Discussion of Malayan Pangolin 3 | Can’t Malayan Pangolins be released for ecological niche competition and species invasion?
2019/6/21 16:52:00 本站

Opinion 3: Malayan pangolin cannot be released because it occupies an ecological niche and is possible to result in exotic species invasion.


Biodiversity conservation has three levels: genetic diversity, species diversity, and ecosystem diversity.


When we talk about whether a great number of confiscated living pangolins could be released each year, a lot of experts have a common concern: these pangolins may cause a threat to indigenous species, leading to exotic species invasion.


 If we can determine that Malayan pangolin is not originated from China, then there are two possible consequences. The first one is that Malay pangolin grabs the ecological niche of Chinese pangolin. The second one is the potential hybrid of Malay and Chinese pangolins, which may disrupt the genetic purity of local species and cause indigenous species loss. This is irreversible." More than one specialist in the field of systematic zoology has expressed similar concerns.


According to current information, Chinese pangolins (Manis pentadactyla), native to China, mainly distribute in foothills and flatlands of Fujian, Guangdong, Guangxi, Yunnan, Guizhou, Hunan, Hainan, Taiwan, etc., with three subspecies being found in China. Malayan pangolins (Manis javanica) mainly range in Brunei, Cambodia, Indonesia, Laos, Malaysia, Myanmar, Singapore, Thailand, Vietnam, etc. In conclusion, Chinese and Malay pangolins have different distribution ranges: Chinese pangolin is in subtropical areas, Malay pangolin tropical areas.


In view of animal migration and the incomplete investigation into wild terrestrial vertebrates over the past years, Malay pangolin and Chinese pangolin share intersection, particularly in Yunnan, Guangxi, and other southern provinces. But does that mean Malay pangolin will trigger ecological niche competition? According to the current situation, the author doesn't have such a concern. Since the mid-90s, the number of Chinese pangolins has been slumped in southern provinces, and the declining wild population reflects that Chinese pangolins have been functionally extinct in mainland China. In other words, it is rare to see them in forests of southern China where is suitable for their survival. And it's difficult to increase its population in the wild.


From December 2000 to March 2001, Professor Wu Shibao, the expert on pangolins of South China Normal University, investigated the population density and quantity of Chinese pangolin subspecies in Dawuling nature reserve. According to his findings, there were 10 to 20 thousand Chinese pangolins in Guangdong province, but the population density and quantity are scarce when measured in the level of each suitable habitat averagely.


CBCGDF's recent rescue and training experience of pangolins in Guangdong shows that Malay pangolin begins to eat local ants, which proves that it can change its eating and living habits in a different environment. Malay pangolin will not cause ecological niche competition or change the population structure of local species in a short period due to its limited population.


Then what is the biggest risk after releasing Malay pangolin into the wild? A wildlife expert says, "the biggest challenge is genetic diversity loss." In consideration of insufficient research into the genetic mixing of pangolin, the author here provides an example of exotic species invasion as a reference.


Tilapia is originated from East Africa and was introduced as a commercial fish into China since the late 1970s. As an omnivorous fish, tilapia has a strong ability to survive in the wild, which makes it a problematic invasive species.


 Tilapia is a typical invasive species because it triggers competition with epipelagic fishes as well as pelagic ones. Currently, it causes great influence on Pearl River", according to fish experts. However, people hold a positive attitude to this invasive species and regard it as a commercial fish. Over the years of development, the tilapia breeding industry has evolved into a major pillar.


The statistics show that tilapia has become the fourth largest freshwater cultured fish. It is reported that tilapia is widely bred in 26 provinces and cities, including Beijing, Tianjin, Liaoning, Shanxi, and Xinjiang, with annual gross production of 158,000 tons and economic value of nearly 2 billion yuan.


Similar exotic species include cray, potato, and so on. The difference between them and Malay pangolin is that they have been scientifically domesticated after invading into China. Therefore, it's reasonable to release confiscated Malay pangolin on the basis of a compact assessment of its health, suitable habitat, and other necessary backgrounds, which may eliminate the concern of genetic loss.


As of exotic species invasion the increasing interactions with species, including plants, terrestrial and aquatic animals, microorganism around the world cannot be neglected. According to the first report published by IPBES in May, the number of exotic species in 21 countries has increased by 70% since 1970.


The increasing interaction with territorial species and the biodiversity loss are simultaneous with human activities. But human intervention and control seem ineffective. It is estimated that in China the economic loss caused by over 500 invasive species accounts for 1.36% of GNP each year. However, few measures have been implemented in the field of aquatic ecology and terrestrial wild vertebrate except interventions of several regions.



(Photo credit: CBCGDF)

Original Chinese article:


By / Wang Yanqing