The Macroevolutionary Puzzle

1
The Macroevolutionary Puzzle

• Starr/Taggarts
• Biology
• The Unity and Diversity of Life, 9e
• Chapter 20

2
Key Concepts

• All species that have ever lived are related
• Macroevolution refers to patterns, trends, and
  rates of change among lineages over geologic time
• Fossil and geologic records and radiometric
  dating of rocks provide evidence of macroevolution

3
Key Concepts

• Anatomical comparisons help reconstruct patterns
  of change through time
• Biochemical comparisons also provide evidence of
  macroevolution
• Diversity characterizes the distribution of
  species through time
• Taxonomy is concerned with identifying and naming
  new species

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Fossils Evidence of Ancient Life

• Fossilization is slow process
• Stratification
• Layering of sedimentary deposits
• The older the layer, the older the fossils
• Geologic Time Scale
• Based on sequences of fossils in sedimentary
  rocks

5
Comparative Morphology

• Comparison of body forms and structures
• Morphological divergence
• Change from body form of a common ancestor
• Morphological convergence
• Body parts in remote lineages become similar
  under similar selection pressures

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Comparative Morphology

• Homology
• Similarity in body parts in different organisms
• Attributable to descent from a common ancestor
• Analogy
• Similarity in body parts in different organisms
• Attributable to similar environmental pressures

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Homologous Structures

• Vertebrate forelimbs

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Comparative Embryology

• Early vertebrate embryos strongly resemble one
  another
• Same plan of development

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Changes in timing of developmental steps

• Skull bones of chimpanzee and human
• Changes in growth rate timing of developmental
  steps

10
Evidence from Comparative Biochemistry

• Molecular clocks
• Neutral mutations
• Protein comparisons
• Cytochrome C
• Nucleic Acid comparisons
• Base-pairing of DNA or RNA from one species to
  another

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Identifying SpeciesPast and Present

• Taxonomy
• Assigning species names
• Binomial system
• Genus and Species
• Higher Taxa
• Family, Order, Class, Phylum, and Kingdom

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Finding Evolutionary Relationships Among Species

• Classical systematics
• Cladisitics

13
How Many Kingdoms?

• Whittakers Five-Kingdom Scheme
• Monera
• Protista
• Fungi
• Plantae
• Animalia

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Six Kingdom Scheme

• Carl Woese
• Includes the Archaebacteria

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Three Domain Scheme

• Favored by microbiologists
• Eubacteria
• Archaebacteria
• Eukaryotes

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A Changing Earth

• Plate tectonics
• Theory that plates of the Earths crust float on
  the underlying mantle
• Plates are in motion and have rafted continents
  to new positions over time
• Early supercontinents
• Gondwana
• Pangea

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Radiometric Dating

• Half-life
• Time it takes for one half of a given quantity
  of a radioisotope to decay into a daughter isotope

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In Conclusion

• Macroevolution is the study of patterns, trends,
  or rates of change among groups of species over
  long periods of time
• There is extensive evidence of evolution based on
  similarities and differences in body form,
  function, behavior, and biochemistry
• Completeness of fossil records are variable
• Fossil and geologic record show that such changes
  have influenced evolution

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In Conclusion

• Comparative morphology reveals similarities in
  embryonic development and identified homologous
  structures
• Comparative biochemistry has identified
  similarities and differences among species
• Taxonomists identify, name, and classify species
• developed by M. Roig