COLD SPRING HARBOR, N.Y. — When different species mate and produce hybrid babies, the result can be an evolutionary dead end or an entirely new species. New research is revealing the molecular details leading toward a new evolutionary route or back toward the parental species.
Even though some hybrid offspring — such as mules — are sterile, many pairs of species can produce fertile hybrids. That doesn’t necessarily mean the birth of new hybrid species, as evolutionary geneticist Molly Schumer of Princeton University and her colleagues have discovered.