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Natural Selection The Beak of the Finch PowerPoint 97 To download: ShiftLeftClick Please respect copyright on this material Slide 2 Sources of Information F The Beak of the Finch Jonathan Weiner Vintage Books Very readable F Our Global Environment Anne Nadakavukaren Waveland Press Slide 3 Key Points F Natural selection is operating NOW F Small variations in inherited capabilities can make a big difference F Environmental change can upset everything F Homo sapiens is a NEW species with still unknown limits to its influence Slide 4 Equatorial Pacific Sea SurfaceTemperature F El Nino F Normal F La Nina Dec 97 Dec 90 Dec 88 F NOAA/PMEL Slide 5 Charles Darwin F The Voyage of the Beagle 1831- 1836 F The Galapagos Islands 1835 F Origin of Species 1859 Slide 6 Cactus Finches F A new adaptation Slide 7 Daphne Major Slide 8 Darwins Finches Radiative Adaptation Slide 9 Measuring a Beak Slide 10 Key Points F Natural selection is operating NOW F Small variations in inherited capabilities can make a big difference F Environmental change can upset everything F Homo sapiens is a NEW species with still unknown limits to its influence Slide 11 Variation within a species Slide 12 Tough Seeds Caltrop Slide 13 Key Points F Natural selection is operating NOW F Small variations in inherited capabilities can make a big difference F Environmental change can upset everything F Homo sapiens is a NEW species with still unknown limits to its influence Slide 14 Equatorial Pacific Sea SurfaceTemperature F El Nino F Normal F La Nina Dec 97 Dec 90 Dec 88 F NOAA/PMEL Slide 15 Associations of El Nino Slide 16 Natural Selection in Action F Accurate measurements, 1973 - Peter & Rosemary Grant + students F Beak shape critical to survival Deep beak for tough seeds (drought) Shallow beak for soft seeds (wet) F La Nia (1977, drought) favors deep beak All softer seeds eaten, 80% mortality Big males survive, offspring bigger beaks F El Nio (1983, flood) favors shallow beak No big seeds, small birds with small beaks survive Slide 17 Implications of Natural Selection F External forcing selects for change rapid selection within variability mutations and hybrids increase possibilities F Bacteria resistant to antibiotics F Pests resistant to insecticides F Control has unintended consequences Slide 18 Key Points F Natural selection is operating NOW F Small variations in inherited capabilities can make a big difference F Environmental change can upset everything, even what we do not see F Homo sapiens is a NEW species with still unknown limits to its influence