Endemic species are those that live in limited, unique areas to which they are used to. In these terms, some endemic animals are a characteristic of their land. They are fascinating and amazing to us humans. Therefore, many of the endemic species become aims for all-encompassing exploitation. Unfortunately, a lot of them are already extinct, and now we can only read outdated information about them and look at inaccurate pictures or photos.
There are many factors for animal extinction, both anthropogenic and natural. Now we will look at some extinct species, where did they lived and why did they extinct.
Extincted Endemics: Examples
Mauritius island, near to Madagascar, was a homeland for this famous bird. This small and distant island was first discovered only in the 13th century by Arabs. Later, in the beginning of the 16th century, the island was visited by the Portuguese. Yet, the real disaster for dodo was initiated by the Dutch, with whom thestory of a human invasion to the island started [1,2].
Figure 1. Mauritius Island – land of the dodos (1).
Many ships had been stopping on the island during the 17thcentury to refresh supplies. It was a whole new land, therefore people wanted to use it entirely by planting crops and releasing animals who were alien to the ecosystem [1]. These factorsbecame the main reasons for the dodo extinction. That is, pigs, were especially dangerous for birds’ eggs; cattle and rats, were feeding on local plants and crops; cats predating on birds’ chicks – all founded a large competition for food and survival for thelocal dodo, which were not ready for it. Also, people needed more land for other activities which led to Mauritius’s deforestation, making the dodo and other endemics go deep into the forest [1,2].
Figure 2. Dodo bird. One of versions of its appearance (2).
Such sudden changes were unbearable for the dodo, so its population started decreasing in the same century. The year 1681 is the last approved time when the dodo was mentioned insailors’ documents [1,2].
These zebra-like herbivores, quaggas, were the endemics of South Africa [3,4,5]. They were somehow similar genetically to plain zebras. However, they had their own personal haplotypes, which meant their divergence from a main group occurred more than 100,000 years ago [3].
Figure 3. South Africa. Big, but limited territory of quaggas in the past(3).
The first description of the quagga was published in 1785 along with its first given name. Its modern name, however, was offered much later. There had been a lot of discussions about it and the names of other zebra species due to preceding confusion on this question. [4].
Figure 4. The extincted quagga. Approximate colourful appearance(4).
The quaggas mostly were suffering from permanent hunting. Their skin was valued as high-quality, thus leading to the deliberate killing of animals. Besides, farming was wide-spreadin South Africa at that time, which made quaggas leave their lands, leaving pastures and water areas behind. Additionally, some commentaries contained information about shooting quaggas as a part of sport activity [4,5].
Finally, their number decreased dramatically due to thesereasons. Considering experts’ opinions, the quaggas extincted in the 1870s. The last known individual died in 1883 in the Amsterdam Zoo [4].
Once Tasmanian tigers, or thylacines, who were marsupial carnivores, had been living in Australia. However, due to sea level increase at the end of the ice age, small population of them on today’s Tasmania was divided from others on the mainland of Australia [6,7,8]. The Thylacines of Australia went extincted long ago, which is explained also by introducing the dingo dogs[6].
Figure 5. Australia and Tasmania (below) (5).
The Tasmanian tiger was discovered in the 1800s by Europeans who were exploring the island [3]. Later, in the 19th and the 20thcenturies the thylacines became a scapegoat for sheep demise on the island. As a result, government, with the intention to solve this problem, decided to reward each person for killing the Tasmanian tigers [6,7,8]. According to sources, the last thylacine was killed in the wild in 1930, and the last of them died in a Tasmanian zoo in 1936 [6,7,8]. The Tasmanian tiger was formally claimed as extinct only in 1986 [8].
Figure 6. Tasmanian tiger (thylacine). Black-and-white photo from zoo (6).
At first glance, the thylacines became extinct because of intentional elimination, concurrently trapping for trade and zoos, and obvious exploitation of the island [8]. No doubt that humanshad an influence on their extinction; however, the thylacines had already had one problem that preceded their rapid decrease long before humans arrived.
The Tasmania island isolation, mentioned above, led to a limitation of genetic diversity among the thylacines. Some research of the mitochondrial DNA of chosen thylacine samples showed a very high similarity level between them, calculated as 99% and above [6]. Such low genetic diversity describes not only a small range of population, but also a lack of new genes which could become factors of evolution or, for example, increase resistance to diseases.
Concluding Remarks
As we can see, human activity has an enormous effect on thesurvival and extinction of many species, especially those that are endemic. Such animals are vulnerable as they are used to live in one stable ecosystem without any disturbance from outside. Most of them would likely have low genetic diversity because of long isolation and short-ranged population which results in the inability of the species to resist and survive after significant changes in their life. Consequently, when people introduce new species to the endemic ones and change untouched nature for themselves only, they upset the balance, thus disturbing the well-being of the local animals. People’s careless chasing after their own goals builds a foundation for severe consequences for the endemics and other species.
Thanks to the extinction agenda and, sadly, to already extincted animals, people know about this problem. In order not to tell the next generations about such animals only by the photos and the documents, humanity should care more to save the ecosystems for the sake of endangered species now.
REFERENCES
FIGURES
https://doi.org/10.1038/443138a
https://cdn.britannica.com/97/195697-050-69602782/Tasmania-Australia.jpg
https://media.australian.museum/media/dd/images/Some_image.width-1200.2777446.jpg
Supervisor: Emine ARSLAN
