Theory 67/Ecosystem/Trophic cascades
Cascades Need Ranges to Overlap
The claim
The strength of a trophic cascade is set by the ratio of predator range to prey range, so a wide-ranging predator produces a weaker cascade than a resident one.
01Mechanism
Control requires the predator to be present where the prey is dense; the overlap determines how much of the prey population is exposed.
02Prediction
Cascade strength should track the range ratio.
03Refutation
Cascade strength tracking predator abundance would remove the spatial term.