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Title:

Macroevolution

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Saltation: a discontinuous mutational change in 1 phenotypic ... horseshoe crab. Zigzag evolution. Zigzag evolution: changes fluctuate around a mean value ... – PowerPoint PPT presentation

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Title: Macroevolution


1
Macroevolution
2
Gradualism saltation
Gradualism large changes in phenotypic
characters have evolved through many slightly
different intermediate states Saltation a
discontinuous mutational change in 1 phenotypic
traits, usually of considerable magnitude
3
saltation
gradualism
4
(No Transcript)
5
Gradualism saltation
  • Gaps in the fossil record
  • Gaps are real
  • Gaps reflect inadequate fossil record

6
Gradualism
intermediates functional considerations fitness
effects of mutation genetic differences
7
Saltation
radiation stasis Goldschmidt - hopeful
monster Eldredge Gould - punctuated equilibrium
8
Adaptive radiation
Adaptive radiation single or small group of
ancestral species rapidly diversify into a large
number of descendent species that occupy a wide
variety of ecological niches
9
Adaptive radiation
10
Adaptive radiation
Hawaiian honeycreepers
11
Living fossils
horseshoe crab
12
Zigzag evolution
Zigzag evolution changes fluctuate around a mean
value
13
Punctuated equilibrium
Punctuated equilibrium - rapid evolutionary
change followed by long periods of stasis
Niles Eldredge
Stephen J Gould
14
Rates of evolutionary change
gradualism
punctuated equlibrium
15
Stasis
bryozoans
16
Punctuated equilibrium criticisms
evolution by jerks populations can evolve
without speciating stable lineages are not
absolutely static most fossil sequences
incomplete during which characters can evolve
substantially selection within species is
quicker than speciation and extinction
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