A model for the entropy change in generations in the process of segregation and recombination of two pairs of heterogenes in linkage were constructed by discrete linear system,presenting a relationship between the entropy and the crossoverate.The percentage of the monogenic hybrid increased from F1 to F2,and then decreased and tended to 0 finally.The percentages of the four homozygotic types eventually in the population were related to the crossoverate.In this paper,it was found that the change laws were no...