The two remaining wild populations of the endangered Indian rhinoceros - A study based on DNA and its implications for management

Genetic differences between the two remaining wild populations of the endangered Indian rhinoceros (Rhinoceros unicornis)

Samuel Zschokke, Georg F.J. Armbruster, Sylvain Ursenbacher Bruno Baur
Biological Conservation, Volume 144, Issue 11, November 2011, Pages 2702-2709

Understanding the characterization of the genetic units within each species and their relationships to each other is of primary importance when it comes to the management of rare and endangered species.

The Indian rhinoceros (Rhinoceros unicornis) is an endangered species with a current population size of c. 2800 individuals. The researchers analyzed 26 individuals of known origin kept in captivity and 21 wild ranging individuals of the two remnant large wild populations in Assam (India) and Nepal.

Mitochondrial and microsatellite markers were used to determine whether the two geographically isolated populations show distinct patterns of genetic diversity, and whether the genetic diversity of the populations is influenced by past demographic bottlenecks.

The researchers identified 10 different mitochondrial D-loop haplotypes, of which 4 were specific to the Assam population (10 sequences examined) and 6 specific to the Nepal population (19 sequences).

Microsatellite analysis demonstrated a strong genetic differentiation between the Assam and Nepal populations and allowed to assign each individual to its origin with high confidence.

The analyses revealed the occurrence of a bottleneck in the Assam population much earlier than the reported bottleneck in 1908.  It also revealed that the Nepal population is a recent (probably post-glacial) colonization.

The researchers contend that their data suggests separate conservation programs (even for captive individuals) as long as the persistence of the entire species is not severely threatened. The two populations should be treated as separate management units. The microsatellite markers can also be used to determine the origin of confiscated material such as horns.