Benefits of a Model of Segregation for the Understanding of Chromosomal Evolution

Abstract

We propose a model for the meiotic segregation of translocated chromosmoes based on the definition of stable orientations for the meiotic configurations. The model stipulates that only stable orientations of a meiotic configuration are followed by the segregation of chromosomes whereas configurations with unstable orientation undergo reorientation. We apply a method of chiasma distribution estimation based upon crossover frequencies observed in family data in order to estimate, for a given translocation, the distribution of the different meiotic configurations. Together with the segregation model, this method allows the prediction of the gametic distribution of the different chromosomal constitutions and in particular the relative proportion of unbalanced gametes. This segregation model should be of inteterest for the understanding of chromosome evolution since it provides a measure of the selective disadvantage associated with a chromosome rearrangement.