RIVERSIDE, Calif. The direct effect predators have on their prey
is to kill them. The evolutionary changes that can result from
this direct effect include prey that are younger at maturity and
that produce more offspring. But killing prey also has indirect
effects rarely characterized or measured such as a decline in
the number of surviving prey, resulting, in turn, in more food
available to survivors. In a new study characterizing the
complex ecological interactions that shape how organisms evolve,
UC Riverside biologists Matthew Walsh and David Reznick present
a novel way of quantifying these indirect effects by showing
that prey adapt to food availability as well as the presence of
predators. Our study can serve as a model for how humans alter
ecosystems when they remove key predators like wolves and bears
from land or tuna and billfish from seas, said Reznick, a
professor of biology. He and Walsh compared life history traits
between Trinidadian fish communities impacted by the presence of
predators. They