MAPPING THE BIG CAT

Ateam of researchers from Stanford, NCBS et al sequenced 65 genomes from four subspecies—Amur, Bengal, Sumatran and Malayan—over three years. The four were found to be genetically distinct. Indian tigers as a whole had the highest genetic variation, but some of them show signs of possible inbreeding. Even Bengal tigers, which comprise about 70 per cent of the world’s wild tigers and exhibit relatively high genomic diversity compared to other subspecies, showed signs of inbreeding in some populations. Tigers from the Northeast were the most different from other populations in India. Extreme fragmentation and high human population density in India has resulted in isolated populations, where individuals may be more likely to mate with relatives. In contrast, despite low Amur tiger population densities in the Russian Far East, individual movement is not hindered by significant barriers and there is less inbreeding. Despite this, and other adaptations, Amur and Sumatran tigers have lower genetic diversity, so if populations continue to decline, genetic rescue may be needed.