Download Evolutionary biology

Evolutionary Biology
David Shiuan
Department of Life Science and Institute of
Biotechnology
National Dong Hwa University
Darwinian Evolution
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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)
Origin of Species
1859
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Variation is virtually a characteristic of
all/every group of plants and animals
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Every group of organisms overproduces
offsprings
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The most fit will survive
Evolution and Speciation
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Forms of Speciation
1. Anagenesis
species 1  species 2
2. Cladogenesis species 1  species 2 + species 3
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Speciation Definition
Before Darwin – morphologically similar
Modern Concept – can potentially interbreed
Evolution of Evolution Theories
1859
Darwinism
1930-1940
Neo-Darwinian Theory (新達爾文主義)
1942
Snthetic Theory (Julian Huxley:合成說)
1970 -1980 Neutral Theory (Motoo Kimura:中立說)
1980-
Molecular Evolution
Synthetic Theory
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Variation arise by chance and evolution
proceeds through the natural selectionsame as Darwianism
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DNA is known as the genetic material and
undergoes continuous random mutation
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Concept of species – interbreed capability
The Neutral Theory
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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
Punctuated Equilibrium
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Sudden Change vs Gradual Change
Fossil (morphological) evidence – less
than predicted by synthetic theory.
The rate of nucleotide substitution
increase at certain period (fluctuation)
Molecular Clock
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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
Variation
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Among populations in similar
environment – the rate of evolution is
proportional to the genetic variation
within each population
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At the DNA level, organisms may be
heterozygous at almost all gene loci