Population Dynamics Of Two-Sex Models

Due to some reasons, the physiology characteristics of two sex subpopulations of some populations are different. These characteristics mainly are death rate, birth rate, the ability of competing for food and of avoiding being predated, etc. They may cause alterations of the numbers of two sex subpopulations and of sex ration (the ratio of number of female subpopulation to that of male subpopulation). However, appropriate sex ratio is very important for population to develop. Therefore, it is of much importance in theory and practice to study two-sex models.In the second chapter, a model similar to Malthus analogy is introduced, which supports an exponential solution which is globally asymptotically stable; however, the sex ratio is stable. In the third chapter we propose a density-restricting two-sex model based on the one in the second chapter and obtain the proportion of birth rates and death rates when the survival ability is most strong, which shows that the two-sex birth rate is not best when it is 1 : 1. In addition, the sex ratio is stable.In the forth chapter we propose a predator-prey model with sex difference in prey population. It is shown that the predation of prey which is not sex-biased will not alter the proportion of male prey to female prey though the number of prey population changes periodically. However, sex-biased predation can alter it.In the fifth chapter a competitive two-sex model is proposed with sex difference only in the first population. If the two competitive coefficients of the second population to female and male subpopulations of the first population are equal then the ratio of the first population is a constant which does not depend on competitive parameters. Computer...