Gene changes made ‘ river pig’ unique

Paris: April 10: China's critically endangered Yangtze River porpoise is a distinct species, meaning it cannot interbreed with other porpoise types to pass on its DNA, a major analysis of the creature's genome revealed on Tuesday.

The finless, dolphin- like creature, which sports a permanent, almost human grin on its snubnosed face, is the world's only freshwater porpoise.

But there are only about 1,000 individuals left in the wild — a number shrinking by 14 percent per year — and conservationists warn the critter is poised to follow the longsnouted Yangtze River dolphin, or baiji, into extinction.

For the latest study, intended to spur conservation efforts, an international research team analysed the genome of the Yangtze River porpoise and compared it to 48 other finless porpoises from different regions.

The exercise revealed that the animal known as “river pig” in China was a “distinct” species and “genetically isolated from other porpoise populations”, the experts wrote in the journal Nature Communications.

The new data showed the three main groups had, in fact, “not shared gene flow for thousands of years”, the study said.

And each group shows “unique, individualised signatures of genetic adaptation to different environments.”

In Nature, cross- species mating results in sterile offspring, if any at all. No such obstacles exist for mating between members of two sub- species.