How species change

1
How species change

• More about the finches

2
Darwins Finches

• 13 different species of finches
• Darwin though they were different species of
  wren, warbler, blackbirds and so on.
• Identified as finches in England
• Beaks are specialized for the bird to eat
  different food
• Some birds use their beaks to make tools
• Some are vampires
• Look at page 254 in the textbook

3
Natural selection

• The different beaks are useful when the dry
  season occurs (Darwin visited in rainy season)
• The birds become feeding specialist when food is
  scarce
• Beak specialization lets the birds optimize the
  search for scarce food
• Modern biologists today tag the birds and follow
  them
• In drought 1976-1977 biologists saw natural
  selection at work