Libro de Resúmenes / Book of Abstracts (Español/English)

Resumenes 87
An important part of a population’s environment is the presence of
populations of different species with which the first coexists. This implies
that evolutionary changes in a species may lead to evolution in another
species with which it interacts. When such changes occur reciprocally
between two species, there is coevolution. This work evaluates coevolution
in a predator-prey system given by a Lotka-Volterra model, whose
parameters are functions of individual traits and are subject to modification
by natural selection. Both species are supposed to dedicate all their energy
to survival, reproduction and producing traits that intensify or attenuate
predation pressure. The prey’s net energy is constant, while the predator’s
depends on the prey capture rate, which requires investment. This tradeoff
affords the link for evaluating the coevolution of life histories between
predator and prey. The model intends to answer, using the Theory of
Evolutionary Games, how the investment in predation-related traits in one
of the antagonists influences the evolutionary stable strategy of energy
allocation among traits of the life history of the other species when only one
is subject to evolution, and whether the evolutionary dynamics differs when
considering coevolution.
Results indicate that when only one of the antagonists’ evolution is
considered, each of them reaches the Evolutionary Stable Strategy. In the
prey, investment in defence is directly proportional to investment in attackrelated
traits in the predator, while this last desists when the prey increases
its defences. The equilibrium point in this system is unstable, because
evolution in the prey causes the dynamics to move away from the
equilibrium point, while evolution in the predator causes it to move towards
it, producing an evolutionary saddle. When the possibility of simultaneous
adaptations is considered, the equilibrium point remains unstable, but
evolutionary variables show a stable cyclic behaviour which is continued
indefinitely, leading to a Red Queen dynamics. Thus, the effect of
coevolution in this system is stabilizing.
Feedback between the predator’s energy budget and that of the
prey’s, which constitutes the original trait of the model, is the supposition
which allows the stabilizing effect of the predator’s evolution, responsible
for the instability of the equilibrium point and, therefore, of the oscillation of
the evolutionary traits in a limit cycle.