The ontogeny of food web structure

Background/Question/Methods

Food web theory has seen a resurgence in recent years, with particular emphasis on developing a better understanding of the spatiotemporal dynamics of webs. Still, the large amount of detailed information needed for web analyses has resulted in especially few spatiotemporally well-resolved datasets, making it difficult to evaluate current models and develop new ones. To remedy this, we established a well-replicated spatial array of artificial ponds in the field and tracked their assembly through time. We constructed food web time-series using a combination of gut content analyses, field observations, and information in the literature, and generated biomass flow networks using a network reconstruction algorithm. We then explored the dynamics of food web properties as a function of time and distance from the colonization source.

Results/Conclusions

Distance had a significant effect on the timing and trajectory of food web assembly. Webs exhibited a transition from loose affiliations of species early in assembly to more coherent, rigid, and organized networks through time. Distance altered the timing of this transition such that food webs “assembled” fastest near colonization sources and slowest in isolation. Further, isolated webs exhibited a significantly less well-connected network topology by the experiment’s conclusion. Overall, these results stress the importance of considering spatial and temporal scale when constructing and analyzing real food webs.