Multi-trophic diversity maintenance
We did not invent the multitrophic diversity maintenance idea, but we have been developing concepts within it. Fundamentally, the way we look at it, the whole foodweb is potentially involved in maintenance of diversity within any ecological guild of species within the foodweb. We explain all this in Chesson and Kuang (2008), and Kuang and Chesson (2009), for a start. These developments produce some concepts that are our coinage: competition-based and predation-based mechanisms. For competition-based mechanisms, species coexist because intraspecific competition is stronger than interspecific competition. For predation-based mechanisms, species coexist because intraspecific apparent competition is stronger than interspecific apparent competition.
Chesson, P, and Kuang, J.J. 2008. The interaction between predation and competition. Nature 456, 235-238.
Kuang, J.J. and Chesson, P. 2009. Coexistence of annual plants: generalist seed predation weakens the storage effect. Ecology 90, 170-182