Genome sequence of China's extinct dolphin published

Chinese scientists on Wednesday published the genome sequence of the Yangtze River dolphin, an iconic freshwater mammal of China driven to extinction by human activity.

A paper published in online scientific journal Nature Communications describes the study by Yang Guang at Nanjing Normal University and his colleagues, who sequenced the genome of a male dolphin and resequenced three additional genomes.

A genome is the genetic material contained within an organism.

"Studying the genome sequence of the Yangtze River dolphin is important to understanding the cetaceans' evolution and adaptation to aquatic life, and the reasons behind the dolphin's extinction," Yang said.

Nicknamed the "Goddess of the Yangtze," the dolphin otherwise known as "baiji" is one of the four known river dolphin species in the world. It was declared extinct in 2006, which means the population is too small for species' reproduction.

Conservationists have blamed baiji's demographic decline on pollution and increased human activities on the Yangtze, China's longest waterway and the mammal's only habitat.

Yang said the study showed a low genetic variability in baiji, which might be caused by a population bottleneck that happened some 10,000 years ago due to climate change and the rise of sea levels.

However, the baiji population rebounded afterwards, suggesting that human interference, rather than its genetic flaws, is to blame for the species' extinction, Yang said.