Evolution Notes
1) Historical background (p 506)
2) Development of Darwin’s ideas about evolution (p 507)
3) What are the lines of evidence?
1. Age of the earth should be ‘old’
2. Fossil evidence: change in composition; simple to more complex; increasing
diversity (p 518; 586)
3. Morphology, physiology, biochemistry and genetics should all reflect an evolutionary
tree: closely related spp. share most characteristics (p 516; 527)
4. Existence of intermediate forms
5. Populations of species should change (adapt) as conditions change (p 511)
6. Biogeographical distributions should reflect evolutionary history (p 518)
4) How do new species form?
• Causes of speciation – geographical isolation, reduction of gene flow, reproductive
barriers (p566)
• Modes of speciation – allopatric, peripatric, sympatric, and parapatric (p 569)
• Co-speciation
5) What are the mechanisms of evolution?
• Natural selection; descent and heredity
• Genetic variation – mutations, gene flow, and sexual reproduction (p 554)
• Genetic drift – founder effect, bottleneck effect (p 552)
• Co-evolution (p 885)
• Sexual selection (p 557; 573)
6) Macroevolution (Chapter 25)
• Patterns in macroevolution
o Stasis
o Character change
o Lineage splitting (p 578)
o Extinction (p 598)
• Patterns in development
o Changes in rate and timing (heterochrony) – allometric growth; peadomorphism
(p 602)
o Changes in spatial pattern (homeotic genes) (p 497; 603)
7) Modern views and arguments
,Historical Background and
Development of Darwin’s ideas
about evolution:
Aristotle 384-322 BC naturalistic model (vs supernatural intervention)
• Greatly influenced western science
• He studied nature and deduced that all living things could be arranged on a scale of
increasing complexity. “scale of nature”= Scala natural
• Each form was Perfect and permanent; and had a specific space on his scale.
Nasīr al-Dīn Tūsī (1201-1274)
• Persian scholar and polymath
• Put forward a basic idea of evolution ~600 years before Darwin was born
• "The organisms that can gain the new features faster are more variable. As a result, they
gain advantages over other creatures. [...] The bodies are changing as a result of the
internal and external interactions.
Charles Darwin’s theory of Evolution by Natural Selection
• Underlies all modern biology.
• Published 1859 Mechanism for evolution (descent with modification) is natural selection
CENTRAL IDEA OF BIOLOGICAL EVOLUTION:
All life on Earth shares a common ancestor
Through process of descent with modification, the common ancestor diversity of Life on
earth.
1. Life has a history i.e. it changed over time
2. Different species share common ancestors
, Key players who influenced thinking about evolution:
Carl von Linne (Linnaeus)- Swedish Botanist
• Founder of taxonomy.
• Developed the binomial system of naming species (spp), and a system by which similar
species were placed in a genus, similar genera in a family, similar families in orders etc.
George Cuvier (1769-1832) - French palaeontologist
• Developed the study of fossils (palaeontology)
• Recognised that fossils were evidence of earlier life forms. Observed changes in fossils in
different rock strata.
• Catastrophism: Believed that there must have been successive catastrophies (flood/
drought)
that wiped out most forms of life
Charles Lyell (1797-1875)- British geologist.
• Promoted idea of uniformitarianism i.e. most geological features are caused by slow,
gradual changes- not catastrophic events; e.g. earth’s surface sculpted by earthquakes,
volcanoes…
• Laws of nature have been constant over time -- so that we can use modern, observable
phenomena to explain past events.
Jean Baptiste de Lamarck (1744-1829)– French scientist
• Recognition that species change through time in response to their environment
• Characteristics passed from generation to generation
• Proposed a mechanism for the process of evolution
• Suggested that species are plastic and can be modified in response to the environment
• Promoted idea of gradualism
• His ideas that organisms strive for perfection and that complexity is achieved by will is
not accepted today (use and disuse theory) as acquired traits are not passed on
Thomas Malthus – British political economist
1) Historical background (p 506)
2) Development of Darwin’s ideas about evolution (p 507)
3) What are the lines of evidence?
1. Age of the earth should be ‘old’
2. Fossil evidence: change in composition; simple to more complex; increasing
diversity (p 518; 586)
3. Morphology, physiology, biochemistry and genetics should all reflect an evolutionary
tree: closely related spp. share most characteristics (p 516; 527)
4. Existence of intermediate forms
5. Populations of species should change (adapt) as conditions change (p 511)
6. Biogeographical distributions should reflect evolutionary history (p 518)
4) How do new species form?
• Causes of speciation – geographical isolation, reduction of gene flow, reproductive
barriers (p566)
• Modes of speciation – allopatric, peripatric, sympatric, and parapatric (p 569)
• Co-speciation
5) What are the mechanisms of evolution?
• Natural selection; descent and heredity
• Genetic variation – mutations, gene flow, and sexual reproduction (p 554)
• Genetic drift – founder effect, bottleneck effect (p 552)
• Co-evolution (p 885)
• Sexual selection (p 557; 573)
6) Macroevolution (Chapter 25)
• Patterns in macroevolution
o Stasis
o Character change
o Lineage splitting (p 578)
o Extinction (p 598)
• Patterns in development
o Changes in rate and timing (heterochrony) – allometric growth; peadomorphism
(p 602)
o Changes in spatial pattern (homeotic genes) (p 497; 603)
7) Modern views and arguments
,Historical Background and
Development of Darwin’s ideas
about evolution:
Aristotle 384-322 BC naturalistic model (vs supernatural intervention)
• Greatly influenced western science
• He studied nature and deduced that all living things could be arranged on a scale of
increasing complexity. “scale of nature”= Scala natural
• Each form was Perfect and permanent; and had a specific space on his scale.
Nasīr al-Dīn Tūsī (1201-1274)
• Persian scholar and polymath
• Put forward a basic idea of evolution ~600 years before Darwin was born
• "The organisms that can gain the new features faster are more variable. As a result, they
gain advantages over other creatures. [...] The bodies are changing as a result of the
internal and external interactions.
Charles Darwin’s theory of Evolution by Natural Selection
• Underlies all modern biology.
• Published 1859 Mechanism for evolution (descent with modification) is natural selection
CENTRAL IDEA OF BIOLOGICAL EVOLUTION:
All life on Earth shares a common ancestor
Through process of descent with modification, the common ancestor diversity of Life on
earth.
1. Life has a history i.e. it changed over time
2. Different species share common ancestors
, Key players who influenced thinking about evolution:
Carl von Linne (Linnaeus)- Swedish Botanist
• Founder of taxonomy.
• Developed the binomial system of naming species (spp), and a system by which similar
species were placed in a genus, similar genera in a family, similar families in orders etc.
George Cuvier (1769-1832) - French palaeontologist
• Developed the study of fossils (palaeontology)
• Recognised that fossils were evidence of earlier life forms. Observed changes in fossils in
different rock strata.
• Catastrophism: Believed that there must have been successive catastrophies (flood/
drought)
that wiped out most forms of life
Charles Lyell (1797-1875)- British geologist.
• Promoted idea of uniformitarianism i.e. most geological features are caused by slow,
gradual changes- not catastrophic events; e.g. earth’s surface sculpted by earthquakes,
volcanoes…
• Laws of nature have been constant over time -- so that we can use modern, observable
phenomena to explain past events.
Jean Baptiste de Lamarck (1744-1829)– French scientist
• Recognition that species change through time in response to their environment
• Characteristics passed from generation to generation
• Proposed a mechanism for the process of evolution
• Suggested that species are plastic and can be modified in response to the environment
• Promoted idea of gradualism
• His ideas that organisms strive for perfection and that complexity is achieved by will is
not accepted today (use and disuse theory) as acquired traits are not passed on
Thomas Malthus – British political economist
