Among animals, mammals account for more than 15,000 species of vertebrate animals that have the ability to self-regulate their body temperature, have hair, and, in the females, produce milk. In the study of mammalogy, the branch of science that deals with mammals, there has been a growing concern at the rate of mammalian species nearing extinction. Thus, the Endangered Species Act of 1973 was put forth to protect animals and plants on the verge of extinction. It also provides policy to the Fish and Wildlife Service to determine a listing of endangered animals and to develop associated recovery programs. The Fish and Wildlife Service subsequently has registered a policy for controlled propagation of species listed under the Endangered Species Act for a restricted administration of conservation and recovery practices where the purpose is to oversee the "production of individuals, generally within a managed environment, for the purpose of supplementing or augmenting a wild population, or reintroduction to the wild to establish new populations." A sub-focus of this policy is concerned with activities involving genetic development of offspring in a laboratory or other controlled environment where the policy requests that propagation programs have a minimal adverse affect on existing wild populations of endangered animals. Given the concerns over the ever-expanding list of endangered species, as well as considering the substantial scientific developments in genetics, would it be prudent and ethical to direct recovery efforts at genetically cloning endangered species, or even extinct species with recoverable DNA, in order to repopulate these animals for modern day species diversity?
Cloning endangered species offers a solution to preserving and propagating those animals that have poor reproduction rates in captive environments until which time that their habitats can be restored and they can be successfully reintroduced to the wild. One of the greatest advantages to genetic cloning is that it expands the genetic diversity within a gene pool, which is otherwise limited when only a few animals within the species remain. Genetic diversity is the key to endangered species conservation, but consequences relating to the methods to arrive at this point may be incurred.
The controlled propagation policy raises concerns over the use of technology other than the breeding of parental stock to reproduce and preserve a species. While genetic diversity could be maintained through cloning, there may pose the possibility of some adverse genetic effects if only a portion of the gene pool is enhanced. Also of concern as addressed by the policy is that problems may be presented if the controlled production of a species (i.e. through cloning) decreases the animal's natural capacity to survive, reproduce, and adapt in the wild.
The Act does not outwardly address the ethical issues to genetic cloning or other manufactured means of propagating an animal for endangered species conservation, but the frequency of loss of surrogates, embryos, and newborns is considered under the idea that "risk" should be minimized. The controlled propagation policy of the Endangered Species Act is very careful over allowing potential harm to come to an animal protected under the Act, stating that recovery efforts must "minimize risks to existing wild populations." The degree of minimal risk described by the Act is subjective and has been recognized as being "insufficient" in its detail by the Fish and Wildlife Service, but an outlined list of risk examples is provided in the policy, one concerned with the removal of, or risk to, parental stock that could lead to an increased possibility of extinction or decreased genetic variability within naturally occurring numbers in a species.
Cloning technology requires a mother to act as a surrogate. While conservation biologists may be in support of, or on the fence about, cloning as a method of endangered-species conservation, the concept of using either a wild or captive endangered female of the same species to assist in reproduction or act as a surrogate mother is unfavorable as the risks may prove too great. To circumvent the risk of adversely affecting the present-day numbers of a species by using a surrogate of that species, or even to reintroduce a species that has been identified as being extinct, scientists have delved into utilizing methods of interspecies cloning to reproduce an animal using a surrogate mother of another, less endangered animal.
Interspecies cloning is a two-fold process whereby the cells of a surrogate species are combined with the endangered or extinct species to produce an embryo of the desired species, then the designed embryo is implanted into the surrogate mother. It is thus necessary that the reproduction biology of the endangered species considered be well studied to maximum the effectiveness of cloning success. In January 2001, a milk cow gave birth to an endangered relative known as a gaur. Unfortunately, two days later the ox-like calf died of an uncommon disease called scours, which some biologists believe may have been induced by the genetic cloning process (it is estimated that baby clones are three times more likely to die than natural young due to increased risk of infection, underdevelopment, and abnormal growth development). While the death may be considered a negative hit to cloning, it did prove that interspecies transplant can be induced and the birth of an endangered animal can occur. Shortly after, a house cat was reported to have given birth to the endangered African wildcat, another cat yielded an Indian desert cat, a common eland gave birth to a bongo antelope, a domestic sheep produced a mouflon sheep, and a white-tailed deer generated a rare red deer. All of these interspecies embryo transfers yielded live births. The success of these clonings gives hope to preserving other endangered species as well.
One of the most endangered species, the giant panda, Ailuropoda melanoleuca, was protected by the Act in 1984. While conservation efforts and land preservation have been provided for this icon of the World Wildlife Fund, illegal poaching, continued encroachment on their environmental lands, and difficulty with captive breeding programs have made it difficult to even maintain the scarce population of fewer than 1,000 of these gentle animals. About ten percent of the panda population is held in zoo facilities where their captive reproduction problems have been thoroughly studied. It has been concluded that grouping successful mating pairs together is too difficult to be a viable means of facilitating their recovery, but the giant panda has benefited from assisted reproduction through artificial insemination. It is unfortunate that their limited distribution in the wild makes it difficult to productively reintroduce them, which further compounds the problem of repopulating their species. One possible solution does exist; they are the subject of interspecies transfer experiments in cloning.
The biotechnology company Advanced Cell Technologies (ACT) of Boston, Massachusetts, has considered the panda to be one of the best candidates for endangered-species cloning, and has discussed cloning plans with the government of China, the single native home of the panda. Chinese scientist Dayuan Chen published a paper in the journal Science in China in 1999, describing how his team fused the skeletal muscle, uterus, and mammary gland cells of a panda with the eggs of a rabbit and then developed the cloned cells into blastocysts within the laboratory. Working with the Chinese, ACT has plans to further this development by using eggs from female American black bears and combining them with cells obtained from the late pandas Hsing-Hsing and Ling-Ling of the San Diego Zoo, to produce cloned giant panda embryos that can be implanted in a surrogate female black bear. They are hopeful that this interspecies transfer will occur since the black bear does have a history of a successful birth of a transplanted embryo of another black bear.
If successful genetic cloning through interspecies transfer could save the giant panda from extinction, the Endangered Species Act will…