Introduction to Molecular Evolution

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Introduction to Molecular Evolution

• Level 3 Molecular Evolution and Bioinformatics
• Jim Provan

Page and Holmes Chapter 1
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Complete genome sequences
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Complete genome sequences

• DNA sequences are valuable because they provide
  the most detailed anatomy of an organism
• Much of modern biology relies on unravelling
  information stored in gene sequences
• Importance of molecular evolution as a science
• Gene sequences represent an invaluable document
  of the history of life on earth
• How do we recover and interpret this information?

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The tree of life pre 1970s style!
vs.
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The tree of life post 16S rRNA style!
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More recent evolution
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Milestones in the study of molecular evolution

• Early this century, George Nuttal mixed sera and
  antisera from different species to determine
  blood relationships
• Idea was that more closely related species would
  exhibit strongest cross-reactions between sera
  and antisera
• Displayed that degree of similarity between genes
  reflects strength of evolutionary relationship
  between tham
• Despite advances in theoretical evolutionary
  biology (neo-Darwinian synthesis), the study of
  molecular evolution made little progress in the
  next fifty years due to a lack of data

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Milestones in the study of molecular evolution

• In 1953, James Watson and Francis Crick proposed
  the double-helical model of the structure of DNA
• This revealed the mechanism by which DNA carried
  hereditary information between generations

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Milestones in the study of molecular evolution

• In 1955, Fred Sanger and colleagues sequenced the
  first protein, insulin
• Sequences were obtained for cattle, pigs and
  sheep
• Three amino acid differences showed genetic
  variation alongside morphological variation
• Next stage was to build models of molecular
  evolution
• Basic models assumed that evolution was largely a
  stochastic process
• Also realised that with a limited number of bases
  and amino acids, observed change may not
  represent actual change
• Controversial theory that mutations occurred at
  regular intervals the molecular clock

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Milestones in the study of molecular evolution

• Commonly held view on human origins was that
  humans were genetically distinct from great apes

• Work of Sarich Wilson (1967) changed this view
• Cross-reacted serum albumin between primates
• Demonstrated that human, gorilla and chimpazee
  were genetically equidistant and distinct from
  orang-utan
• Calibrated molecular clock

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Milestones in the study of molecular evolution

• Real explosion of information on molecular
  evolution since the advent of PCR
• Nucleotide sequences have replaced protein
  sequences
• Can sequence DNA from samples thousands of years
  old
• Major advances in evolutionary theory

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What this course will cover

• Architecture and organisation of the genome
• Evolution of proteins
• Phylogenetics
• Evolution of natural populations
• Organelle genome evolution
• Bioinformatics
• Tools
• Practical applications