Lichen

Another interesting observation supporting evolution by natural selection comes from England. In a collection of moths made in 1850s,i.e., before industrialisation set in, it was observed that there were more white-winged moths on trees than dark-winged or melanised moths. However, in the collection carried out from the same area, but after industrialisation, i.e., in 1920, there were more dark-winged moths in the same area, i.e., the proportion was reversed. The explanation put forth for this observation was that ‘predators will spot a moth against a contrasting background’. During post-industrialisation period, the tree trunks became dark due to industrial smoke and soot. Under this condition the white-winged moth did not survive due to predators, dark-winged or melanised moth survived. Before industrialisation set in, thick growth of almost white-coloured lichen covered the trees - in that background the white winged moth survived but the dark-coloured moth were picked out by predators.