Female snake living in captivity without a male companion gives birth – again

For the second time in two years, a female yellow-bellied water snake in Missouri reproduced on her own, a rare occurence called parthenogenesis

Associated Press in St Louis

Thursday 17 September 2015 18.57 BSTLast modified on Thursday 17 September 201519.10 BST

For the second time in two years, a captive snake in south-east Missouri has given birth without any interaction with a member of the opposite sex.

Officials at the Missouri department of conservation’s Cape Girardeau Conservation Nature Center say a female yellow-bellied water snake reproduced on her own in 2014 and again this summer. The snake has been living in captivity, without a male companion, for nearly eight years. An intern who cares for the snake found the freshly laid membranes in July.

This year’s offspring didn’t survive, but the two born last summer are on display at the nature center, about 100 miles south of St Louis.

Conservation Department herpetologist Jeff Briggler said virgin births are rare but can occur in some species through a process called parthenogenesis. It occurs in some insects, fish, amphibians, birds and reptiles, including some snakes, but not mammals.

Parthenogenesis is a type of asexual reproduction in which offspring develop from unfertilized eggs, meaning there is no genetic contribution by a male. It’s caused when cells known as polar bodies, which are produced with an animal’s egg and usually die, behave like sperm and fuse with the egg, triggering cell division.

Love and other animals

For the female whiptail lizard, finding a mate can be impossible. Though she has all the right skills and equipment for a successful courtship – head bobs, mouth displays, attractive colouring – they do her little good. She tastes the air for male pheromones by flicking her forked tongue while scouring the barren landscape of the Sonoran Desert. The male population is so small, however, that there is almost no chance she will find any – making the female whiptail lizard the ultimate loner of the animal kingdom. Maybe there have been times in your life when you felt just as lonely as a whiptail.

The desire to couple up, settle down and have children can be stifling. We are constantly reminded that nobody stays young or beautiful forever and that all the good ones are getting away. Who, at times, wouldn't feel desperate? Countless nights alone give rise to feelings of inadequacy, and so we rake internet dating sites in search of that special someone , filling up our schedules with dinners that seem to go nowhere.

You ask your friends to try and to set you up, but connecting is tough and you begin to feel like there is nobody out there for you. Despite the great life you may have built, you begin to measure yourself not by what you are doing but by whom you are doing it with. The seemingly endless search for a significant other leaves you feeling utterly insignificant, and you wonder how whiptails survive at all.

When the whiptail lizard cannot find a mate, she relies on herself, even for reproduction. Using parthenogenesis, she produces clones of herself. She will build a nest, lay her eggs, and her tiny duplicates will hatch two to three months later. Females have been reproducing this way for so long that male populations have nearly been wiped out. Over millions of years of evolution, perhaps the lizard has discovered that the only one worth caring for is herself.

Continued:  http://www.guardian.co.uk/lifeandstyle/2012/jun/10/love-animals-loneliness-whiptail-lizard

Boa Constrictors Can Have Babies Without Mating, New Evidence Shows

ScienceDaily (Nov. 4, 2010) — In a finding that upends decades of scientific theory on reptile reproduction, researchers at North Carolina State University have discovered that female boa constrictors can squeeze out babies without mating.


More strikingly, the finding shows that the babies produced from this asexual reproduction have attributes previously believed to be impossible.


Large litters of all-female babies produced by the "super mom" boa constrictor show absolutely no male influence -- no genetic fingerprint that a male was involved in the reproductive process. All the female babies also retained their mother's rare recessive color mutation.

This is the first time asexual reproduction, known in the scientific world as parthenogenesis, has been attributed to boa constrictors, says Dr. Warren Booth, an NC State postdoctoral researcher in entomology and the lead author of a paper describing the study. He adds that the results may force scientists to re-examine reptile reproduction, especially among more primitive snake species like boa constrictors.

The study is published online in Biology Letters, a Royal Society journal.

Snake sex chromosomes are a bit different from those in mammals -- male snakes' cells have two Z chromosomes, while female snakes' cells have a Z and a W chromosome. Yet in the study, all the female babies produced by asexual reproduction had WW chromosomes, a phenomenon Booth says had not been seen before and was believed to be impossible. Only through complex manipulation in lab settings could such WW females be produced -- and even then only in fish and amphibians, Booth says.

Adding to the oddity is the fact that within two years, the same boa mother produced not one, but two different snake broods of all-female, WW-chromosome babies that had the mother's rare color mutation. One brood contained 12 babies and the second contained 10 babies. And it wasn't because she lacked options: Male snakes were present and courted the female before she gave birth to the rare babies. And the versatile super-mom had previously had babies the "old-fashioned way" by mating with a male well before her two asexual reproduction experiences.

Booth doubts that the rare births were caused by environmental changes. He notes that while environmental stresses have been associated with asexual reproduction in some fish and other animals, no changes occurred in the mother boa's environment or routine.

It's possible that this one snake is some sort of genetic freak of nature, but Booth says that asexual reproduction in snakes could be more common than people think.

"Reproducing both ways could be an evolutionary 'get-out-of-jail-free card' for snakes," Booth says. "If suitable males are absent, why waste those expensive eggs when you have the potential to put out some half-clones of yourself? Then, when a suitable mate is available, revert back to sexual reproduction."

A reptile keeper and snake breeder, Booth now owns one of the young females from the study. When the all-female snake babies reach sexual maturity in a few years, Booth will be interested to see if they mate with a male, produce babies without a mate, or -- like their mother -- do both. In any case, these WW-chromosomed females will continue their version of "girl power," as any baby they produce will also be female.

Drs. Coby Schal and Ed Vargo co-authored the paper. Co-author Sharon Moore raised the snakes in the study. Co-author and veterinarian Daniel Johnson provided surgical sex testing on the snakes. NC State's Department of Entomology is part of the university's College of Agriculture and Life Sciences.

http://www.sciencedaily.com/releases/2010/11/101103111210.htm