Which characteristic is important for distinguishing between male and female myomorphs?

The characteristic that is most important for distinguishing between male and female myomorphs is anogenital distance. This measurement refers to the space between the anus and the genitalia, and it is significantly different between the sexes in many species of myomorphs, such as mice and rats. In males, the anogenital distance is typically greater due to the presence of the scrotum, which is positioned further away from the anus. In contrast, females have a shorter distance as their genital opening is located closer to the anus. This anatomical feature is a reliable indicator of sex, especially in young individuals where other characteristics, like size or weight, may not be fully developed or may overlap between sexes.

Eye color, size, and weight can exhibit considerable variation based on individual genetics, environmental factors, and age, making them less reliable for determining sex in myomorphs. Therefore, anogenital distance serves as a clear and consistent method for sex identification in these animals.