Transcript Introduction

Nothing in biology makes
sense, except in the light of
evolution
Theodosius Dobzhansky
Lecture outline
1.
2.
3.
4.
5.
Introduction and historical notes
The discovery of the past
The reconstruction of phylogeny
Early times
History of life I: From Proterozoic to Paleozoic
6.
7.
8.
9.
History of life II: From Mesozoic to Cenozoic
Genetic basis of evolutionary change I
Genetic basis of evolutionary change II
Genetic basis of evolutionary change III
10. Genetic variation and fitness
11. Patterns of speciation and extinction
12. Selection, adaptation, and the rise of biological complexity
13. Altruism and sociality
14. Human evolution I
15. Human evolution II
Pre Darwinian Views on Evolution
The classical view
Anaximander of Milet (610-546 BC)
„Anaximander of Miletus considered that from warmed up water and earth emerged either
fish or entirely fishlike animals. Inside these animals, men took form and embryos were held
prisoners until puberty; only then, after these animals burst open, could men and women
come out, now able to feed themselves” (Centorinus, 238 AC)
Empedocles(494?-434? BC)
According to Aristotle Empedocles proposed a struggle for
life in the animal kingdom
Platon (427-347 BC)
developed the essentialism in which the concept of eidos as an ideal
form that is imperfectly imitated by organisms (Timaios).
Variation of organisms is therefore accidental imperfection.
The allegory of
the cave
7 book of Politeia
Aristoteles (384-322 BC)
developed the concept of the scala naturae, the great chain of life.
Starting from inanimate objects and ending by humans and spititual
beings the scala naturae gives every object and organism its
permanent place that is unchangeable.
There are three
main levels:
Minerals
Plants
Animals
From Didacus
Valadus
Rising empiricism
Vesalius (1514-1564)
Founded modern anatomy from dissections of corpses.
He corrected the classical work of Galen who dissected
Barbary apes instead of humans.
He was the first to describe organs in a mechanical way.
William Harvey (1578-1657)
Rediscovered the blood circularly system from dissections
of living animals.
He also proposed that mammals have eggs and he worked
on embryology.
The mechanization of the world
René Descartes (1596-1650)
Descartes was the first to develop a theoretical framework
for the natural sciences.
Descartes suggested that the body works like a machine,
that it has the material properties of extension and motion,
and that it follows the laws of physics.
He paved the way to a mechanistic study of the living
world.
On the other hand he believed that only humans have a
mind and animals lack souls.
Essentialism (eidos)
Importance of
observations
Mechanistic explanation
Carolus Linneus (1707-1778)
His Systema naturae (10. edition 1758) established the framework of
modern classification. While initially believing that species were ‘created’
and fixed, he changed this view in the last edition of the Systema naturae.
Described plant sexuality
Critised Descartes for his mechanistic view of animals
Georges-Louis Leclerc, Comte de Buffon (1707 – 1788)
In his Histoire Naturelle he questioned the biblical view of earth history
and proposed that organism can undergo evolutionary change
although he lacked a precise theory of change.
Immanuel Kant (1724-1804)
The Allgemeine Naturgeschichte und Theorie des Himmels (1755) is
surely the first explicit evolutionary treatment on the basis of Newton’s
mechanic.
He also speculated about the origin of life as a natural process.
Jean Baptiste Lamarck (1744-1829)
As the director of the Muséum National d'Histoire Naturelle he
developed the concept of transmutation while studying molluscs.
Scale of organization
Lamarck developed two ‘laws’ to explain evolution: the law of use and
disuse, and the law of inheritance of acquired characteristics.
Use and disuse: A frequent and continuous use of organs gradually
strengthens, develops and enlarges them. This gives it a power
proportional to the length of time of use.
The permanent disuse of organs imperceptibly weakens and
deteriorates them, and progressively diminishes its functional capacity,
until it finally disappears.
Inheritance of acquired characteristics: All the acquisitions or losses,
through the influence of the environment and through the influence of
the predominant use or permanent disuse of any organ are preserved
through reproduction.
Scala
naturae
Modern biology proved both
‘laws’ to be wrong.
Spontaneous origin of simple
life forms
Time
The rise of Geology
Georges Cuvier (1769-1832)
founded palaeontology and comparative anatomy.
His work on fossil elephants (mammoths) convinced him that
species get extinct.
He explained extinction from the theory of catastrophism.
His discovery of the remains of Pterodactylus and Mosasaurus
convinced him that they were older than 6000 years.
He was sceptical about evolutionary theories.
Charles Lyell (1797-1875)
expounded the principle of uniformitarianism, holding that the same
geological processes operated in the past as in the present:
The present is the key to the past.
He rejected the theory of catastrophism and supported Darwin’s
view on evolution.
Alfred Russel Wallace (1823-1913)
Travelled through the Amazon rainforest and the Malayan
archipelago.
Developed in parallel with Darwin the concept of gradually evolving
species: Every species has come into existence coincident both in
space and time with a pre-existing closely allied species.
In 1958 he and Darwin presented their views on evolution in a joint
meeting of the Linnean Society of London.
Wallacea
Charles Robert Darwin (1809-1882)
The voyage of the Beagle (1831-1836)
Comparative beak sizes of Darwin finches
Darwin’s
Galapagos
tortoise Harriet
(ca 1830-2006)
Population growth and resources
120
100
80
60
40
20
0
The principle of population
Population
Food production
0
2
4
6
Time
Thomas Robert Malthus
(1766-1834)
8
10
Malthus thought that
population growth is a geometric process and
food production a linear.
Today we know that population growth is an
exponential process.
Food availability is more or less constant.
From this conclusion Darwin took his principle of the ‘struggle for existence’:
The number of progenies exceeds the capacity (the amount of resources).
Only some individuals survive.
Surviving probabilities differ due to inherited individual variability.
Darwin’s theory of evolution
Changes of proportions are
caused by differential
survival and reproduction
of individuals due to their
natural variation (natural
selection)
Differentialial survival and reproduction
means that individuals are differentially
adapted to their environment.
The cumulation of different adaptations
causes the split of lineages.
Variation is hereditary
Evolution occurs by change in
the proportion of individuals D
that carry certain characters
E
(population level)
Lineages that do not
reach the top represent
extinct lineages
F
Extinction results from
interspecific competition
Each node represents
a common ancestor of
the lineages above
Character change is a
gradual process
The same evolutionary mechanisms
work at all taxonomic level
A
B
C
Characters of lineages
change over time
(evolution)
All species in a focal evolutionary
tree have a common ancestor
Basic questions of evolutionary research
Does evolution proceed directional
(orthogenesis) or is it a blind process?
Are lineages optimally adapted?
Can adaptations
be acquired?
(mechanistic
basis)
How do
proportions
change?
Do different
evolutionary
processes operate
at different
taxonomic levels?
What is variation?
(material basis)
How common are
speciation and
extinction?
Are nodes always
bifurcations?
How fast do
characters
change? (tempo
of evolution)
Is evolution saltatorial?
Are there ‘hopeful monsters’?
(mode of evolution)
Can we identify common
ancestors?
Are there evolutionary
brushes, networks, or rings ?
The voyage of
the MS Beagle
The origin of
species
toms
Domestication
of plants and
animals
Vegetable
mould
and
Earth-worms
General literature
Darwin Ch. 1859. The origin of species by means of natural selection, or the
preservation of favored races in the struggle for life. http://www.humannature.com/darwin/origin/contents.htm
The voyage of the Beagle. http://home.att.net/~p.caimi/darwin.html
Platon. Timaios. http://en.wikipedia.org/wiki/Timaeus_%28dialogue%29
Aristoteles. De Anima. http://ccat.sas.upenn.edu/jod/texts/aristotle.soul.html
Immanuel Kant. Allgemeine Naturgeschichte und Theorie des Himmels.
http://www.mala.bc.ca/~johnstoi/kant/kant2e.htm
Today’s literature
Evolution. Selected papers and commentary.
http://post.queensu.ca/~forsdyke/evolutio.htm
A concise history of evolutionary theories since Darwin. http://www.unikassel.de/fb19/plantphysiology/niklas.pdf
History of Science. http://biology.clc.uc.edu/courses/bio104/hist_sci.htm
Some biographies. http://www.ucmp.berkeley.edu/help/topic/history.html