17-4 Patterns of Evolution

1
17-4 Patterns of Evolution
2
Evolution

• Macroevolution
• Big changes over long periods of time. Mammals
  replace Dinosaurs
• Microevolution
• Changes within a species.
• Allele frequency change

3
Macroevolution

• Extinction
• Adaptive radiation
• Convergent evolution
• Co-evolution
• Punctuated equilibrium
• Changes in developmental genes

4
Extinction

• Environment changes, species disappear
• Some species have variations allowing them to
  survive.
• Other species can no longer successfully
  compete for resources.
• Environmental collapse (asteroid) normal
  natural selection cant function.

5
Adaptive Radiation

• Single species or small group gives rise to
  diverse groups that live in different ways.

6
Convergent evolution

• Unrelated organisms look alike because they face
  similar environmental demands.
• Structures of similar function are analogous, not
  homologous.
• They do the same job but made up of parts that do
  not share a common ancestry.

shark
fish
Different Ancestors
Similar appearance Same Environment,
mammal
dolphin
7
Co-Evolution

• Process by which two species evolve in response
  to changes in each other over time.
• Plants and pollinators

8
Speed of evolution

• Gradualism
• Biological change that is slow
• and steady over time.
• Punctuated Equilibrium
• Change occur rapidly after a long
• period of being stable.

9
Developmental Genes

• Changes (mutations) in the genes that control
  early development can produce transformations in
  the organisms.
• Hox genes master control genes that guide
  development of major body structures in animals.