Lizard lunch
The story
The award for ‘most observant scientist during his lunch break’ this week must go to Ngo Van Tri of the Vietnam Academy of Science and Technology who noticed something odd about the tank of lizards at his local restaurant.
The reptile scientist noticed that the lizards were all female and of an identical size (and all heading for the deep fat fryer before he told the restaurant owner to hold on to them for a while). He contacted a US specialist, Dr Lee Grisner, who flew out to see this for himself.
Dr Grisner arrived at the restaurant after a gruelling journey only to find that the chef had cooked all of the lizards after getting drunk and so had to persuade locals to go out and catch some more. Luckily this lizard is common in the area and he managed to collect over 60 lizards which he noticed were all female.
After studying the appearance and carrying out DNA profiling he concluded that not only was this a new species, Leiolepis ngovantrii, but they were all genetically identical – this lizard reproduced by cloning.
In the world of vertebrates asexual reproduction is very rare but a number of species of reptile and fish do resort to parthenogenesis, or self-fertilization, especially when faced with adverse environments, pollution or over-hunting (or being held captive in Jurassic Park as the dinosaurs in the film of the same name). The eggs of the Leiolepis ngovantrii have a full complement of chromosomes already and so there is no need for fertilisation.
It is thought that the lizard arose from a hybridisation of two similar species. This normally results in sterile offspring, such as the mule, but in this case it produced offspring that could reproduce, just not in the usual way.
Teaching idea
This story could be used as an interesting was of engaging the class when talking about reproduction.
Textbooks usually give plants and bacteria as examples of living things that reproduce asexually but looking at a vertebrate that can clone itself it gives this topic an interesting spin.
You could also use the fact that this lizard is a new species that came about from the hybridisation of two others to talk about what we mean by a species and take a look at other animal hybrids (see weblink below)
Teaching resource
I have created a lizard lunch PowerPoint which can be shown to KS4 biology classes.
The slides discuss the story and ask questions about the lizards and how they reproduce. The final question ‘Do you think it is an advantage or a disadvantage for the lizards to be able to reproduce like this?’ could be used to discuss the benefits and drawbacks of asexual reproduction. This species is healthy in the short term because it has the genes of a successful mother but is at danger of extinction because of its inability to adapt to a change in its environment.
Weblinks
Website that contains images and information about some more hybrid animals
News story from CNN
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