Evolution

Theodosius Dobzhansky

„Nothing in biology makes sense except in the light of evolution”

1.Creation or evolution?

2.General aspects of evolution

3. Evolution of man

4. Molecular evolution

Content

General aspects of

evolution

1st level: the fact of evolution

2nd level: basic mechanism of evolution

3rd level: models of evolution

- Darwinian mechanism or something else?

- mathematical, theoretical

C. Darwin J.B. Lammarc

Evolutionary thought

- Is there evolution? evolution is a fact, not only a theory

0.

The principle of common descent

Men stem from the animal world

Mechanism of evolution: natural selection

1.

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 natural selection was not accepted at Darwin’s time

Our closest relative is the chimp

Darwin’s theory

Charles Darwin:

The origin of species

(1859)

The mechanism of evolution

Darwin’s theory

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

2.

Survival without reproduction is a failure; death after reproduction is not necessary a failure

Natural selection

Inanimate environment Living environment

Natural selection: - Individuals harboring different alleles exhibit differential survival and reproduction rate

1. Survival selection – survive environmental challenges

2. Reproduction selection - produce as much progenies as possible

3.

praying mantis

Natural selection

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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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

Reproduction strategies:

The aim

4.

Externally fertilized species

Internally fertilized species

nobody

male

female

together

5.

Who cares the offspring?

Principle: if not necessary, do not nurse them; if they have

to be raised, then the other sex should do it

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

6.

Sexual selection - Unequal investment

The investment of female is higher

Male competes he is attractive, strong and clever

partner: all the same, just be numerous

Female chooses she does not have to be attractive

but the selected male should be the best

7.

Sexual selection - attractive males

1. The Good Genes Theory

The DOMINANT The HEALTHY The SKILLFUL

The BEAUTIFUL

2. The Runaway Selection Theory

8.

bowerbird see-cow

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?

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

10.

viruses pathogenic bacteria and fungi

Synthesis of Mendelian genetics and evolution theory

Definition: evolution is the change of gene pool* in time - in the case of a single gene: change of the ratio of alleles in time

The modern synthesis

- Population genetics: the 2nd Darwinian revolution

* Gene pool: a complete set of alleles in a population at a certain generation

Ronald Fisher J.B.S. Haldane Sewall Wright

Time (generations)

f

req

uen

cy (

%)

50

10

0

1. 10. 20. 30. 40. 50. 60.

gene a and b alleles

12.

Keyword: fitness

Fitness (W): reproductive success of an allele

W = 1 - s

1 = optimal fitness

s = selection coefficient

13.

The Selfish Gene Theory

- 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

14.

Replicator (gene) Vehicle (body)

Richard Dawkins

Brother = 1/2 SELF

Cousin = 1/8 SELF

15.

Should I whistle or

rather save my life?

W. D. Hamilton E. O. Wilson

My genes are also represented in my relatives,

therefore, sometimes it is worth to save them,

even at the expense of my life

Sociobiology – altruism toward relatives

Parental love is the result of kin selection

Speciation - gradual vs. jumping evolution

Fossils – lack of transitory forms:

- gradualist answer: we cannot find them

- punctualist answer: there are no such forms

Stephen J. Gould

Theories for the origin of species:

- Gradualism : speciation occurs by several small steps

- Punctualism: speciation occurs by big jumps

16.

Hopeful monster

Adaptation, complexity

Red Queen: a chess figure in L. Carrol’s

roman: Through the looking-glass

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

17.

The tree of life

We loose all of the materials of our body during or after our life

Maintenance of the continuity of genetic information, - maximization of offspring number is only a tool for this

What information do

we transfer and why?

The „purpose” of evolution 18.

BODY CELL DNA MOLECULES

0.1% variation in human population

Evolution of man and of course of woman

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

Natural or sexual selection

made us human ?

28.

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

Sexual selection

Natural selection

selection Footprints of natural

Naked skin 29.

Aquatic ape hypothesis savannah hypothesis

Diving reflex, fat under the skin, attraction to water

30.

Upright posture bipedal walk

penguin-like jumping and swimming

far sight in savannah throwing long-distance running

Function:

Use of hand 31.

for WORK: natural selection

for ART (?): sexual selection

Giant brain 32.

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