From platypus to person – the sequence of events
When 100 researchers around the world pooled their work to successfully trace more than 160 million years of genetic evolution in the platypus, Conjoint Associate Professor Russell Jones knew he had been part of a breakthrough with far-reaching repercussions for scientific research.
Jones participated in the study with colleagues Dr Brett Nixon, also from the University of Newcastle, and Dr Jean-Louis Dacheux from Institut National de la Recherche Agronomique, in Tours, France.
The small group investigated reproduction in the platypus as part of a four-year international study, with their work focusing on the evolutionary development of gametes and fertilisation.
Our most distant mammalian relative, the platypus is unique in that it combines the features of a mammal with those of a reptile. The females lactate, yet lay eggs; they have a coat of fur to adapt to aquatic conditions; and males are equipped with venom similar to that of reptiles. It is these distinctive characteristics that give the platypus genetic innovations the genome study was able to identify.
Jones said the entire sequencing of the platypus genome was critically important to understanding the evolution of mammals and humans.
"If you look back 160 million years, as we have done, you will find the last common link between humans and the platypus," he said.
"The platypus is the earliest known mammal still alive. The information we obtain from determining its genome may be very powerful for understanding the importance of certain genes in humans.
"Humans suffer a lot of conditions, such as Cystic Fibrosis which takes many forms, each of which are caused by one of more than 300 mutations of that gene.
"If you can trace that gene through evolution as far as possible, you can see which parts of it have been filtered and which have remained unchanged and are, therefore, the vital components.
"The platypus is like the Rosetta Stone for reading the human genome."
The collaboration was published in the world’s most prestigious scientific journal, Nature, in May. The research provides an important tool for comparisons between humans and the platypus because it points to the crossroads where we evolved one way and our web-footed ancestor the other.
The project began in 2004 and was led by the Washington University Sequencing Centre, with funding from the National Institute of Health in the United States and the Australian Research Council.
Jones said the study would enable him to answer more questions about human reproduction.
"I am particularly interested in learning more about how and why human sperm mature in the male ducts after they leave the testes and why they need to spend time in the female tract before they are capable of fertilising an ovum.
"Now we have established this tool for comparisons between humans and the platypus, we will be able to study our work on platypus reproduction and how it may apply to the human system."