Pangolins are unique as they are the only mammal to be covered in scales. Even though they are scaly, photos of them are typically met with "awwws" from the viewers who find them adorable. Importantly, though, pangolins play an essential role in maintaining their ecosystem. Their other "unique trait" is that they are the most trafficked wild animal in the world, with more than 900,000 poached in the past two decades. Much of this is due to their high value for use in traditional medicine that requires the use of pangolin meat and scales. This has pushed many pangolin species to the brink of extinction. In particular, two pangolin species, the Malayan pangolin (Manis javanica) and the Chinese pangolin (Manis pentadactyla), are under acute survival pressure. These species have been listed as critically endangered on the Red List of the International Union for Conservation of Nature (IUCN) since 2014.
With World Pangolin Day being celebrated on February 15, it is befitting that new research presenting high quality genomic data for these Pangolin species puts a spotlight on the genetic vulnerabilities and extinction risks for Malayan and Chinese pangolin species. This work is a collaborative effort of Chinese scientists involving Yan Hua's team from the Pangolin Conservation Research Center of the National Forestry and Grassland Administration, Tianming Lan's team from Northeast Forestry University, and Qiye Li at BGI-Shenzhen. The study has been published in the Open Science journal GigaScience.
The starting point for their analyses was generating genome sequences of the Chinese and Malayan pangolin species at a significantly higher resolution than what is currently available. Having such high quality data in the form of a nearly gapless chromosome-scale sequence is invaluable for obtaining essential information that are important indicators of genetic health and risk of extinction for any population. For this, the analyses carried out included genetic diversity estimates, which indicates how much genetic variation there is between individuals in a population. The greater the variation, the more genetically healthy future generations can be. Similarly, other parameters, such as the level of inbreeding within a population can be assessed and indicate the likelihood of there being major health issues inherited over time. These analyses can aid in focusing on the best ways to carry out rescue operations, such as whether selective breeding is essential.
The Chinese scientists used their high quality data as a reference point, along with previously released genomic data from 37 Chinese pangolin and 72 Malayan pangolin individuals, to re-evaluate the conservation genetic status of five pangolin populations. They found that the overall genetic diversity was surprisingly high— which is a positive sign for the genetic health of a population; but, their fine-grained analysis showed that some of these populations are at higher risk of extinction than the others.
Specifically, based on the genetic data for one Pangolin population, the scientists ascertained that this population had suffered a much faster and sharper population decline within the past 10,000 years compared with the other populations in their study. Additionally, other genetic parameters in their study indicated this population in particular was at a very high risk extinction. Adding to this, their analysis of a pangolin specimen from Taiwan revealed similarly distressing data. Future work is required to solidify the extent to which specific pangolin populations are at extinction risk due to serious survival pressures. The research data also indicate that further studies on the differences between the localities of these populations should receive more attention as they have the ability to aid in guiding the genetic rescue efforts that are already underway.
Professor Tianming Lan says: "In addition to aiding the management of illegal poaching and trafficking, the Chinese government has built a breeding center for the conservation of both Chinese and Malayan pangolins and has developed an artificial breeding and reproduction program. With the assistance of this data, we can better evaluate the genetic rescue strategies for wild populations by rewilding and releasing these captive individuals in the future."
