Genes jump across species boundaries
In "horizontal gene transfer" individuals exchange their genetic material with each other without reproducing. The phenomenon is known from microorganisms, but more and more studies show that it also occurs in vertebrates, surprisingly often.
In the cold waters of the polar regions, marine life has developed various mechanisms to deal with the low temperatures. The ability to form anti-freezing proteins (AFPs), which prevent the growth of destructive ice crystals in blood, body tissues and cells, is widespread. This trait has evolved independently on multiple occasions-in fish, plants, fungi, and bacteria.
Not surprising at first, then, that herring (Clupeidae) and smelt (Osmeridae), two families of fish that are abundant in the North Atlantic and North Pacific, both produce AFP. On closer inspection, however, it is surprising that they use the same gene for this. The lineages of the two families diverged more than 250 million years ago, and more closely related groups do not have the corresponding genes.
A team led by Laurie Graham from Queen's University (Canada) has found a sensational explanation for this. According to the thesis, the gene migrated from the herring genome directly into the smelt genome - and without sexual union, because these groups are unable to interbreed with each other, as numerous experiments have shown. The hereditary disposition has thus been transmitted in a non-sexual way …