Download Lecture 0.1: History and Introduction

Evolutionary Genetics: Part 0.1
General Introduction
S. chilense
S. peruvianum
Winter Semester 2012-2013
Prof Aurélien Tellier
FG Populationsgenetik
Evolutionary biology: study of the evolution of life
Apparition of life around 4.6
billions years ago
Since: history of evolution by
adaptations and extinctions
The history of life evolution is not
over!!!
Evolutionary theory explains the transformation of life forms!
History of the Evolution idea
Paradigm shifts in Science
Thomas Kuhn
A bit of history: the foundations
Bases of species descriptions by naturalists:
Carl von Linné
Comte de Buffon
Alexander von Humboldt
Lamarck: first „Evolutionary theory“ (1809)
Each organism has the ability to adapt to his environment
Each organism tends to reach for perfection.
Abilities aquired during the life time will be transmitted to the next
generation
Darwin and Wallace: Theory of selection and common descent (1838)
Species are developing continuously and die eventually out
Similar organisms descent from a common ancestor
Evolution occurs at slow pace, not by jumps
Evolution proceeds by means of natural selection
A bit of history: the foundations
Fossil records
A bit of history: the foundations
Biogeography
A bit of history: the foundations
Comparative anatomy
A bit of history: the foundations
Molecular biology
A bit of history: the foundations
Darwin‘s four postulates
Individuals within a species are variable
A part of this natural variation will be transmitted to the next generation
The amount of offspring of individuals is (much) higher than the capacity
of the environment, thus there is concurrence (Malthusian idea)
At each generation the most succesful individuals reproduce and transmit
their characteristics further, the unsuccesful ones do not
=> The survival and reproduction is not random, but driven by natural
selection
Example: Galapagos/Darwin-Finches
(see Peter and Rosemary Grant works)
A bit of history: the foundations
Some important definitions in a Darwinian world:
Darwinian Evolution: continuous changes observed in populations with time
Darwinian Fitness: ability of an individual to survive and to reproduce in a given
environment
Adaptation: characteristics of an organism which increases its fitness in
comparison to other individuals which do not carry this advantageous trait
Homology: similarity due to common ancestry
Analogy: similarity in function but without common ancestry
A bit of history: the foundations
Some important definitions in a Darwinian world:
Rudimentary Organs: organs without apparent function which are homogues to
functionnal organs in closely related species
Convergent Evolution: independent evolution of analogue similarities between
species as adaptation to similar environmental conditions
Exaptation: shift of function of a trait during evolution
Solanaceae clade, Asterid genus
Cucurbitale clade, Malvaceae genus
A bit of history: the foundations
Evolutionary Theory 1.0: Darwinism
Common descent
Natural selection
Missing a theory of heredity
(after having flirted with Lamarckism and blending inheritance)
A bit of history: the foundations
Evolutionary Theory 1.1: neo-Darwinism
Rejection of Lamarckism
Separation of soma and germ lines
August Weissman
Alfred R. Wallace
Still missing a theory of heredity…
A bit of history: the modern synthesis
Evolutionary Theory 2.0:
birth of the modern synthesis
Compatibility between Mendelism and statistical genetics
Theory of selection and random drift
=> Birth of population genetics
R.A. Fisher
Sewall Wright
J.B.S Haldane
A bit of history: the modern synthesis
Evolutionary Theory 2.1: the mature modern synthesis
Variation in natural populations
Species concept, speciation process
Compatibility of gradualism with paleontology
Applicability of Darwinism to variety of genetic systems in plants
T. Dobzhansky
J. Huxley
G.L. Stebbins
E. Mayr
G.G. Simpson
isolating mechanisms
cline
Plant evolution
speciation
paleogeography
A bit of history: the modern synthesis
Evolutionary Theory 2.1: the mature modern synthesis
„neutral theory of evolution“
Kin selection
Evolution and game theory
Currently involves:
B. Charlesworth
N. Barton
B. Clarke
A. Orr
M. Kimura
W.D. Hamilton
J. Maynard-Smith
…
A bit of history: the modern synthesis
“The major tenets of the evolutionary synthesis were that
-
populations contain genetic variation that arises by random mutation and
recombination;
-
populations evolve by changes in gene frequency brought about by random genetic
drift, gene flow, and especially natural selection;
-
most adaptive genetic variants have individually slight phenotypic effects so that phenotypic
changes are gradual;
-
diversification comes about by speciation, which normally entails the gradual evolution of
reproductive isolation among populations;
-
and these processes, continued for sufficiently long, give rise to changes of such great
magnitude as to warrant the designation of higher taxonomic levels.”
Douglas Futuyma
A bit of history: the modern synthesis
No theory is perfect, requires constant questioning,
further refinements….
Following new discovery in genetics, molecular
biology, ecology, sociobiology, …
From Massimo Pigliucci
Pigliucci and Müller
“Evolution – The extended synthesis”
MIT press 2010
A bit of history: new questions
A bit of history: new questions
A bit of history: arising questions
Andreas
Wagner
A bit of history: arising questions
A bit of history: arising questions
A bit of history: arising questions
A bit of history: arising questions
Pigliucci
A bit of history: arising questions
A bit of history: current summary of the field
These are exciting times: knowledge on genomes and combination of
molecular/epigenetic/ecological studies becomes possible
My research: new questions