Basics of evolution

1. Evolution I & II

2. Evolution I
 Several types of evolution:
A. Cosmic --- the stars, planets, universe
B. Chemical --- development of life
C. Organic --- biological
D. Cultural --- social / societies
 We'll be dealing with organic evolution

3. Evolution I
 Evolution is the gradual
development of life .
 It is the descent of
organisms with
modification (Darwinian).
 Put simply: Evolution is
change over time .
 Fitness is the ability to live
to reproduce .

4. Evolution I
 Adaptation is any trait that is determined genetically
and enhances an organism's fitness.
 Adaptation
a. behavioral changes (adaptations)
b. morphological changes (adaptations)
c. physiological changes (adaptations)
 Evolution is a slow and gradual process. Shorter
the generation time, faster evolution occurs.
 Micro evolution special kind occuring in few
generations (2-3 hours in some bacteria) in a given
population.

5. Evolution I
 Evolution is:

a. Opportunistic --- new adaptation do
not arise out of thin air, they arise from
something already present -- mutations

b. Undirected changes --- cannot tell
what will happen next -- random

6. Evolution I
 Rapid change in terms
of evolution is 10,000
years.
 This equals 1/2 mm of
in a rock layer, brief to
a geologist.

7. Evolution I
 James Hutton in 1795 rejected
previous ideas and state the present
is the key to the past.
 He looked at sediments and
determined it would take a vast
amount of time to accumulate.
 He advance the idea that the earth
was millions of years old.
 Charles Lyell made Hutton's work
popular and wrote book that looked
at slow gradual changes, fossil
records and that new species and
extinction were slow processes.

8. Evolution I
 Charles Lyell made
Hutton's work
popular and wrote
book that looked at
slow gradual changes,
fossil records and that
new species and
extinction were slow
processes.

9. Evolution I
 Fossils form when organisms
are covered with sediments.
 They are found in sedimentary
rocks. These rocks are made
when rock and soil particles are
cemented by water and under
pressure
 Because most organisms
decompose, there are few
fossils found of soft tissue
organisms.
 Most fossils are made out of
shells & bone

10. Evolution I
 Age of fossils are
determined by:
a) Radioactive isotopes or
b) Carbon14 dating requires
presence of carbon
 both use half-life to
determine age of object.

11. Evolution I

12. Evolution I
 Carbon 14 isotope has half-life of 5,
730 years.
 In 5,730 years there will be half the
energy left in the original C14
sample.
 14
CO2 is found in all living
organisms.
 This method only works on items
less than 20,000 years old.
 Other isotopes are used to test
surrounding rocks for dating older
specimens.

13. Evolution II
 Geologic time is divided into:
 Eras (4),
 Periods (11),
 Epochs (7 all during the Cenozoic
era)

14. Evolution II
 When organisms are found in the fossil record
and are no longer living then they are said to be
extinct.
 By studying the fossil record different
organisms can be compared.

15. Evolution II
 Scientists look at homologous body structures.
 Example:
n whale: flipper
n lion: forearm
n human: arm
n bird: wing
n fish: fin

16. Evolution II
 Some structures have no
apparent use, these are
called vestiges or vestigial
organs. It is thought these
structures were used by the
organism's ancestors.

17. Evolution II
 Besides comparing homologous
structures, scientists also look at
1. embryology
2. biochemistry
a) genetic code
b) codons some
c) protein syn. pathway
d) DNA RMA & amino acids
e) others

18. Evolution II
 Old Theories
 Before Lamark and then Darwin, several
theories existed. Their common factor
was changes occurred on a fixed scale
or time line.

19. Evolution II
Lamark (French)
 Believed organisms changed in response to
environment.
 First to turn the fixed scale into a moving scale of
progress, stating new species were continually
being created.
 At the lower end of the scale by spontaneous
generation.

20. Evolution II
 Lamark
 His ideas appeared in his book Philosphie
Zoologique (1809) . He was first to place
scale from lower life forms to man. On
problem is he ignored gaps in the scale.
The theories arising from Lamark are:
1. of need
2. of use and disuse
3. Acquired characteristics (example: giraffes'
necks).
4. acquired traits can be passed to offspring directly

21. Charles Darwin
 Darwin was born in Shrewsbury, England, 160 miles
northwest of London on the 12th of February 1809,
the same day that Abraham Lincoln (16th President of
the USA) was born in Kentucky, USA. Lincoln died
in 1865 and Darwin in 1882. On the 12th of February
1882, Darwin wrote to a friend that "my course is
nearly run" and within two months, on 19 April 1882,
he had a fatal heart attack and died. His remains were
conveyed by a funeral cortege on April 26 and he was
interred in Westminster Abbey, London. In 1876, at
the age of sixty-eight, Darwin wrote in his
Autobiography that the five-year voyage on His
Majesty's Ship Beagle, over the years of 1831-1836
was "by far the most important event of my life and
has determined my whole career" and the scientific
world should be grateful for that.

22. Charles Darwin
 Charles Darwin was greatly influenced by
the geologist Adam Sedgwick and
naturalist John Henslow in his development
of the theory of natural selection, which
was to become the foundation concept
supporting the theory of evolution.
Darwin’s theory holds that environmental
effects lead to varying degrees of
reproductive success in individuals and
groups of organisms. Natural selection
tends to promote adaptation in organisms
when necessary for survival. This
revolutionary theory was published in 1859
in Darwin’s now famous treatise On the
Origin of Species by Means of Natural
Selection.

23. Evolution II
 Charles Darwin
 Wrote Origin of the Species, which sold out in
the first day and a total of six editions were sold
during his life.
 The following ideas were expressed in his book:
1. evolution has occurred
2. mechanism of evolution is natural selection
 Evolution is a process.
 Natural selection is the mechanism by which
evolution takes place (occurs).

24. Evolution II
Six steps to Darwin's theory of natural selection:
1. All organisms produce more offspring than can
actually survive.
2. Every organism faces a constant struggle to
survive.
3. The individuals of a given species vary
4. The individuals that are best adapted to the
environment survive.
5. The organisms that survive pass their traits on to
offspring.
6. The population will become better fit for the
environment.

25. Darwin’s voyage on the HMS
Beagle
Voyage of the Beagle. From de Beer (1964, p. 39).

26. Darwin’ Beagle Voyage
 "As far as I can judge of
myself I worked to the
utmost during the voyage
from the mere pleasure of
investigation, and from
my strong desire to add a
few facts to the great mass
of facts in natural
science."
 — Charles Darwin

27. Darwin’ Beagle Voyage
 Galapagos Islands
off the coast of
Ecuador

28. Darwin’s Finches
 Darwin's finches. The finches numbered 1-7 are
ground finches. They seek their food on the ground or
in low shrubs. Those numbered 8-13 are tree finches.
They live primarily on insects.
 1. Large cactus finch (Geospiza conirostris)
 2. Large ground finch (G. magnirostris)
 3. Medium ground finch (Geospiza fortis)
 4. Cactus finch (G. scandens)
 5. Sharp-beaked ground finch (G. difficilis)
 6. Small ground finch (G. fuliginosa)
 7. Woodpecker finch (Cactospiza pallida)
 8. Vegetarian tree finch (Platyspiza crassirostris)
 9. Medium tree finch (Camarhynchus pauper)
 10. Large tree finch (Camarhynchus psittacula)
 11. Small tree finch (C. parvulus)
 12. Warbler finch (Certhidia olivacea)
 13. Mangrove finch (Cactospiza heliobates)

29. Darwin’s Finches

30. The End