Abstract
A well-accepted narrative in ecology is that prey modify traits to reduce
predation risk, and the trait modification has costs large enough to cause
ensuing demographic, trophic and ecosystem consequences, with implications
for conservation, management, and agriculture. But ecology has a long
history of emphasizing that quantifying the importance of an ecological
process ultimately requires evidence linking a process to unmanipulated
field patterns. We suspected that such process-linked-to pattern (PLP)
studies were poorly represented in the predation risk literature, which
conflicts with the confidence often given to the importance of risk
effects. We reviewed 29 years of the ecological literature which revealed
that there are well over 4000 articles on risk effects. Of those, 349
studies examined risk effects on prey fitness measures or abundance (i.e.,
non-consumptive effects) of which only 26 were PLP studies, while 275
studies examined effects on other interacting species (i.e., trait
mediated indirect effects) of which only 35 were PLP studies. PLP studies
were narrowly focused taxonomically and included only 3 that examined risk
effects on unmanipulated patterns of prey abundance. Before asserting that
risk effects drive ecological community dynamics, more attention must be
given to examining whether risk-effect processes influence unmanipulated
field patterns across diverse ecosystems.