Chief Science Correspondent
Animal cloning has been common practice since 2003, when the sheep “Dolly” was conceived using
However, recent studies suggest that the technology to clone animals on a massive scale may be available
sooner than previously thought.
The Brasilia Zoological Garden recently began to discuss using cloning to restore the
populations of endangered species. Now, the movement towards this procedure known as “de-extinction,” has spread to include a wide variety of organisms that have either become extinct or remain critically at risk.
Last year, a biologist at the University of McMaster announced that the scientific community was on the verge of sequencing the wooly mammoth genome, a mass of information that could make revival of the species possible.
previously in development on animals in South Africa, Iberia and Ethiopian among others,
according to Spiegel Online.
In fact, in a 2000 study published in the journal Cloning, a group of neurologists and animal scientists
demonstrated a successful usage of this method to restore the Indian bison population.
However, it is important to note that while cloning may seem promising, it may be dangerous. While
this technology meets the short-term goals by creating new individuals, it is important to note that
the projects will not solve the long-term problems of habitat destruction that these species are
Additionally, introducing individuals into the wild may affect the ecosystem in unintended ways.
Calgary Zoo Centre for Conservation biologist Axel Moehrenschlager said extinct species may by
particularly dangerous because their ecological roles are difficult to predict.
“What if we bring back something that is actually an excellent vector for diseases, for example, that
could affect livestock or other species or ourselves?” Moehrenschlager said. “These are looming
Transplanting these individuals into their native environment or non-native environments might
appear to save the species’ fates by temporarily restoring the ecosystem and replenishing the
However, it is important that the long-term issues of deforestation, pollution and general habitat
fragmentation continue to be considered. Without proper regulation, these habitats will deteriorate
further, and the replenished populations will not be able to persist. In fact, until greater action is
taken, the fragmented habitats will actually be unable to support the new individuals.
Furthermore, the clones would not add genetic diversity to the existing populations, and may limit
the diversity of revived species. If the new populations are too small, they will be susceptible to
inbreeding. This is known as the bottleneck effect. If the team restores an extinct or endangered
population with a small number of individuals, future generations will be prone to a higher incidence
of harmful genetic mutations that could affect their health. The problem with clones is that they are
exact copies of another individual; therefore, introducing a clone into a population will increase,
rather than prevent, the effect of inbreeding.
Based on this information, I constructed a model to examine the potential effects of cloning endangered species in the Brazil project.
The project has targeted eight different species, which have been declining in Brazil in recent years.
The species are the jaguar (Brazil population size 5,000, male-female ratio 58:42); the black lion
tamarin (1,000, 60:40); the maned wolf (20,000, 52:48); the bush dog (10,000; 42:58); the gray
brocket deer (1.4 million, 62:38); and the South American coati (80 million, 50:50).
The American bison and the collared anteater were both studied as well, but I had problems finding
data on their Brazilian populations. The American bison has no native populations in Brazil, and I
could not find information on the collared anteater. Therefore, both of these species were excluded
from my analysis.
Using these numbers, I was able to calculate effective population size (Ne). This value gives a better
idea of how these populations are thriving on an ecological scale. There are actually many ways to
calculate Ne, but I used sex ratios because it was required for my next calculation, which used a set
formula to show quickly the populations inbreed per generation.
By plugging in these numbers, I found that the populations tend to have very small increases in
inbreeding per generation. After 50 generations, the tamarin’s inbreeding increases by only 2
percent. Most other species were much lower, generally increasing less than 0.01 percent.
From here, I could look at how adding clones would add to those inbreeding rates. I decided to look
at what would happen if just enough individuals were added to the population so that the sex ratios
I created a model to show how the inbreeding would increase initially and per generation, by looking
at initial rates and sexual maturity ages. I found that inbreeding per generation actually happens
more slowly (15.79 percent) when clones are added, because the populations are physically larger.
However, the initial cost of adding clones does add a significant (50.06 percent) increase in
inbreeding even after 50 generations.
Additional factors to consider include the effects of population fragmentation, fertility, changing
population sizes, mating behavior, because some species actually have instincts to prevent
inbreeding, ideal population sizes band the current initial inbreeding rate right now (my model does
not currently reflect this factor).
However, these numbers are promising. In some cases it appears that clones can be added to increase Ne without drastically harming inbreeding values.
However, while cloning appears to serve as a potentially viable option for improving the ecosystem, and may be the only way to restore certain important, but extinct species, artificial inflation should obviously not replace efforts toward conservation and prevention of further damage.