Anteater Virgin Birth Mystery Solved: What is Embryonic Diapause?
The mystery of the Connecticut "anteater virgin birth" may be solved.
For those who haven't followed what may be the most interesting news to have ever come out of Greenwich, Conn., here's a brief recap:
A few weeks ago, an anteater named Armani was born at the LEO Zoological Conservation Center to a lady anteater named Alice. This was an unusual birth -- some were calling it an immaculate conception -- because Alice had not been with a male partner in 18 months. Anteaters have a six-month gestation period, so Alice's handlers really weren't sure how she came to be pregnant with no recent male contact.
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Officials at the Connecticut Conservation Center now say they believe it was a case of embryonic diapause.
With embryonic diapause, an animal's egg is fertilized, but it more or less stops growing if environmental conditions aren't right. The embryo does not implant in the uterus, as would normally be the case, but stays in a dormant state. During this time, little development of the embryo occurs, and it does not attach to the uterine wall. The gestation period is elongated.
So in the case of Archie the anteater, although 18 months had elapsed since Alice got together with Alf, her last male partner, the embryo could have been in a dormant state in her uterus.
The phenomenon has been documented in less than 2 percent of all mammals. It has never been observed before in anteaters -- and this may not in fact be a case of embryonic diapause -- but there have been cases of armadillos, which are closely related to anteaters, undergoing embryonic diapause. And one 2012 paper published in PLoS ONE suggested that all mammals are capable of embryonic diapause.
Of the 100 or so animals that have been documented undergoing embryonic diapause, one of the more interesting cases is the giant panda, as it appears to be somewhat common in the species. According to the San Diego Zoo, their panda Bai Yun has had pregnancies that spanned between 101 to 150 days. A normal gestation period for a panda fetus is thought to be about 50 days. Pandas are notoriously difficult to breed, and according to Suzanne Hall, the senior research technician for the San Diego Zoo Institute for Conservation Research, embryonic dispause makes it even trickier, because the panda handlers are not really sure if a panda is delaying implantation, or if she is simply not pregnant at all.
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