GENETIC-STUDIES OF ASSORTATIVE MATING - A SIMULATION STUDY .1. CHARACTERISTICS OF THE CONTROL POPULATIONS

Design of control populations to be used in the simulation studies of assortative mating is discussed. In order to be useful for 25 generati ons a control population should satisfy the following requirements: (i ) phenotypic correlation of mates, r(p), close to zero; (ii) negligibl e amount of random drift; and (iii) large number of loci controlling t he trait under consideration. It was concluded that under the assumpti ons of the design used in the present study the number of animals to p roduce a negligible amount of random drift (200 mating pairs) is much smaller than the number of animals necessary for r(p), to be sufficien tly close to zero to exclude unconscious assortative mating (400 matin g pairs). The minimum number of loci required allowing the trait to sh ow a sufficiently large amount of genetic variation even in long-term selection studies depends, among other things, on the selection intens ity and the number of generations involved. In more intensely selected populations more loci are required. In long-term selection experiment s with 25 generations and 25% selected, the number of loci required, e ach with a very small equal effect, was 2500. An unselected control po pulation fulfilling these requirements behaves similarly to the predic tions of both the Hardy-Weinberg model and the infinitesimal model. (C ) 1997 Scandinavian University Press.