic network were addressed. Manuscript 1, was investigated whether the functional composition of the trophic levels that are correlated with the structure, complexity, and stability of the food web. Manuscript 2, was explored the relationship of species functionality with biotic and abiotic factors. In both manuscripts, was used a dataset for the long term of the five years about the host-parasitoid food web hosted by Senegalia tenuifolia. The results of manuscript 1, showed that the structure, complexity, and stability of the food web are correlated to herbivory, parasitism, and hyperparasitism rate, especially the highest trophic level. In manuscript 2, was found that temperature and precipitation act differently on herbivory and parasitism rates, and above all, there is a combination of abiotic and biotic factors that drive the species functionality. Taken together the results from both chapters give us the idea that the functional diversity and structure of the network are correlated to ensure its stability and complexity, in which the functional composition of the trophic levels is driven by the synergy between biotic and abiotic. The main implications found in the context of the functioning of the ecosystem are discussed at the end of the thesis.