Researchers at the Wildlife Institute of India, Dehradun, had for long been puzzled by the features of hog deer at the Keibul Lamjao National Park in Manipur. Though larger, with no speckling, and sporting a brighter ochre coat and bulkier antlers compared to the rest of their species India, they were assumed to be the western hog deer species. However, a genetic intervention has now revealed that the KLNP population of hog deer is the eastern hog deer species – earlier believed to be confined to Southeast Asia.
“The large bodies and antler size of the hog deer at KLNP always bewildered us but no one could explain the reason,” said Pradeep Kumar Gupta, a researcher at the Wildlife Institute of India, Dehradun. “It was only after we conducted a genetic sampling of the population that we realised that the KLNP hog deer population is the endangered sub-species of hog deer which, according to the International Union for Conservation of Nature Red List of Threatened Species list, is not found in India.”
The western hog deer (Axis porcinus porcinus) and the eastern hog deer (Axis porcinus annamiticus) are two sub-species of the hog deer. According to the Red List, the former is found across Pakistan along the Himalayan foothills and throughout Nepal, India and Myanmar, while the eastern hog deer’s habitat is in Thailand, the Indo-China, Laos, Cambodia and Vietnam, with its western limits in central Thailand.
Funded by the Ministry of Environment, Forest and Climate Change and published in the journal Scientific Reports, the study was conducted between 2010 and 2018. The researchers collected 77 hog deer samples from Dudhwa National Park (Uttar Pradesh), Jim Corbett National Park (Uttarakhand), Kaziranga National Park (Assam) and KLNP. Samples, comprising shed antlers, fresh faecal pellets and tissues from dead animals, were analysed to access the genetic diversity of the KLNP deer population. It was established that the hog deer species of KLNP is genetically similar to the eastern sub-species of hog deer and not the western sub-species.
The study was done using mitochondrial DNA and the Microsatellite Marker technique to explain the genetic diversity and population structure of the hog deer species at KLNP. “We used mitochondrial DNA technique because of its advantages over other similar techniques,” said Gupta. “Mitochondrial DNA sequences, in all higher vertebrate progenies, come from the mothers. It carries certain unique features that help understand the genetic evolutionary process. It also survives the biological clock and this makes it very useful in checking the speciation process and time of diversion of a population or individual from the parent population. For phylogenetic and phylogeographic study, mitochondrial DNA marker is the most appropriate marker used across the globe.”
In order to compare the genetic sequence of the sample, the researchers downloaded the mitochondrial DNA sequence of the eastern hog deer from GenBank, an open-access annotated collection of all publicly available DNA sequences under the National Institute of Health, United States.
“After the analysis, we found out that the genetic distance between the KLNP population and the recognised Axis porcinus annamiticus of Southeast Asia was very low,” Gupta explained. “Moreover, the Indian hog deer population of Dudhwa National Park, Corbett National Park and Kaziranga National Park exhibits a high level of genetic diversity, whereas the KLNP hog deer population has a relatively low level of genetic diversity. This can be attributed to the loss of connectivity with the source population after the glacial period.”
The study not only revealed significant genetic divergence between the major Indian populations of hog deer and the KLNP population but also has estimated the divergence time of the KLNP deer population. According to the study, the major population of the hog deer in India split from the KLNP population around 0.22 million years ago. The main factor leading to the separation of the KLNP deer from the rest of the Indian population could be the geographical barrier in the form of the major Purvanchal mountain ridges that consist of the Garo, Khasi, Jalatia, Naga, Barail, and Mizo hills, the study said.
Need for upgrade in conservation status
The hog deer population in India is threatened by habitat alteration, fragmentation, and poaching, all of which have led to a drastic decline in its population. The western sub-species of hog deer is listed in Appendix III of the Convention on International Trade in Endangered Species of Wild Fauna and Flora, or CITES, a treaty signed by 21 countries to protect endangered plants and animals. The eastern hog deer sub-species population from Southeast Asia is listed in Appendix I. The population found in Manipur however, is still under Appendix III.
“Appendix I of the CITES lists the eastern sub-species of hog deer, present only in Southeast Asia. Now that our study has established that the KLNP population is the same as the one present in Southeast Asia, the KLNP population should also get included in Appendix I, keeping in mind the low genetic diversity and population size of this sub-species,” said Gupta. “Moreover, since the eastern hog deer population will soon make it into the Critically Endangered Category of the Red List, the KLNP population should get included too. There are hardly 100 deer of this sub-species in India and the number is dwindling further due to poaching.”
Gupta added that the Wildlife Institute of India study advocates more robust conservation practices for both Indian sub-species of hog deer.
Meanwhile, according to a population estimate by the forest department at the KLNP, the population of hog deer in 2018 was 288.
Though there is some variation in the population estimates by the forest department and researchers, the importance of conservation of the animal is highlighted by both. The status of the Indian hog deer was upgraded under the Indian Wildlife Protection Act, 1972, from Schedule III to Schedule I, which forbids hunting by more stringent rules.
Roughly 5,800 species of animals and 30,000 species of plants are protected by CITES against overexploitation through international trade. They are listed in the three appendices, according to the level of threat by international trade. They include some whole groups, such as primates, cetaceans (whales, dolphins and porpoises), sea turtles, parrots, corals, cacti and orchids. But in some cases, only a subspecies or geographically separate population of a species (for example the population of just one country) is listed.
Breeding programmes for saving populations
Researchers believe the hog deer population should be conserved with more focused effort, with a special focus on the KLNP population. “We should think on the lines of creating alternate homes for the eastern hog deer of KLNP. The population size can be increased with effective breeding programmes under captive condition and repopulating the species later,” said Gupta. “While a lot of attention is being given to the sangai, another deer species at KLNP, the hog deer species has been neglected. Saving the hog deer will help in conservation of sangai deer as well because both the species are sympatric.”
Two related species that once interbred and no longer do but continue to exist in the same geographic area and thus frequently encounter one another are considered to be sympatric.
The Wildlife Institute of India’s researchers plan to extend the scope of their study to include the genetic analysis of the hog deer population of Tripura and other areas bordering Bangladesh.
This article first appeared on Mongabay.