arXiv subjects

Ana T. C. Silva

Publications and source records attributed to Ana T. C. Silva.

3 recordsLinked to original sources

arXiv2024

Why aphids are not pests in cacao? An approach based on a predator-prey model with aging

We studied a mean-field predator-prey model with aging to simulate the \mbox{interaction} between aphids (\textit{Toxoptera aurantii}) and syrphid larvae in \mbox{cacao} farms in Ilheus, Bahia. Based on the classical predator-prey model, we \mbox{propose} a system of differential equations with three rate equations. \mbox{Unlike} the original Lotka-Volterra model, our model includes two aphid population classes: juveniles (non-breeding) and adult females (asexually breeding). We obtained steady-state solutions for juvenile and adult populations by \mbox{analyzing} the stability of the fixed points as a function of model \mbox{parameters}. The results show that the absorbing state (zero prey population) is always possible, but not consistently stable. A nonzero stationary solution is achievable with appropriate parameter values. Using phase diagrams, we analyzed the \mbox{stationary} solution, providing a comprehensive understanding of the \mbox{dynamics} involved. Simulations on complete graphs yielded \mbox{results} closely matching the differential equations. We also \mbox{performed} simulations on \mbox{random} networks to highlight the influence of \mbox{network} topology on \mbox{system} behavior. Our findings highlight the critical role of life-stage structure, \mbox{predation}, and spatial variation in stabilizing predator-prey \mbox{systems}. This emphasizes the importance of network effects in population dynamics and refines the framework for biological pest control in agriculture. Ultimately, our research contributes to sustainable agricultural practices.

q-bio.PE↗

arXiv2005

Effect of Predators of Juvenile Rodents on the Spread of the Hantavirus Epidemic

Effects of predators of juvenile mice on the spread of the Hantavirus are analyzed in the context of a recently proposed model. Two critical values of the predation probability are identified. When the smaller of them is exceeded, the hantavirus infection vanishes without extinguishing the mice population. When the larger is exceeded, the entire mice population vanishes. These results suggest the possibility of control of the spread of the epidemic by introducing predators in areas of mice colonies in a suitable way so that such control does not kill all the mice but lowers the epidemic spread.

q-bio.PE↗

arXiv1999

Stochastic group selection model for the evolution of altruism

We study numerically and analytically a stochastic group selection model in which a population of asexually reproducing individuals, each of which can be either altruist or non-altruist, is subdivided into $M$ reproductively isolated groups (demes) of size $N$. The cost associated with being altruistic is modelled by assigning the fitness $1- τ$, with $τ\in [0,1]$, to the altruists and the fitness 1 to the non-altruists. In the case that the altruistic disadvantage $τ$ is not too large, we show that the finite $M$ fluctuations are small and practically do not alter the deterministic results obtained for $M \to \infty$. However, for large $τ$ these fluctuations greatly increase the instability of the altruistic demes to mutations. These results may be relevant to the dynamics of parasite-host systems and, in particular, to explain the importance of mutation in the evolution of parasite virulence.

adap-org↗