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Evolution
„Nothing in biology makes sense except in the light of evolution”
Theodosius Dobzhansky
Content
1.Creation or evolution?
2.General aspects of evolution
3. Evolution of man
4. Molecular evolution
General aspects of
evolution
0.
Evolutionary thought
1st level: the
fact of evolution
- Is there evolution?
2nd level: basic
evolution is a fact, not only a theory
mechanism of evolution
- Darwinian mechanism or something else?
3rd level: models
of evolution
- mathematical, theoretical
C. Darwin J.B. Lammarc
Darwin’s theory
Species can change, every species stems from another species.
Every living being originates from a common ancestor: LIFE attempted to
come into existence either once or if several times, only one trial was successful Darwin did not know it.
The principle of common descent
Our closest relative is the chimp
Men stem from the animal world
Mechanism of evolution: natural selection
The principle of natural selection was not accepted at Darwin’s time
1.
Darwin’s theory
Charles Darwin:
The origin of species
(1859)
2.
The mechanism of evolution
Individuals within species are variable
VARIABILITY
Variations are passed on to progenies
INHERITANCE
More offspring are produced than can survive
COMPETITION
Survival and reproduction are not random
SELECTION
3.
Natural selection
1. Survival selection
Inanimate environment
– survive environmental challenges
Living environment
2. Reproduction selection
- produce as much progenies as possible
Survival without reproduction is a failure; death after reproduction is not necessary a failure
Natural selection:
- Individuals harboring different alleles exhibit differential survival and reproduction rate
praying mantis
Natural selection
Reproduction strategies:
1. Many offspring, but most of them dies before the reproductive age („r” strategy)
2. Few offspring, but many of them reach the reproductive age („K” strategy)
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The aim
As many progenies as possible should reach the reproductive age in order to
reproduce themselves, and their progenies reproduce themselves, etc. →
Immortality of genetic information
4.
5.
Who cares the offspring?
nobody
Externally fertilized species
male
Principle: if not necessary, do not nurse them; if they have
to be raised, then the other sex should do it
female
Internally fertilized species
together
6.
Darwin’s another theory
- Sexual selection
The most important source of conflict:
- Whose DNA is transmitted to the next generation?
How to decide it?: taste preferences for particular traits or behaviors
Consequence: the specific trait becomes pronounced
- Natural selection adapts individuals to the environment
- Sexual selection: adapts individuals to the demand of other sex
Sexual selection
- Unequal investment
Female chooses
she does not have to be attractive
but the selected male should be the best
The investment of female is higher
Male competes
he is attractive, strong and clever
partner: all the same, just be numerous
7.
Sexual selection
- attractive males
The DOMINANT
see-cow
The SKILLFUL
The HEALTHY
bowerbird
The BEAUTIFUL
1. The Good Genes Theory
2. The Runaway Selection Theory
8.
Types of selection
(summary)
Natural selection
- survival selection
- reproduction selection
Sexual selection
1. Survival selection: survive hostile environment; competition for resources within and between species,
struggle between prey and predators
2. Sexual selection: competition for the sexual partner (s)
3. Reproduction selection: the number and quality of offsprings in a given environmental situation
9.
Why sex is good?
10.
Asexual reproduction is faster ↔ sexual reproduction generates variation
What is variation good for? – it helps for species to survive ever-changing
environment
What is this environment? - parasites within us
For the same reason sugar is sweet to our taste
viruses
pathogenic bacteria
and
fungi
12.
The modern synthesis
Ronald Fisher
J.B.S. Haldane
Sewall Wright
- Population genetics: the 2nd Darwinian revolution
Synthesis of Mendelian genetics and evolution theory
Definition: evolution is the change of gene pool* in time
frequency (%)
100
50
- in the case of a single gene: change of the ratio of alleles in time
gene a and b alleles
1.
10.
20.
30.
40.
50.
60.Time (generations)
* Gene pool: a complete set of alleles in a population at a certain generation
13.
Keyword: fitness
Fitness (W): reproductive success of an allele
W=1-s
1 = optimal fitness
s = selection coefficient
14.
The Selfish Gene Theory
Richard Dawkins
- Genes care only with their own reproductive success, they utilize
the body as a tool to get to next generation
- Genes and not individuals compete with each other
- In a strict sense selfish genes are parasitic sequences in the genome
Replicator (gene)
Vehicle (body)
Sociobiology
W. D. Hamilton
E. O. Wilson
Brother = 1/2 SELF
– altruism toward relatives
Should I whistle or
rather save my life?
Cousin = 1/8 SELF
My genes are also represented in my relatives,
therefore, sometimes it is worth to save them,
even at the expense of my life
Parental love is the result of kin selection
15.
16.
Speciation
Stephen J. Gould
- gradual vs. jumping evolution
Theories for the origin of species:
- Gradualism : speciation occurs by several small steps
- Punctualism: speciation occurs by big jumps
Fossils – lack of transitory forms:
- gradualist answer: we cannot find them
- punctualist answer: there are no such forms
Hopeful monster
Adaptation, complexity
17.
Leigh Van Valen
Adaptation: is the harmony with the environment better and better?
Red Queen* Hypothesis: „running for keeping in the same place” (Van Valen)
Is the more complex more adaptive?: no, we live in a bacterial world
The tree of life
Red Queen: a chess figure in L. Carrol’s
roman: Through the looking-glass
The „purpose” of evolution
We loose all of the materials of our body during or after our life
BODY
CELL
DNA
MOLECULES
Maintenance of the continuity of genetic information,
- maximization of offspring number is only a tool for this
What information do
we transfer and why?
0.1% variation in human population
18.
Evolution of man
and of course of woman
Natural or sexual selection
made us human ?
Natural selection
Source of selection: inanimate or living environment
Result of selection: 1. adaptation of our body and mind to ecological circumstances
2. efficient survival & many offspring
Sexual selection
Source of selection: other sex & competition with the same sex
Result of selection: 1. adaptation of our body and mind to the struggle for the opposite sex
2. many offspring
28.
Footprints of natural
selection
Naked skin
29.
Diving reflex, fat under the skin, attraction to water
Aquatic ape hypothesis
savannah hypothesis
Upright posture
30.
bipedal walk
Function:
penguin-like jumping and swimming
far sight in savannah
throwing
long-distance running
Use of hand
for WORK: natural selection
for ART (?): sexual selection
31.
Giant brain
Mechanism: Neoteny, allometry, heretrochrony
Function: later discussed
Neoteny: juvenile characters are retained in adult age
Allometry: different developmental tempo of various body parts
Heterochrony: certain part of the body start to develop earlier than other ones
32.