Evolutionary Biology

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Evolutionary Biology

• David Shiuan
• Department of Life Science and Institute of
  Biotechnology
• National Dong Hwa University

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Darwinian Evolution 1809-1882

• 1809 Lamarck (1744-1829)
• Beagle to S. America (1831-1836)
• 1838 Malthus Essay on Population
• 1844 The Origin of Species (1844-1859)
• 1858 Afred Russel Wallace (1823-1913)
• On the tendency of variety to depart
  indefinitely from the original type (Linnean
  Society of London)

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Origin of Species 1859

• Variation is virtually a characteristic of
  all/every group of plants and animals
• Every group of organisms overproduces offsprings
• The most fit will survive

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Evolution and Speciation

• Forms of Speciation
• 1. Anagenesis species 1 ? species 2
• 2. Cladogenesis species 1 ? species 2
  species 3
• Speciation Definition
• Before Darwin morphologically similar
• Modern Concept can potentially interbreed

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Evolution of Evolution Theories

• 1859 Darwinism
• 1930-1940 Neo-Darwinian Theory (??????)
• 1942 Snthetic Theory (Julian
  Huxley???)
• 1970 -1980 Neutral Theory (Motoo Kimura???)
• 1980- Molecular Evolution

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Synthetic Theory

• Variation arise by chance and evolution proceeds
  through the natural selection- same as Darwianism
• DNA is known as the genetic material and
  undergoes continuous random mutation
• Concept of species interbreed capability

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The Neutral Theory

• Motoo Kimura (National Institute of Genetics
  Japan)
• Genetic difference ? natural selection
• ? the more adaptive one should spread ? the
  observed degree of variation should be low
• Most difference among alleles are adaptively
  neutral and accumulated the reality

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Punctuated Equilibrium

• Sudden Change vs Gradual Change
• Fossil (morphological) evidence less than
  predicted by synthetic theory.
• The rate of nucleotide substitution increase at
  certain period (fluctuation)

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Molecular Clock

• A given gene or protein as a molecular clock
  the basic concept of molecular evolution
• Assumptions the mutation rate is constant among
  species and at all times

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Variation

• Among populations in similar environment the
  rate of evolution is proportional to the genetic
  variation within each population
• At the DNA level, organisms may be heterozygous
  at almost all gene loci