Research Article: Luo, S. J., Kim, J. H., Johnson, W. E., van der Walt, J., Martenson, J., Yuhki, N., Miquelle, D. G., Uphyrkina, O., Goodrich, J. M., Quigley, H. B., Tilson, R., Brady, G., Martelli, P., Subramaniam, V., McDougal, C., Hean, S., Huang, S. Q., Pan, W., Karanth, U. K., Sunquist M., Smith, J. L. D., O’Brien, S. J. (2004). Phylogeography and genetic ancestry of tigers (Panthera tigris). PLOS Biology, 2(12), e442.

Blog Author: Dhanush Shetty

Key Takeaways:

  • Tigers are a globally recognized big cat admired for their beauty and strength. Unfortunately, tigers are endangered due to factors such as, habitat loss, hunting, and poaching.
  • The research article states that the number of Bengal tigers (P.t. tigris) are estimated between 3,200 – 4,500. The Bengal tiger is one subspecies of tigers.
  • Research using molecular data found that tigers are divided into six subspecies that diverged 110,000 years ago due to climate change and sea level fluctuations.
  • Different subspecies have varying levels of genetic diversity and geographic barriers like the Himalayas and Sundaland which have contributed to their divergence.
  • Human activities like habitat destruction and hunting have also impacted the genetic diversity and population structure of tigers.
  • Preserving the genetic diversity and unique evolutionary histories of subspecies and protecting geographic barriers is crucial for tiger conservation.
  • Maintaining connectivity between tiger populations is also important to prevent further loss of genetic diversity and to promote population recovery.

Tigers are big cats that are recognized worldwide. They are also admired for their beauty and strength, but unfortunately, tigers face serious threats. Tigers are facing a decline in their population size and range due to various factors such as loss of habitat, hunting, and poaching. The research article states that the number of Bengal tigers (P.t. tigris) are estimated between 3,200 – 4,500. The Bengal tiger is one subspecies of tigers.

To better understand the genetic diversity of tigers, researchers used molecular data from mitochondrial DNA and microsatellite loci (microsatellite loci are repeating sequences of DNA that act as a unique genetic signature used to distinguish between individuals, species or populations) to investigate the genetic relationships between different populations of tigers across their range. They found that tigers are divided into six subspecies, and diverged from each other around 110,000 years ago. The most ancient subspecies is the Bengal tiger, and the most recent subspecies is the Sumatran tiger. The researchers hypothesized that the subspecies’ divergence was influenced by climate change and fluctuations in sea levels.

The researchers also found that the different subspecies have different levels of genetic diversity. This means that some subspecies have more genetic variation than others. Some subspecies have clear genetic differences, while others have genes that flow between them. The researchers identified several geographic barriers that have contributed to the divergence of tiger populations. One of the most significant barriers is the Himalayan mountain range, which separates the Indian subcontinent from the rest of Asia. Tigers from India and Nepal are genetically distinct from those in Southeast Asia and China due to the presence of the Himalayas. The researchers also found that the Sundaland region, which includes the Indonesian islands of Sumatra, Java, and Bali, has acted as a barrier to gene flow between tigers in this region and those in mainland Asia.

Human activities, such as habitat destruction, hunting, and poaching have also had a significant impact on the genetic diversity and population structure of tigers. For example, the Indochinese tiger has experienced a severe population bottleneck (a situation where a large population of organisms is reduced in size) and loss of genetic diversity due to hunting and habitat loss.

The researchers highlight the importance of preserving the genetic diversity and unique evolutionary histories of the different subspecies of tigers, as well as the need to protect the geographic barriers that have contributed to their divergence. They also stress the importance of maintaining connectivity between tiger populations to prevent further loss of genetic diversity and to promote population recovery. Thus showing important implications for the conservation of tigers.

You can access the original article here.

Keywords: Tiger, Population genetics, Phylogenetic analysis, Mitochondrial DNA, Genetic loci, Haplotypes, Phylogeography