A Study of the Dynamics of a Population of Pero- myscus gossypinus and P. nuttalli Su6jected to the Effects of X-lrradiation

A large number of experiments have been conducted in recent years that have demonstrated the deleterious effects of ionizing radiation in both individuals and in populations. It is a well established fact that if radiation is delivered to the gonads, inheritable changes will occur in the germ cells. The net effect of these changes is to increase the genetic variability of a Mendelian population, if the irradiated individuals are allowed to breed with other individuals in the population. The present paper is a report of the effects of x-irradiation on a natural population of two species of wild mice; the cotton mouse (Peromyscus gossypinus) and the golden mouse (Peromyscus nuttalli). Studies on the dynamics of any natural population are important because the individuals that make up such a population are the basic units by which gene exchange is effected (Blair, 1953). It is generally recognized and accepted that any population of sexually reproducing organisms represents a gene pool from which the various combinations of genes that are best suited to a particular environment are chosen through the process of natural selection. The present study was designed to analyze the effects of a presumed increase in genetic variation in mouse populations which were already well adapted to the environment in which they were living. It was expected that, in this case, the effects of x-irradiation would be revealed by a study of the dynamics of the two species populations as well as in the customary more easily measured morphological form. This work was made possible by a grant from the U. S. Atomic