Host–parasite interactions in food webs: Diversity, stability, and coevolution

Food web theory is increasing in importance, along with the decline in biodiversity and ecosystem functioning observed currently. Recently, parasites have been included in several well-characterised food web models based on natural systems of the biosphere, however the reception of this work by ecologists has been mixed. Here we review the contemporary concepts of ‘food web’ and ‘parasite’ and attempt to summarise why the inclusion of parasites in food webs has been an issue so frequently mired in difficulties. The review also outlines several areas of recent research that highlight the importance of the host–parasite relationship in ecological networks, and how understanding this relationship is crucial to attaining accurate ecological simulations of natural systems. Finally, we bring coevolutionary theory forward as a missing dynamic in food web models, especially those that include parasites. We emphasise the prevalence of parasitism and its irrefutable place in food web theory.