Present-Day Evidence For Evolution “Observing Evolution In Action” Natural Selection • Is there any evidence of Natural Selection taking place in real populations? • One study, performed during the industrial revolution in England, demonstrated that populations of organisms ARE greatly affected by environmental changes The Peppered Moth • Two different forms of the moth existed • One Dark form, one Light • Both forms were common Natural Selection At Work • What kind of tree would you expect the Dark forms to sleep on? • What kind of tree would you expect the Light form to sleep on? The Effect Of A Changing Environment • What do you think might have happened to the • • • • trees that were near coal-burning factories and power stations? They became covered in black carbon soot What do you predict might then have happened to the moth populations in these areas? In heavily industrialized areas, the Light form of the moth almost disappeared, because of predation The Dark form became dominant in these areas because of Natural Selection Antibiotic Resistance • Because Bacteria reproduce so quickly, they represent excellent specimens for testing Natural Selection • Watch how quickly they can “evolve” because of Natural Selection… Natural Selection In The Galapagos • Remember Darwin’s Finches? What was Darwin’s theory about how they came to have different beak sizes? Adaptive Radiation • Darwin proposed that all the finches evolved from a • • • • • single ancestral species Each island had a slightly different environment, and unique plant species were dominant on each one Different plants produced seeds of different sizes, some large, some small Over time, the finches best-adapted for the available food on each island were produced the most offspring, and became the dominant type in each location Due to the distance between the islands, the finches became isolated and no longer bred easily with finches on other islands, leading to separate species each with a unique beak size (Speciation) This evolutionary process is called Adaptive Radiation Evolution in your lifetime. • Bacteria are evolving in your life time into new forms antibiotics does not kill. • Plants have evolved in the past few year into forms that herbicides such as roundup do not kill.