THE Cricetomys gambianus or African giant rats fascinate with their intelligence. These big rodents are so smart that they have, on several occasions, helped save lives. Some have been specially trained defusing landmines or sniffing out tuberculosis. Others have learned to carry small backpacks to rescue people in disaster areas.
Unfortunately, these intelligent mammals are not prolific. Breeders are desperate to get more breeding females because the supply is not enough to meet the demand. And yet, other rodents are renowned for their ability to multiply wildly.
Intrigued, Alex Ophir, behavioral ecologist, leaned over the reproductive behavior of this species in 2019.
Female giant rats seal their vaginas to stop breeding
In reality, the Cricetomys gambianus East closer to the hamster than to the rat. This animal, regarding a meter long from the whiskers to the end of the tail, can live up to eight years. However, much to the surprise of breeders, many females do not breed until they are four years old. Worse still, some of them stop following a successful pregnancy.
Baffled by this phenomenon, researchers have taken a closer look. They discovered that many females had not only renounced having other children, but that they had literally closed their vaginas. Scientists believe it is a hormonal manipulation of dominant females so that the others, once sterilized, take care of them.
Nonbreeders reopen their vaginas when the dominant dies
Significant changes are occurring in Cricetomys females that have stopped reproducing. In this particular morphological state, their uterus have shrunk and their vaginal opening has fused together. In addition, the chemical composition of their urine is different from that of their actively breeding conspecifics. The researchers also noticed that this phenomenon is reversible.
Ethologist Angela Freeman and her colleagues at Cornell University counted no less than 23 transitions in 17 female rats. Also, when one of the active breeding females has died of old age, the vagina of the other members of the colony has opened. Recall that other mammals also have a reproduction modulated by hormones, such as those whose reproduction is seasonal.
SOURCE : SCIENCEALERT
