1. CENTER FOR BIOLOGICAL SEQUENCE ANALYSIS Molecular Evolution Course #27615 Anders Gorm Pedersen Molecular Evolution Group Center for Biological Sequence Analysis Technical University of Denmark gorm@cbs.dtu.dk

2. CENTER FOR BIOLOGICAL SEQUENCE ANALYSIS Theory of evolution as the basis of biological understanding ”Nothing in biology makes sense, except in the light of evolution. Without that light it becomes a pile of sundry facts - some of them interesting or curious but making no meaningful picture as a whole” T. Dobzhansky

3. CENTER FOR BIOLOGICAL SEQUENCE ANALYSIS Classification: Linnaeus Carl Linnaeus 1707-1778

4. CENTER FOR BIOLOGICAL SEQUENCE ANALYSIS Classification: Linnaeus Hierarchical system Kingdom Phylum Class Order Family Genus Species

5. CENTER FOR BIOLOGICAL SEQUENCE ANALYSIS Classification depicted as a tree

6. CENTER FOR BIOLOGICAL SEQUENCE ANALYSIS Classification depicted as a tree SpeciesGenusFamilyOrderClass

7. CENTER FOR BIOLOGICAL SEQUENCE ANALYSIS Theory of evolution Charles Darwin 1809-1882

8. CENTER FOR BIOLOGICAL SEQUENCE ANALYSIS Phylogenetic basis of systematics Linnaeus:Linnaeus: Ordering principle is God. Darwin:Darwin: Ordering principle is shared descent from common ancestors. Today, systematics is explicitly based on phylogeny.Today, systematics is explicitly based on phylogeny.

9. CENTER FOR BIOLOGICAL SEQUENCE ANALYSIS Darwin’s four postulates  Each generation more offspring is born than the environment can support - a fraction of offspring dies without leaving any offspring of its own.  Individuals in a population vary in their characteristics.  Some differences among individuals are based on genetic differences.  Individuals with favorable characteristics have higher rates of survival and reproduction.  Evolution by means of natural selection  Presence of ”design-like” features in organisms: quite often features are there “for a reason”

10. CENTER FOR BIOLOGICAL SEQUENCE ANALYSIS Theory of evolution as the basis of biological understanding “Phylogenies, or evolutionary trees, are the basic structures necessary to think clearly about the differences between species, and to analyze those differences statistically.” Joseph Felsenstein