The phrase "species barrier" refers to a limit or obstacle that prevents different species from easily interacting or transmitting diseases to each other. Full definition
These experimental combinations of genes cross the natural species barrier and have not been proven safe. (earthmamaorganics.com)
Annette Cotter: GE — or manipulation of organisms at a genetic level by crossing species barriers is an inherently risky business. (globaleducationmagazine.com)
«For these viruses to jump species barriers they need a lucky genetic mutation combined with significant fluid exchange. (cam.ac.uk)