Begegnungen mit der Natur 8, Arbeitsheft

27 Mechanismen der Evolution How about using English – Natural selection In the nineteenth century Charles Darwin suggested the idea of evolution by natural selection: only the best adapted organisms survive and pass their genes on to the next generation. A recent example that demonstrates natural selection is Biston betularia . This peppered moth flies by night. At the daytime it rests on birch-trees. The light coloured tree trunks camouflage the moth very effectively. Suddenly, in 1849 a black form of Biston betularia appeared near Manchester. The reason was a mutation from a normal allele to one which causes the black colour. This mutation happened very often, but because the light coloured tree trunks did not hide the dark moths most of them had been eaten by birds. By 1900, 98 % of the moths near Manchester were black. How can we explain this fact? Caused by the pollution of the environment during the Industrial Revolution many trees were covered in soot. Therefore, the dark moths were better camouflaged and the light ones had been eaten by birds. Schulbuch Seite 88–89 O  Light coloured surfaces camouflage the peppered moth very effectively. The black moth is better camouflaged on a polluted tree trunk.  Put the correct text under the pictures.  In 1849 a black form of Biston betularia appeared.  The dark ones had been better adapted so more of them survived.  The light coloured tree trunks did not hide the dark moth so most of them had been eaten by birds.  When many trees were covered in soot, the dark moths were better camouflaged.  The light coloured trunks of the birch-trees camouflage the peppered moth Biston betularia very effectively.  In this environment the light moths had been eaten by birds. Nur zu Prüfzwecken – Eigentum d s Verlags öbv