Owing to the great diversity of life on our planet, scientists are still discovering new species to study and describe. It’s the ultimate achievement for a scientist, and many spend their careers seeking out new species in the most remote locations of the world. What’s even more exciting however, is when a scientist stumbles upon an unknown species that’s right under their nose. This was the case when a group of researchers discovered a species of lizard unknown to science-- on the menus of Vietnamese restaurants.
The newfound lizard, Leiolepis ngovantrii, is also of special interest because it is an all-female species that reproduces via cloning. Single-gender lizards are not totally uncommon, about one percent are thought to be able to reproduce via parthenogenesis, or spontaneous ovulation and production of offspring with the exact same genetic makeup.
The lizard was discovered by a father-son herpetologist team who were clued into the lizard’s cloning ability when they noticed that the members of the species all looked remarkably alike. They recognized the lizard as belonging to the Leiolepis genus, in which males and females have distinct morphological differences. Wherever the lizards were being sold, there were no males to be found.
The team suspects that the species is a hybrid from maternal and paternal lines of two related lizard species, a phenomenon that sometimes occurs in transition zones between two habitats. Genetic testing of mitochondrial DNA has allowed the team to identify the maternal species, but since this type of DNA is only passed down through females, the paternal species is still a mystery.
Although the species seems to be fairly common in this area, scientists say that single-gendered hybrid species are at a higher risk of extinction because they can’t produce much genetic diversity from generation to generation, which keeps a species viable and healthy in the long term. Genetic variation can only arise by random mutations, which have the same chance of being detrimental as beneficial. Others counter this by arguing the case for mules: hybrids, because their individual cells are more diverse than nonhybrids, can be tougher and more adaptable. Hybrids, like mules, can be really robust, and in some cases have preferable traits, although they are sterile. So in this case, the lizard is like a mule that can clone itself.
-Jane de Verges
Group A
It is so weird to me that a lizard can be asexual. It is crazy that a mutation for the females to produce asexually arouse at all. If a male were around would females switch to sexual reproduction? Would they even be able to switch reproductive methods? The diversity among live on Earth is truly incredible and never ceases to amaze me.
ReplyDeletePosted by: Sara Weaver
It’s funny but sadly ironic that this kind of asexual species can be considered at risk of extinction due to its lower genetic diversity, yet it’s being served as a popular dish. Although maybe this is helping promote its asexual lifestyle. Since it has to endure being hunted by humans, this would help it survive by not needing to find another individual of the opposite sex. I wonder if they eat the maternal species too?
ReplyDeletePosted by Daniel Solomon
This animal is amazing and another example of asexual reproduction in animals that could be taught in class. I was wondering what the status of these species are and whether or not considered endangered. When populations are in low numbers, genetic drift can occur. Where these animals in low numbers that may have resulted in this shift? Maybe the reason for just discovering these species now is because they have been rare for sometime?
ReplyDelete-Himanshu
Update:
ReplyDeleteI did a little more reading about parthenogenesis. In 2006, a female komodo dragon in a zoo produced a clutch of eggs via asexual reproduction. This was one of the first known cases of parthenogenesis in such a large lizard. This type of reproduction is very rarely seen in such complex animals, having been documented in just 0.1 percent of vertebrates, including sharks, turkeys, pythons, and some fish. It does not occur in naturally in any mammal species (that we know of), but scientists have successfully induced asexual reproduction in mice and rabbits, and interestingly enough, in 2007 a South Korean scientist successfully used this process to produce human embryos!
Because mammals use a XY chromosome system, all cloned offspring would be female. But reptiles use a ZW chromosome system, and have been known to produce viable male and female offspring via parthenogenesis. Scientists believe that because komodo dragons are native to the islands of Indonesia, females that get swept away to new islands would use parthenogenesis to start a new colony, then mate with her male offspring to create a sexually reproducing population again.
-Jane de Verges
All of that information is really interesting. And as always everyone wants to use that to drive them to solve human cloning. I think its a bad idea, we haven't evolved yet to clone, so lets not force things that aren't suppose to happen.
ReplyDeleteThe interesting thing is the exact same thing happens in Jurassic Park. It'd be interesting to some how find out if dinosaurs used the same methods as well.
-Peter Lucas
Imagine the disadvantages that comes with a cloning species, they must be quite likely to be victims of a bottlenecking event with similar DNA. has a case of a new species being discovered and then found to have become extinct ever been seen in the past?
ReplyDelete