Revisiting the influence of learning in predator functional response,
how it can lead to shapes different from type III.
Abstract
Abstract Predator/Parasitoid functional response is one of the main
tools used to study predation behaviour, and in assessing the potential
of biological control candidates. It is generally accepted that predator
learning in prey searching and manipulation can produce the appearance
of type III functional response. Holling proposed that in the presence
of alternative prey, at some point the predator would shift the
preferred prey, leading to the appearance of a sigmoid function that
characterized that functional response. This is supported by the analogy
between enzyme kinetics and functional response that Holling used as the
basis for developing this theory. However, after several decades,
sigmoidal functional responses appear in the absence of alternative prey
in most of the biological taxa studied. Here, we propose modelling the
effect of learning on the functional response by using the explicit
incorporation of learning curves in the parameters of the Holling
functional response, the attack rate (a), and the manipulation time (h).
We then study how the variation in the parameters of the learning curves
causes variations in the shape of the functional response curve. We
found that the functional response product of learning can be either
type I, II or III, depending on what parameters act on the organism, and
how much it can learn throughout the length of the study. Therefore the
presence of other types of curves should not be automatically associated
with the absence of learning. These results are important from an
ecological point of view because when type III functional response is
associated with learning, it is generally accepted that it can operate
as a stabilizing factor in population dynamics. Our results, to the
contrary, suggest that depending on how it acts, it may even be
destabilizing by generating the appearance of functional responses close
to type I.