Transcript Nothing in biology makes sense except in the light of evolution

CENTER FOR BIOLOGICAL SEQUENCE ANALYSIS
Molecular Evolution
Course #27615
Anders Gorm Pedersen
Molecular Evolution Group
Center for Biological Sequence Analysis
Technical University of Denmark
[email protected]
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
CENTER FOR BIOLOGICAL SEQUENCE ANALYSIS
Classification: Linnaeus
Carl Linnaeus
1707-1778
CENTER FOR BIOLOGICAL SEQUENCE ANALYSIS
Classification: Linnaeus
Hierarchical system
Kingdom
Phylum
Class
Order
Family
Genus
Species
CENTER FOR BIOLOGICAL SEQUENCE ANALYSIS
Classification depicted as a tree
CENTER FOR BIOLOGICAL SEQUENCE ANALYSIS
Classification depicted as a tree
Species Genus Family
Order
Class
CENTER FOR BIOLOGICAL SEQUENCE ANALYSIS
Theory of evolution
Charles Darwin
1809-1882
CENTER FOR BIOLOGICAL SEQUENCE ANALYSIS
Phylogenetic basis of systematics
•
Linnaeus:
Ordering principle is God.
•
Darwin:
Ordering principle is shared descent
from common ancestors.
•
Today, systematics is explicitly based
on phylogeny.
CENTER FOR BIOLOGICAL SEQUENCE ANALYSIS
Darwin’s four postulates
I.
II.
III.
IV.


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”
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