A "smiling" porpoise at the Wuhan Institute of Hydrobiology. （File photo/China Daily)
(ECNS) -- Recent research suggests that the critically endangered Yangtze finless porpoise should be considered a unique incipient species different from marine porpoises.
The research team led by Professor Yang Guang of Nanjing Normal University reported the sequencing, de novo assembly and analysis of a finless porpoise genome, and the re-sequencing of an additional 48 finless porpoise individuals, using the data to reconstruct the demographic history of finless porpoises from their origin to their occupation of the Yangtze River.
The report published on Nature Communication said analysis of marine and freshwater porpoise selections identifies genes associated with renal water homeostasis and urea cycles, which are likely adaptations associated with the difference in osmotic stress between ocean and rivers.
The team composed of Chinese and U.S. researchers suggested the Yangtze finless porpoise is reproductively isolated from other porpoise populations and harbors unique genetic adaptations.
The present findings of significant population differentiation, a lack of gene flow, and unique adaptive divergence in the Yangtze finless porpoise make it clear the Yangtze finless porpoise is genetically and reproductively isolated from its marine counterpart, said the report.
After it was identified as a new independent species, the Yangtze finlesss porpoise's Lantin name has been changed from Neophocaena asiaeorientalis asiaeorientalis into Neophocaena asiaeorientalis.
Yang told the Beijing News that the Yangtze finless porpoise lives in an area alongside a high population density, and that overfishing has dealt a deadly blow to biodiversity in China's longest river, causing the depletion of fishery resources and threatening the survival of the species.
There are only about 1,000 individuals of the finless, dolphin-like creature left in the wild, according to Yang.
Yang said that to make the creature a distinct endemic Chinese species will be beneficial for protection efforts, but there's still a long way to go to conserve the biodiversity and aquatic ecosystem of the Yangtze River.
Yangtze finless porpoises are considered critically endangered by the IUCN and may eventually become extinct if effective conservation measures are not urgently implemented, according to researchers.