Fertility and Size Inheritance in a Peromyscus Species Cross

The North American cricetid genus Peromyscus has long been recognized as a useful group for evolutionary and genetic studies The diversity of species and subgeneric taxa Dice (1940) concluded from hybridization studies that within the genus there exists a spectrum of genetic isolation, ranging from complete fertility between most races of the same species, through several grades of partial isolation between species of the same species group, to complete intersterility among species of different species groups or subgenera.