Transcript Homo sapiens

Natural Selection
The Beak of the Finch
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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