Snake study makes cover of Nature
Image courtesy of Nature |
The paper is based on research partly conducted at the University of South Australia’s City East histopathology laboratories by an international team of scientists from the Netherlands, the USA, Israel and Australia.
The study – which made the cover of the July 31 issue of the influential scientific journal – challenges previously-accepted notions of how fanged snakes evolved and helps explain the spectacular diversity of snakes seen today.
Many snakes use syringe-like fangs to inject venom into their prey. Sometimes these are located at the front of the jaw — as in cobras and vipers — and sometimes at the back, as in grass snakes. Whether each group shares the same evolutionary origin has been a controversial topic for biologists.
The researchers (led by Freek Vonk of Leiden University) looked at fang development in 96 snake embryos covering eight species to get a better idea of where the venomous teeth originate.
Surprisingly, they found that both front and rear fangs arise from the back of the upper jaw, but the front fangs migrate forwards during embryo development. On the other hand, the rear fangs form a specialized zone in the tooth-forming layer that stays put.
The findings suggest that the back region of the tooth-forming layer in the snake jaw became uncoupled from the rest of the teeth during evolution, enabling the back teeth to evolve independently with the venom gland. This could explain the massive expansion of advanced snakes that occurred during the Cenozoic era, resulting in the wide variety of snake species we see today.
Associate Professor Tony Woods, of the Venoms Research Group at UniSA’s School of Pharmacy and Medical Sciences, says it is most extensive study of its kind ever to be undertaken.
“Gathering the range of snakes required was a major undertaking, and UniSA played a significant role in providing the animals – with the help of adjunct research associate Peter Mirtschin – as well as devoting laboratory space and facilities to enable the samples of the animals to be collected and processed.”
Woods says further work on the association with venom gland development is in progress.