Heavy metals such as zinc, lead and copper interfere with an organisms normal functioning by attaching themselves to proteins and DNA. Heavy metals are rare under natural conditions, so most plants and animals have never adapted to them and thus do not tolerate them. Because of human activity, heavy metals in high concentrations are more common. Plants and animals must adapt to these heavy metals or face extinction.
Another example of evolutionary change induced by human pursuits discussed in the book Darwin Comes to Town by Menno Schilthuizen is the adaptation of yellow monkey flower (Mimulus guttatus) to copper. At the Copperopolis copper mine in California, yellow monkey flowers survive on copper-rich slag heaps. This copper tolerance is due to a single gene mutant which appears to help the cells flush out copper atoms.
M.R. NcNair and his associates showed a similar single-gene modification in copper tolerant yellow monkey flowers from Northern Wales.
Yellow monkey flowers are native to Western North America but since the early 19th Century have become naturalized in Europe and Great Britain. Other common names for yellow monkey flower are common monkey flower and seep monkey flower. A synonym for M guttatus is Erythranthe guttatus.
More information about yellow monkey flower can be found in my previous post “Yellow Monkey Flower” on 08-04-2011. These yellow monkey flowers were photographed along Spring Creek in Collier Park (Oregon) in July.