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Natural Selection The Beak of the Finch To download: Shift LeftClick PowerPoint 97 Please respect copyright on this material Sources of Information The Beak of the Finch Jonathan Weiner Vintage Books – Very readable Our Global Environment Anne Nadakavukaren Waveland Press Key Points Natural selection is operating NOW Small variations in inherited capabilities can make a big difference Environmental change can upset everything Homo sapiens is a NEW species with still unknown limits to its influence Equatorial Pacific Sea SurfaceTemperature El Nino Dec 97 Normal Dec 90 La Nina NOAA/PMEL Dec 88 Charles Darwin The Voyage of the Beagle 18311836 The Galapagos Islands 1835 Origin of Species 1859 Cactus Finches A new adaptation Daphne Major Darwin’s Finches Radiative Adaptation Measuring a Beak Key Points Natural selection is operating NOW Small variations in inherited capabilities can make a big difference Environmental change can upset everything Homo sapiens is a NEW species with still unknown limits to its influence Variation within a species Tough Seeds Caltrop Key Points Natural selection is operating NOW Small variations in inherited capabilities can make a big difference Environmental change can upset everything Homo sapiens is a NEW species with still unknown limits to its influence Equatorial Pacific Sea SurfaceTemperature El Nino Dec 97 Normal Dec 90 La Nina NOAA/PMEL Dec 88 Associations of El Nino Natural Selection in Action Accurate measurements, 1973 – Beak shape critical to survival – – Peter & Rosemary Grant + students Deep beak for tough seeds (drought) Shallow beak for soft seeds (wet) La Niña (1977, drought) favors deep beak – All softer seeds eaten, 80% mortality – Big males survive, offspring bigger beaks El Niño (1983, flood) favors shallow beak – No big seeds, small birds with small beaks survive Implications of Natural Selection External – – forcing selects for change rapid selection within variability mutations and hybrids increase possibilities Bacteria resistant to antibiotics Pests resistant to insecticides Control has unintended consequences Key Points Natural selection is operating NOW Small variations in inherited capabilities can make a big difference Environmental change can upset everything, even what we do not see Homo sapiens is a NEW species with still unknown limits to its influence
