Natural Selection The Beak of the Finch PowerPoint 97 To download: ShiftLeftClick Please respect copyright on this material

Sources of Information F The Beak of the Finch Jonathan Weiner Vintage Books – Very readable F Our Global Environment Anne Nadakavukaren Waveland Press

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

Equatorial Pacific Sea SurfaceTemperature F El Nino F Normal F La Nina Dec 97 Dec 90 Dec 88 F NOAA/PMEL

Charles Darwin F The Voyage of the Beagle F The Galapagos Islands 1835 F Origin of Species 1859

Cactus Finches F A new adaptation

Daphne Major

Darwin’s Finches Radiative Adaptation

Measuring a Beak

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

Variation within a species

Tough Seeds Caltrop

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

Equatorial Pacific Sea SurfaceTemperature F El Nino F Normal F La Nina Dec 97 Dec 90 Dec 88 F NOAA/PMEL

Associations of El Nino

Natural Selection in Action F Accurate measurements, – Peter & Rosemary Grant + students F Beak shape critical to survival – Deep beak for tough seeds (drought) – Shallow beak for soft seeds (wet) F La Niña (1977, drought) favors deep beak – All softer seeds eaten, 80% mortality – Big males survive, offspring bigger beaks F El Niño (1983, flood) favors shallow beak – No big seeds, small birds with small beaks survive

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

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