1. Evolutionary Biology David Shiuan National Dong Hwa University
Department of Life Science and Institute of Biotechnology
National Dong Hwa University

5. Darwinian Evolution 1809-1882 1809 Lamarck (1744-1829)
Beagle to S. America ( )
1838 Malthus’ “Essay on Population”
1844 “The Origin of Species” ( )
1858 Afred Russel Wallace ( )
“On the tendency of variety to depart indefinitely from the original type” (Linnean Society of London)

7. 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

8. 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

18. Evolution of Evolution Theories
Darwinism
Neo-Darwinian Theory (新達爾文主義)
Snthetic Theory (Julian Huxley:合成說)
Neutral Theory (Motoo Kimura:中立說)
Molecular Evolution

19. 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

20. 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

21. 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)

22. 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

23. 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