Looking forwards and backwards in a bisexual Moran model

In this paper a bisexual Moran model is introduced. The population consists of N pairs of individuals. At times t=1,2,...two individuals are born, who ‘choose their parents randomly’ and independently of each other. Then one of the pairs is removed and replaced by the two individuals born at that instant. The extinction probability of the descendants of a single pair and the number of ancestors of a whole generation are studied. A limit result for large population sizes has been derived by diffusion approximation methods.