ANIMAL EXTINCTION: THE PROBLEM, A VICTIM, THE SOLUTIONS On the 19th March 2018, Sudan, the last male Northern White Rhino died [1]. Sudan was 45 years old when he died, well past the ideal reproductive age for males. Sudan suffered from several age-related problems and a severe infection in his hind right leg. These complications lead to his team of vets ultimately deciding to put him down. His death brought the population of Northern White Rhino down to two individuals, both of which are female [2]. The species (Full trinomial name: Ceratotherium simum cottoni) was driven to extinction by the action of poachers seeking to sell their skins and horns. According to a statement made by the South African Minister of Environmental Affairs Edna Molewa, the number of poached rhino in 2017 was 1028 individuals. There has been a slight decline since its peak in 2014 where the number reached 1215 individuals, however these are still troubling numbers considering the fact that only two individuals remain.
Figure 1: Recorded number of Rhinos poached in South Africa. Source: Poaching Statistics - Save the Rhino. https://www.savetherhino.org/rhino_info/poaching_statistics
With an average of 1095 rhinos killed per year over the past 5 years, is there hope for the rhino as a whole, let alone the white rhino? Despite the fact that there are only two female individuals remaining some techniques may be put to use to bring the species back from the brink of extinction. However, an important distinction needs to be made between extinction due to natural selection and extinction due to human impact. The common misconception is that extinction is a part of natural selection, in order for the gene pool to be improved, less efficient species need to be removed from it thus improving the gene pool as a whole. While this is true it was not the case of the white rhino. The species has a very keen sense of smell and acute hearing allowing effective communication and avoidance of predators. Furthermore, the subspecies size, strength, tough leathery hide and natural weaponry in the form of a keratinous horn makes it incredibly difficult to be killed by predators [4]. This species was in no way struggling to survive until their horns and skin became a desired product. It is very much in the interest of the governments of the world to preserve these species. Ecotourism is a blooming source of income for these countries with great biodiversity. By preserving this diversity, governments may ensure a steady income through such tourism schemes and also acknowledge it as another major pillar of its economy coming from the touristic sector. This is an added benefit to the continuous needed maintenance of any ecosystems which may be disrupted due to a species being driven to extinction amongst other activities, including the destruction of habitats through logging and other similar practices. Ecosystems may depend on what are known as keystone species, these species are the central link which binds all interactions in a habitat together. If these organisms are removed it will lead to ecosystem collapse, an event which is borderline irreparable. One such example would be the looming extinction of bees, which would lead to a complete reshaping of all insect pollinated plants in the biosphere. Many species are lead to the brink of extinction due to the demand for unique animal products such as ivory and skins, however, awareness is being raised and the populous is beginning to be educated regarding the importance of the conservation of species. Endlings such as Sudan are being used as symbols of the importance of conservation. By being the martyrs of their species, they can
hopefully incite a change in stance of the policy makers we rely on to make a meaningful change. They can set up conventions and treaties in relation to the conservation of biodiversity, an example of which is the International Convention on Biological Diversity established by the United Nations in 1993. This document presented a general consensus that biodiversity should be a major focus in global efforts. It ensured that the decline in biodiversity being observed will not be overlooked and how should be in the global interest to protect it, an endeavour which should keep not only our generation in mind, but the ones to come. This would be done by evaluating any potentially unsustainable practices and bringing them to an immediate halt [5]. Prevention is important in the conservation of species however dedicated scientists are still trying to find ways to retroactively bring species back from the brink of extinction. A meeting in Vienna in December of 2015, under the title “Conservation by Cellular Technologies� saw the proposal of several possibilities to save the species. Natural reproduction is now considered unfeasible since, over the years there have been many attempts to breed the rhino in captivity, very few of which resulted in viable offspring. Instead, in vitro fertilisation (IVF) is being considered. By fertilizing an oocyte obtained from one of the two remaining females left in captivity with sperm obtained from Sudan which is kept in cryostorage in Kenya a viable infant could potentially be produced. This method still needs more testing in other model species however if it is found to be successful it can be modified to bring other species back from the brink [6].
Figure 2: A flowchart of solutions put forward during the “Conservation by Cellular Technologies” meeting. Source: Saragusty, J., Diecke, S., Drukker, M., Durrant, B., Friedrich Ben-Nun, I., Galli, C., . . . Hildebrandt, T. B. (2016, May 3). Retrieved from https://www.ncbi.nlm.nih.gov/pubmed/27142508. Flow diagram detailing the various options discussed during the “Conservation by Cellular Technologies” meeting that took place in Vienna in December 2015. [Detailed are the resources and flow of the process using natural gametes (right side of the diagram) or constructed gametes (left side of the diagram), leading eventually, so we hope, to live birth of a northern white rhinoceros (NWR) and later on to a viable and self sustaining NWR population. SWR, southern white rhinoceros; KOGR, knockout gene replacement; PM, post mortem; IVF, in vitro fertilization; ICSI, intracytoplasmic sperm injection; iPSCs, induced pluripotent stem cells; PGCs, primordial germ cells; ICM, inner cell mass.].
The process of IVF is still regarded as taboo in come scientific communities, however in the interest of preservation of species all options need to be considered. Some in vivo
procedures are being performed, such as in the case of the San Diego Zoo who have successfully impregnated a female southern white rhino via artificial insemination [7]. It is important to note that the process of sperm extraction via electroejaculation and egg extraction via ovulation stimulation are both stressful on the specimen and require the use of anaesthetic, a procedure which is ideally avoided. As the saying goes, an ounce of prevention is worth a pound of cure, the ideal situation would be never needing to bring a species back from the brink of extinction in the first place. However, if the pregnancy in the San Diego Zoo produces a fruitful offspring a hybrid could possibly be produced between the Northern and Southern white rhino species and while it is not a perfect solution, it is still a solution. Many measures are being considered to prevent similar extinctions from happening. One such concept suggested in the meeting in Vienna was the concept of BioBanking, an idea originally proposed by Veprintsev and Rott in 1979. This concept suggested that the gametes of dwindling species could be preserved via cryostorage in the case of extinction. In order for this strategy to be feasible cryopreservation techniques need to be perfected to ensure that the gametes will still be viable and unaffected when removed from storage. Several ethical issues may arise through these solutions, the solutions need to cost effective, effectively raise public awareness and be a long-term solution which does not disrupt the original ecosystem. Several solutions have been proposed and via funding through government schemes they may be put into action, potentially restoring the species who were sent to the brink of extinction due to human action.
References [1]
(2018, March 20). After Last Male's Death, Is the Northern White Rhino Doomed? Retrieved May 21, 2018, from https://news.nationalgeographic.com/2018/03/northernwhite-rhino-male-sudan-death-extinction-spd/ [2]
(2018, March 20). Sudan, the Last Male Northern White Rhino, Is Dead - The Atlantic. Retrieved May 21, 2018, from
https://www.theatlantic.com/science/archive/2018/03/sudan-northern-white-rhinodeath/556058/ [3]
(n.d.). Poaching Statistics - Save the Rhino. Retrieved May 21, 2018, from https://www.savetherhino.org/rhino_info/poaching_statistics [4]
(n.d.). Species Description - Northern White Rhinoceros. Retrieved May 21, 2018, from https://rhinorhinorhino.weebly.com/species-description.html [5]
(2018, May 28) Convention on Biological Diversity - United Nations. Retrieved May 28, 2018 from https://www.cbd.int/doc/legal/cbd-en.pdf [6]
"Rewinding the process of mammalian extinction. https://www.ncbi.nlm.nih.gov/pubmed/27142508. Accessed 8 Jun. 2018. [7]
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"Zoo Pregnancy Raises Hopes of Preserving White Rhinos | The ...." 18 May. 2018, https://www.the-scientist.com/?articles.view/articleNo/54612/title/Zoo-Pregnancy-RaisesHopes-of-Preserving-White-Rhinos/. Accessed 29 May. 2018.