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EVOLUTION

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Fossil evidence for transitional forms like Archaeopteryx is strong. ... Archaeopteryx was the first bird according to the fossil record. ... – PowerPoint PPT presentation

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Title: EVOLUTION


1
EVOLUTION
  • Nancy G. Morris
  • Volunteer State Community College

2
Theory of Evolution
  • The theory of evolution states that
  • life arose from random non-living chemical
    processes that took place in the ancient oceans.
  • mutations and natural selection have brought
    great change in organisms.
  • Life has become more diverse and complex.

3
THE ORIGIN OF LIFE
  • Life on earth originated
  • approximately 3.5 billion years ago.

4
THE ORIGIN OF LIFE
  • The theory states that abiotic chemical processes
    occurring on the early earth produced basic
    precursors leading to the building blocks of
    life.
  • In 1953, Miller and Urey achieved synthesis of
    small organic molecules from abiotic compounds
    like those thought to exist on the early earth.

5
THE ORIGIN OF LIFE
  • They produced amino acids and other building
    blocks by electrically sparking atmospheric gases
    that probably existed on the early earth.

6
Comparative Anatomy
  • The bone types in the limbs of amphibians,
    reptiles, birds, and mammals is very similar.
  • This suggests common ancestry.

7
THE ORIGIN OF LIFE
  • An organic soup -- a mixture of all sorts of
    carbohydrate, amino acids, nucleotide, and lipid
    molecules --accumulated in the early oceans as
    atmospheric gases reacted.
  • Energy was supplied by lightning and UV
    radiation from the sun.

8
THE ORIGIN OF LIFE
  • Laboratory simulations of early earth conditions
    have produced organic polymers such as
    polypeptides.
  • Amino acids form polypeptides abiotically when
    water with amino acids drys on hot clay.

9
THE ORIGIN OF LIFE
  • Heterotrophic protocells probably came next.
  • It is thought that these protocells had a cell
    membrane.

10
THE ORIGIN OF LIFE
  • Protocells must have fed on the organic soup of
    the early oceans.
  • Since there was no oxygen, we assume that the
    first cells were anaerobic fermenters.

11
THE ORIGIN OF LIFE
  • Once the protocell was capable of reproduction,
    it became a true cell, and biological evolution
    began.
  • Many scientists think that these ancient cells
    had RNA for their genetic code and later cells
    had DNA.

12
Classification 3 Domains
  • Bacteria Archaea Eukaryotes
  • Anaerobic Heterotrophs
  • capable of division
  • Anaerobic Heterotrophic Protocells
  • Organic Soup

13
Current Classification Schemes
14
HISTORY OF THE EVOLUTION CONCEPT
  • The concept of evolution was formulated by Greek
    philosophers over 2000 years age.
  • LeMarck (a French biologist early 1800s)
    proposed a theory of evolution based on acquired
    characteristics.
  • Charles Darwin (1860s) published his theory of
    evolution based on natural selection.

15
Mechanisms of Evolution
  • Natural selection
  • Mutation
  • Isolation of Populations
  • Mass Extinctions

16
Natural Selection
  • Darwin and Wallaces Theory
  • Natural Selection means Survival of the best
    adapted.
  • Nature is prolific. More individuals are produced
    than the environment can support -- thus
    competition.
  • Individuals with mutations which are beneficial
    (cause better adaptation to the environment)
    have a better chance of surviving.

17
ISOLATION OF POPULATIONS
  • Darwins observations occurred on the Galapagos
    Islands
  • When a small population becomes geographically
    isolated from the main population, the small
    population tends to evolve into a separate
    species (speciation) because gene flow has been
    cut off from the main population.

18
Continental Drift
19
MASS EXTINCTIONS
  • The fossil record shows that speciation
    (evolution) is most rapid following a mass
    extinction.
  • Mammals and birds evolved rapidly into many
    different species after the dinosaurs were wiped
    out 65 million years ago.
  • Humankind might not be here today had the
    dinosaurs not become extinct.

20
THE PACE OF EVOLUTION
  • Darwin thought evolution proceeded gradually.
  • Stephen Gould and some other modern
    paleontologists think that evolution tends to
    occur in spurts -- especially after a mass
    extinction.
  • Gould believes that evolution is often rapid,
    then a new species remains constant for long
    periods until the next major environmental change
    spurs another burst of evolution.

21
THE PACE OF EVOLUTION
  • Biologists know of some species that have changed
    very little over many millions of years because
    they are so well adapted to their niche or their
    way of life.

22
Evolutionary Evidences
  • Artificial selection
  • Fossil record
  • Comparative anatomy
  • Comparative embryology
  • Comparison of DNA
  • Vestigial structures

23
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24
Artificial Selection
  • All breeds of dog have evolved from a wolf
    ancestor through artificial selection by
    humankind over the last 10,000 years.
  • Cabbage, broccoli, cauliflower, brussel sprouts
    all have been derived from a common ancestor by
    humankind in just a few thousand years.

25
FOSSIL RECORD
  • Fossils of the simplest organisms are the oldest.
  • Fossil evidence for the evolution of vertebrates
    is more complete than for soft-bodied animals.
  • Fossil evidence for transitional forms like
    Archaeopteryx is strong.
  • Fossil evidence for human evolution is compelling.

26
Comparative Anatomy
  • The bone types in the limbs of amphibians,
    reptiles, birds, and mammals is very similar.
  • This suggests common ancestry.

27
COMPARATIVE EMBRYOLOGY
  • All vertebrate animals are similar in their
    early embryonic development.
  • They all have a notochord, tail, and gill pouches
    in their early development.
  • In humans, the notochord is replaced by backbone,
    the tail degenerates, and gill pouches become the
    Eustachian tube, tonsils, and glands in the
    neck region.

28
COMPARISON OF DNA
  • Chimpanzees and humans have a DNA similarity of
    99.
  • Humans and cows would have less DNA similarity.
  • Humans and jellyfish would have still fewer genes
    in common.
  • The degree of DNA similarity between two
    organisms indicates how closely related they are.

29
VESTIGAL STRUCTURES
  • The appendix, coccyx, and embryonic tail are
    vestigal structures in humans.
  • Nonfunctional eyes in cave fish are vestigal.
  • Vestigial pelvic bones are present in the body of
    the python.

30
VERTEBRATE EVOLUTION
  • The ancestor of the vertebrates was a small
    fishlike animal with a notochord that lived in
    the seas about 500 million years ago.
  • The first fishes were jawless. Today the only
    surviving jawless fishes are lamprey.

31
VERTEBRATE EVOLUTION
  • Some of the jawless fishes evolved into jawed
    fishes .
  • The early jawed fishes evolved into
  • cartilaginous fishes
  • bony fishes

32
VERTEBRATE EVOLUTION
  • Today there are many bony fishes.
  • Cartilaginous fishes include sharks, skates, and
    rays.
  • Some of the early lobe-finned fishes evolved into
    the first amphibians.

33
VERTEBRATE EVOLUTION
  • Amphibians today include frogs, toads, and
    salamanders.
  • Some of the early amphibians evolved into the
    first reptiles.
  • Today reptiles include snakes, lizards,
    turtles, crocodiles, and alligators.

34
VERTEBRATE EVOLUTION
  • The reptiles are better adapted to dry land
    living because of their waste-proof eggs and
    scaly skin.
  • Some of the early reptiles evolved into the first
    birds and mammals.

35
VERTEBRATE EVOLUTION
  • Archaeopteryx was the first bird according to the
    fossil record.
  • It had these reptilian features
  • teeth in beak
  • claws
  • long reptilian tail vertebrae

36
VERTEBRATE EVOLUTION
  • Archaeopteryx was a bird because it had feathers.
  • Early mammals were shrew-like animals.
  • When dinosaurs became extinct, birds and mammals
    expanded into many diverse species.

37
HOMINID EVOLUTION
  • Hominids are primates which walk upright.
  • The first hominid we have fossils of is Lucy
    Australopithecus afarensis from Africa.

38
Hominid Evolution
  • Homo habilis used stone tools.
  • Homo erecutus used fire.
  • Homo sapiens neanderthalensis lived during the
    Ice Age. They were hardy, muscular hunters who
    buried their dead.

39
Major episodes
40
Earths Inhabitants
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