183 Scholarship Question: Return of the Dodo

Could species become de-extinct?

Extinction is part of the evolution of life. The loss of an organism leaves a vacant niche and provides the opportunity for another organism to evolve into that ecological space. The rate of natural (or background) extinction is about 0.1 species per million years. The extinction rate over the last 400 years is estimated to be around 1000 times greater than this. This is because human activity since 1600 AD has directly or indirectly caused the extinction of over 400 known species. These include the dodo, the moa, the Tasmanian tiger, and more.

Technology has now developed to the point that DNA can be extracted from the 30,000 year old bones of Neanderthals. Technology also now enables animals to be routinely cloned.

Many organisms on the brink of extinction are now having DNA, sperm, and egg samples cryogenically frozen to preserve them in the event of their extinction in the near future. The hope is that technology will enable the organism to be cloned and so return to the world in the future.

Many argue that now, with the ability to extract DNA from fossils and to clone animals, some of the animals that were exterminated by humanity should be returned to the world (de-extinction). There has been only one case of de-extinction. The Pyrenean ibex was a subspecies of Spanish ibex. It became extinct in 2000. Scientists used DNA from the last female to create 285 cloned embryos that were implanted into Spanish ibex. In July 2003, one clone survived to birth, but died after only a few minutes due to lung defects.

The dodo (Raphus cucullatus) is a possible candidate for de-extinction. Endemic to the island of Mauritius, the dodo was first recorded in 1598 and was exterminated by 1662 so completely that only one complete skeleton exists and no complete specimen is known. Scientists are not even sure what the dodo looked like because of the variation in sketches by 17th century artists. However enough DNA has been extracted from bone that the genetic relationship of the dodo to other birds has been identified.

Phylogeny of the dodo

Victoria crowned pigeon

Nicobar pigeon

Rodrigues solitaire (extinct)

3D Dodo (extinct)

Tooth-billed pigeon

The flightless dodo stood about 1 metre tall and weighed between 10 and 20 kilograms. Only one egg exists and its authenticity is in dispute. The dodo egg, apparently, is larger than an ostrich egg. The Nicobar pigeon measures about 40 cm long and weighs about 500 grams. It lives in coastal regions of Andaman and Nicobar Islands, India. Its egg is about the size of a chicken's egg.

J. Patrick Fischer CC 4.0

1. Analyse the information provided and integrate it with your biological knowledge to discuss:

• The evolutionary and ecological factors that contribute to declining populations and increasing rates of extinction.

Use examples to support your discussion. • How humans could manipulate the transfer of dodo DNA to restore a population of dodos to Mauritius and the possible biological implications of doing this. • Justify your opinion on whether restoring extinct organisms is a possibility.

You may use extra paper if needed.