Research and Evaluation of Reproductive Cloning of Sumatran Tigers

Reproductive cloning of Sumatran tigers is carried out using a technique called somatic cell nuclear transfer (SCNT). First in the process of SCNT, a somatic (body) cell to clone is obtained. A somatic cell from a Sumatran tiger is used to make a genetically identical tiger. To do this, somatic cells are taken from the tissue of the Sumatran tiger to be cloned and are maintained in the lab in a state which stops the cells from dividing. The next step in the SCNT process is to remove the nucleus from an unfertilised egg cell. An egg cell is removed form a female of the Sumatran tiger species. The nucleus is removed from the egg cell (enucleated). This is done so that only the genome of the Sumatran tiger to be cloned will be in the egg cell. The clone will not have the genome of the Sumatran tiger from which the egg was taken. The next step is to fuse the cells. The enucleated egg is fused with the nucleus from one of the somatic cells from the lab, which has been taken from the Sumatran tiger to be cloned. These two cells are fused using an electric shock. The egg cell now contains the genome of the Sumatran tiger to be cloned, as the genome came from the somatic cell. The egg cell is then electrically stimulated to start dividing until an early embryonic stage is reached. The last step in the SCNT process is embryo implantation. The embryo is implanted into the uterus of a surrogate mother Sumatran tiger, where it grows for the normal gestation period. After this time, the baby is born and the result is a baby Sumatran tiger which is a clone of the Sumatran tiger from which the somatic cell was taken.

There are biological implications which can occur as a result of cloning Sumatran tiger species. Advantages of cloning the Sumatran tiger species is that the cloned tigers can be used to increase the number of endangered Sumatran tigers. The Sumatran tiger is an endangered species and there are estimated to be only between 400-600 Sumatran tigers remaining in the wild today. By cloning the Sumatran tiger, numbers of Sumatran tigers can be increased, reducing the species risk of extinction. Another advantage of cloning the Sumatran tiger species is that individuals can be selected to be cloned. Tigers which are more disease-resistant can be cloned so that the Sumatran tiger population builds and increases with disease-resistant Sumatran tigers. Thus, if a disease strikes the population, the effects would not be as crippling. Once the numbers of Sumatran tiger have been increased by cloning, they could be bred normally to further increase numbers. Saving a species from extinction maintains the diversity of the world's tiger population for the future. Once the Sumatran tiger numbers have increased and the tigers are allowed to interbreed normally, this will increase their genetic diversity compared to cloning alone, which reduces genetic diversity. This increased genetic diversity would increase the Sumatran tiger's chances of surviving in the wild in future. Once tiger numbers have increased sufficiently, the tigers could be re-introduced into the wild to repopulate their natural habitats. There would be increased opportunity for both local and overseas visitors to see the unique tigers in their natural habitats.

Disadvantages of cloning the Sumatran tiger are that the success rate is very low. Usually less than 5% of the somatic cells used for cloning develop into live foetuses. Of these, few survive through to being born. Those that do survive often have many physiological defects such as cardiovascular defects, impaired immune systems and early onset arthritis which results in their early death. The techniques used for cloning are complex and expensive compared to selective breeding, which may limit the numbers of Sumatran tiger that can be cloned economically. There are ethical concerns about the treatment of cloned animals and whether the ends justify the means in terms of animal suffering and benefits for humans. This is due to the low success rate of Sumatran tiger cloning and the health issues surrounding cloning. Also, as the Sumatran tiger clones are genetically identical, there is a loss of genetic variation compare to other animals which reproduce normally. If the cloned Sumatran tigers have a genetic defect, they will all have the same defect as they do not have the genetic variation of naturally occurring species.

Genetic variation allows animals to adapt to a changing environment and environmental conditions and to resist disease through naturally occurring genetic mutations and characteristics. Because of this, all the cloned Sumatran tigers will be susceptible to the same disease. The lack of genetic diversity is a disadvantage especially when the numbers of tigers are very small. Due to their vulnerability to disease, all the tigers could be affected and there could be a great decrease in numbers surviving because they would lack the diversity that would enable them to survive. The population could become inbred due to the lack of genetic diversity and there may not be enough Sumatran tigers in a wild population for them to breed with, to increase their genetic diversity. This means the cloned Sumatran tigers would always be susceptible and vulnerable.