|
Abstract:
|
It has been reported that, in order to reduce mortality, prey are able to change their phenotype
in response to cues released from predators. These short-time responses constitute
effective antipredator strategies in variable environments, and involve changes in morphology,
behavior, physiology or life-history traits of prey individuals belonging to a wide spectrum
of taxa. Defenses can be classified into pre-encounter and post-encounter, depending
on the phase of the predation process in which they take place. Also, inducible defenses
should be costly.
Despite the current knowledge of inducible defenses at the individual level, our understanding
of their dynamic consequences at the population and community level is limited.
In this work we construct and analyze numerically a predator–prey system, parameterized
from published experimental data, in which prey exhibit inducible defenses of the type preencounter
(affecting attack rate) or post-encounter (affecting handling time) and entailing
either metabolic or feeding costs. The above assumptions were analyzed over a gradient of
resource availability.
Our results indicated that both types of cost have a similar effect on the dynamics of
the model system, but we expect that different costs will produce different outcomes in a
more complex model community. Conversely, pre-encounter and post-encounter IDs define
domains of attraction with different size and shape within the studied sections of themultidimensional
parameter space. Roughly speaking, post-encounter IDs determine a more rich
dynamics when plausible parameter values are chosen, and the effect of resource density
is different if the ID is handling-time based or attack-rate based. In agreement with previous
works, our analyses indicate that IDs can damp population oscillations and prevent the
paradox of enrichment. |