@Suchhund Das Beispiel mit dem Birkenspanner ist mir geläufig, in meinem Link ging es aber um beobachtbare Artbildung, das geht weit über das Beispiel des Birkenspanners hinaus.
"...Purple Salsify or Oyster Plant, Tragopogon porrifoliusFor example, there were the two new species of American goatsbeards (or salsifies, genus Tragopogon) that sprung into existence in the past century. In the early 1900s, three species of these wildflowers – the western salsify (T. dubius), the meadow salsify (T. pratensis), and the oyster plant (T. porrifolius) – were introduced to the United States from Europe. As their populations expanded, the species interacted, often producing sterile hybrids. But by the 1950s, scientists realized that there were two new variations of goatsbeard growing. While they looked like hybrids, they weren’t sterile. They were perfectly capable of reproducing with their own kind but not with any of the original three species – the classic definition of a new species...."
Ganzer, übrigens sehr interessanter Artikel unter
http://scienceblogs.com/observations/2010/04/24/evolution-watching-speciation/ (Archiv-Version vom 21.04.2014)Das ist ein gutes Beispiel für evolutionäre Artbildung. Das Besondere ist, dass es sich in unserer Zeit abspielt und das es beobachtbar ist.