Incorporating demographic diversity into food web models: Effects on community structure and dynamics
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© 2015 Elsevier B.V. Life history strategies affect population dynamics; however, their effects on community dynamics remain poorly understood. A food web model with stage-structured populations (structured food web) and an equivalent model with unstructured populations (unstructured food web) were developed, and their structures and dynamics were compared. Both models incorporated energetic processes and allowed populations to go extinct and invade over time. The results from the two models shared some similarities. For example, all of the initial randomly formed food webs were unstable, but the extinction and invasion rates of populations declined over time. However, there were also clear differences between them. For example, preventing trophic interactions among similar-sized organisms led to a large increase in the number of persisting consumer populations under the unstructured food web, but the number was almost unchanged under the structured food web. Furthermore, an increase in the carrying capacity of primary producers caused an increase in the population extinction rate of consumers under the structured food web, but the extinction rate declined under the unstructured food web. Finally, the average trophic level of consumers in the unstructured food web was often at 2, indicating the food web primarily consisted of herbivores. On the other hand, the average trophic level in the structured food web was significantly higher, indicating the existence of trophic interactions among consumers. These results suggest the importance of incorporating stage structures into food web models to bridge the current theories of food web dynamics and empirical observations because nature consists of structured populations. In particular, I conclude that if one wants to study trophic interactions beyond herbivory, it is crucial to incorporate structured populations into food web models.
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