Researchers from the Indian Institute of Science (IISc), Bengaluru, have announced that the ancestors of the blackbuck (Antilope cervicapra) came into India from the Saharo-Arabian region about two million years ago and then developed to its current form, according to a report in September 2019.
Studying four genera of ‘true antelopes’—Gazella, Nanger, Eudorcas and Antilope, they compared the divergence dates of the blackbuck to the biogeographical conditions in India. They have stated that the antelopes were part of the fauna that came in through the northwest gateway into India. The lack of blackbuck fossils outside India has led them to speculate that the blackbucks diverged from their ancestors only after reaching India, long after the intensification of aridification in the Indian subcontinent. The expansion of grasslands following that period opened up new niches, which could have facilitated the divergence of many taxa. The formation of the Thar desert could have been a barrier to the back-dispersal of the grassland-based blackbucks.
The paper, published in Molecular Phylogenetics and Evolution, states that blackbucks have been confined to the scrubland regions of India, currently seen in most states, except for the Terai region, northeast and the Western Ghats. In the south, blackbucks can be seen up to the Tirunelveli district in Tamil Nadu.
The team noted that Antilope was not a sister of Gazella, as was previously believed, but was within the same genera. So Antilope should be reassigned as a species under Gazella. Members of the Gazella genus have certain morphological characters, which were not seen in Antilope, so they were put under a separate genus. But molecular studies have shown that the characteristics are not entirely different.
Researchers generally use mitochondrial DNA for genetic analysis, but these researchers used nuclear DNA, which has genetic material from both parents. They used 12 different nuclear markers for the study. It was observed that there are differences in the mitochondrial-DNA and nuclear-DNA trees, and so therefore, there are conflicts between molecular data also. Taxonomical studies may combine use of both molecular and morphological analysis, according to the team.
Chinkara It was stated that the chinkara (Gazella bennetti), also called Indian gazelle and considered another ‘true antelope’ of India, could be traced to about 7,00,000 years ago. These are also found in the hilly terrains of Iran (Iranian Gazelle). Being facultative drinkers, they were better adapted to the drier, semi-arid region of the Thar desert. Though the blackbuck and chinkara are considered related, it may be that they actually have very different histories.