Table 2.

Conditions often present during cascading speciation as outlined in Abrahamson & Blair [4], Hood et al. [8] and Brodersen et al. [3], and available evidence for those conditions in the ponderosa pine–western pine beetle–symbiotic fungi system.

condition	generalization for upward adaptive radiation cascade in a predator–prey system [3]	evidence in the ponderosa pine–western pine beetle–symbiotic fungi system
1	ecological speciation and ecotype formation in prey involves a shift to a new habitat or resource and genetic differentiation	[27,33]
2	species or ecotypes of prey as well as individual predators exhibit habitat preferences	[34,47]
3	predators have distinct preferences among alternative prey	unclear but likely [34,47]
4	predator–prey phenology match or overlap sufficiently	n.a.
5	significant predator trait × prey type interactions determine fitness variation among predators	[16]
6	mate choice among predators is mediated by habitat or is affected by feeding related behavioural, ecological or morphological traits	[47,48]
7	Populations of prey and predators at least partly overlap in their geographical ranges	n.a.
8	ecological diversification among predators is at least to some degree associated with genetic differentiation	([19,27,33], present study)