Selection for an Invariant Character, Vibrissa Number, in the House Mouse II. Limits to Variability

Abstract

A selection experiment for vibrissa number in tabby mice has been extended for 13 generations. Progress of selection for the first seven generations has already been reported. The results of the next six generations of selection are given and the whole experiment is considered with regard to (1) the shapes of the frequency distributions for the three genotypes (+, Ta+, and Ta·) for succeeding generations; (2) limits to phenotypic variation, i.e. canalization mechanisms; and (3) reproductive fitness.