One Kind Of Predator-Prey Model Based On Penna Model

Penna T J P proposed a model in 1995 using 0-1 Bit-String to represent genome of individuals. The model is about organic evolution of a single species and studies the population's dynamical evolution by computer. Since Penna model was proposed, it is often used used to illustrate some realities, and used to elaborate the meaning behind the model's development and application. The method, which studies the whole population's development from the respect of the individual using Penna model and a two-dimension lattice is very effective.In the first chapter we describe the content of Penna model simply and give out its results, in chapterâ…¡andâ…¢, based on Penna models and two-dimension lattice, we have studied the population's evolution in the Predator-Prey model. The two parts are my own work.In the chapterâ…¡, we apply Penna model on a two-dimension lattice in the Predator-Prey model(there are three groups of grass, sheep and wolf), and have studied that the amount of grass has a direct impact on the population of sheep and wolf:if grass is sufficient, the three groups can have a good coexistence; otherwise, groups may become extinct.In chapterâ…¢, on the basis of sufficient grass, and we endow the sheep escaping capability and the wolf predation capability, with two Gauss functions simulating them. Firstly, we simulate the model's dynamical evolution when the wolf's predation capability respectively gets two different values, and find that sheep are not always able to live with wolves as the two groups'coexistence depends on the sheep's escaping capability and the wolf's predation capability. Then, we study how escaping capability and predation capability impact the evolution. Whether the two groups can coexist is firstly decided by the sheep's escaping capacity:if sheep's escaping capacity is too weak, at early time of the evolution, with very high rate of successful in wolves'predations, a large number of sheep are preyed, then the sheep's population drops sharply, and the wolf's group gets extinct drastically because of deficiency on food. Because the wolf's predation is randomly, there are always sheep alive. After the extinction of wolf, the population of sheep will flourish and finally become stable. Furthermore, when sheep's escaping capability is fixed, wolfs predation capability has a direct impact on the two groups:whether it too strong or too weak is not conductive to two species'symbiosis. If the predation capability is too strong, lots of sheep are dead because of being preyed on. At the same time, as there are few sheep for wolves to eat, lots of wolves die because of hunger, ultimately the whole group becomes extinct; if the wolf's predation capability is too weak, during the whole evolution, the individuals of wolf which can get food successfully are always very few, while a large number of individuals will die because they can not obtain food successfully for energy supplying, afterwards, the wolf gets extinct. In addition, after some analysis we find when the model's parameters are respectively set to the values around sexual maturity of the two groups, the escaping capacity and predation capability both are very strong and conducive to two species'symbiotic.