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Chapter 4: Speciation and Phylogeny

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Chapter 4: Speciation and Phylogeny Macroevolution Species and Speciation Phylogenies: Evolutionary Trees Biological Species Reproductive isolation Gene flow within ... – PowerPoint PPT presentation

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Title: Chapter 4: Speciation and Phylogeny


1
Chapter 4 Speciation and Phylogeny
  • Macroevolution
  • Species and Speciation
  • Phylogenies Evolutionary Trees

2
Biological Species
  • Reproductive isolation
  • Gene flow within species
  • No gene flow between species
  • Allopatric speciation results from
    geographic/environmental isolation
  • Selection or gene drift will eventually change
    each population in different directions and
    eventually they will be incapable of
    interbreeding

3
  • Sympatric Speciation Niche diversification
  • Different ways of making a living in the same
    place.
  • Specialization toward different resource
    gathering strategies leads to different selective
    forces

4
  • Sympatric Speciation Niche diversification
  • Different ways of making a living in the same
    place.
  • Specialization toward different resource
    gathering strategies leads to different selective
    forces

5
  • Darwins finches
  • Adaptive radiation
  • Other isolation mechanisms
  • Mechanical isolation
  • Temporal isolation
  • Behavioral isolation
  • Seagulls around the World

6
Phylogenies Trees of Life
  • Linnaeus Linnaean System of Classification
  • Based on similarity of traits
  • Hierarchical
  • Kingdom
  • Phylum
  • Class
  • Order
  • Family
  • Genius
  • Species
  • Kings Play Chess On Fine Grained Sand
  • Keep Pots Clean Or Family Get Sick

7
Humans are
Kingdom Animal Phylum Cordates (Sub phylum
Vertebrata) Class Mammal Order Primate Family H
ominid (Super Family Hominoid) Genius Homo Species
Sapiens
8
Phylogeny for the Hominoids
9
Inheritance or Convergence?
  • Homologous Similar because of common decent
    (share a recent common ancestor) Inheritance.
  • Analogous Similar because of adaptation to the
    same or similar environmentally stable problem
    (Bird and Bat wings) - Convergence.

10
Phylogenies use homologous structures (traits)
and must avoid analogous structures
Present Past
11
Yes
No
No
Derived Trait Analogous Trait
Ancestral Trait (last common ancestor)
(convergence) (common ancestor
of all 3)
12
Using Overall Similarity of Traits Leads to the
Wrong Family Tree
13
Using Similarity of Derived Traits Leads to the
Correct Family Tree
14
Using Similarity of Derived Traits Leads to the
Correct Family Tree
15
Systematics the study that distinguishes
ancestral from derived traits
  • Ancestral Traits
  • Appear earlier in embryonic development
  • Ontology recapitulates phylogeny
  • Appear earlier in the fossil record
  • Older traits
  • Seen in out-groups
  • If a trait is absence in one species but seen in
    other more distant lineages (tails)

16
Genetic Distance
  • DNA Hybridization

Less Related More Related
Fewer bonds More bonds
Lower Temp to break Higher Temp to break
17
Molecular Clock
Neutral theory or Natural selection?
18
How Good are Human Phylogenies
  • Cladistic modeling of skeletal traits do not
    match the cladistic modeling of DNA distance
  • Human phylogenies are based on skeletal data and
    are likely to have errors. Some argue for
    Bastian statistics approach.
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