Download A bit of history: the modern synthesis

Application Evolution: Part 0.1
General Introduction
S. chilense
S. peruvianum
Summer Semester 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
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
Evolutionary Theory 1.0: Darwinism
Common descent
Natural selection
Connection agriculture (human selection) and Natural selection
Missing a theory of heredity
Agriculture = accelerated and directed evolution?
Diamond and Bellwood, Science, 2003
Darwin and disease
Darwin, C. R. to Gray, Asa, 16 Apr [1866]
My dear Gray
I have been a scandalously ungrateful, & idle dog for not having thanked you
very long ago for the second article on climbing plants, which pleased me greatly.
But, as I have before said, now that I work a little, I seldom feel inclined to write
to anyone, but this evening the spirit has moved me to do so, though I have little
to say, & my dear amanuensis is poorly with influenza, which has likewise
knocked me up for a week.—
….
Note: According to Emma Darwin's diary (DAR 242), she came down with
influenza on 9 April. CD had contracted influenza the previous day, having gone
to bed with a cold on 6 April. By 14 April, CD had recovered.
From Darwin Correspondence Database
No mention that parasites might be life forms and evolve….
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
The „Holy Trinity“ of evolutionary biology
R.A. Fisher
Sewall Wright
J.B.S Haldane
A bit of history: the modern synthesis
Evolutionary Theory 2.0:
birth of the modern synthesis
Statistical population genetics: Wright-Fisher model
Model of evolution: geometric model of Fisher
Fisher‘s fundamental theorem of selection
R.A. Fisher
A bit of history: the modern synthesis
Evolutionary Theory 2.0:
birth of the modern synthesis
Statistical population genetics: Wright-Fisher model
Fitness landscape: how populations adapt?
Sewall Wright
A bit of history: the modern synthesis
Evolutionary Theory 2.0:
birth of the modern synthesis
Statistical population genetics
Quantitative genetics
First one to point out the role of parasites and
coevolution
The Causes of Evolution (Haldane 1932)
J.B.S Haldane
“A study of the causes of death in man, animals, and plants leaves
no doubt that one of the principal characters possessing survival
value is immunity to disease. Unfortunately, this is not a very
permanent acquisition, because the agents of disease also evolve,
and on the whole more rapidly than their victims.”
A bit of history: the modern synthesis
Evolutionary Theory 2.0:
birth of the modern synthesis
Disease and Evolution*
J. B. S. Haldane
J.B.S Haldane
SUMMARY
Examples quoted by biologists, in order to show hownatural
selection is working, almost present structures or functions concerned either with protection against natural forces or against
predators, or with purchase of food or mates. The Author
suggests that the struggle against diseases, and especially
infectious diseases, has been a very important evolutionary agent
and that some of its results have been rather unlike those of the
struggle for life in its common meaning
Haldane, J. B. S. 1949 Disease and evolution. La Ricerca
Scientifica 19, 68–76
A bit of history: the modern synthesis
I want to suggest that the struggle against disease, and particularly infectious disease, has been a very important
evolutionary agent,…
J.B.S Haldane
Under the heading infectious disease I shall include, when
considering animals, all attacks by smaller organisms, including
bacteria,viruses, fungi, protozoa, and metazoan parasites. In the
case of plants it is not so clear whether we should regard aphids
or caterpillars as a disease….
Within a species of plant we can generally find individuals resistant to any particular race of rust (Uredineae) or any particular
bacterial disease. Quite often this resistance is determined by a
single pair, or a very few pairs, of genes….
A bit of history: the modern synthesis
J.B.S Haldane
Probably a very small biochemical change will give a host species a
substantial degree of resistance to a highly adapted microorganism.
This has an important evolutionary effect. It means that it is an
advantage to the individual to possess a rare biochemical phenotype.
For just because of its rarity it will be resistant to diseases which
attack the majority of its fellows. And it means that it is an advantage
to a species to be biochemically diverse, and even to be mutable as
regards genes concerned in disease resistance. For the biochemically
diverse species will contain at least some members capable of
resisting any particular pestiience. And the biochemically mutable
species will not remain in a condition where it is resistant to all the
diseases so far encountered, but an easy prey to the next one.
A beautiful example of the danger of homogeneity is the case of the
cuitivated banana clone « Gross Michel » which is well adapted for
export and has been widely planted in the West Indies. However it is
susceptible to a root infection by the fungus Fusarium cubense
to which many varieties are immune, and its exclusive cultivation in
many areas has therefore had serious economic effects.
A bit of history: the modern synthesis
Evolutionary Theory 2.1: the mature modern synthesis
„neutral theory of evolution“ (Kimura)
Kin selection (Hamilton)
Evolution and game theory (Maynard-Smith)
Red Queen hypothesis (van Valen)
M. Kimura
W.D. Hamilton
J. Maynard-Smith
L. Van Valen
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
Population genetics
Evolution = changes between generations of frequency of
characters, traits or alleles
Why study the genetics of populations?
the population is the main unit at which selection acts !!!!!!!!!
Population genetics
Populations and species show variability:
what type and how much genetic variation exist within
populations/species?
what are the forces that influence the amount of variation
within populations?
Population genetics: 4 evolutionary forces
random genomic processes
(mutation, duplication, recombination, gene conversion)
molecular diversity
natural
selection
random spatial
process (migration)
random demographic
process (drift)
Population genetics investigates the laws governing the genetic structure of
populations, and changes in allele frequencies over time
Population genetics: 4 evolutionary forces
random genomic processes
(mutation, duplication, recombination, gene conversion)
molecular diversity
natural
selection
random spatial
process (migration)
phenotypic
variability
random demographic
process (drift)
Color code
Color code:
Red = Important result or definition
Purple: exercise to do
Green: some bits of maths