1. Origin of Species
Unit 6.5

3. Population whose members can interbreed
WHAT IS A SPECIES?
Defined by Ernst Mayr
Population whose members can interbreed
AND produce viable, fertile offspring
TWO DISTINCT SPECIES Body and coloration are similar . . .
but their songs and other behaviors are different enough
to prevent interbreeding

4. In the wild lions and tigers don’t interbreed
but in zoos… can get hybrids
Largest cat in world
. . . but male ligers are sterile
LIGER - Male lion X female tiger
TIGON- Male tiger X female lion

10. Blue Footed Booby dance

17. Hybrid

21. (DIVERGENT EVOLUTION)

25. CURRENT DEBATE NOT over whether evolution happens
… overwhelming evidence here!
BUT . . .Does speciation happen gradually OR rapidly in response to environmental change?
GRADUALISM
Change happens slowly
“Baby steps” over long
Periods of time
CHARLES DARWIN
CHARLES LYELL

26. PUNCTUATED EQUILIBRIUM
Niles Eldredge- Curator American Museum of Natural History
TIME
Rate of speciation is NOT CONSTANT
Rapid change when 1st split from parent
population
Unchanging for long periods
Stephen Jay Gould ( ) Paleontologist/evolutionary biologist