1. Descent with Modification: A Darwinian View of Life
Click on Picture

2. Evolutionary history

3. Historic Context
Plato and Aristotle believed that organisms were perfectly formed and adapted to the world
Judeo Christian theology believed:
that the world is 6,000 years old
species were created individually
Natural Theologians searched for God’s plan through the study of nature

4. Carolus Linnaeus founder of taxonomy and binomial nomenclature
Clustered similar organisms into categories, he did not assume any evolutionary relationship based on this classification scheme

5. Principles of Populations
Thomas Malthus (1798) published that populations increase faster than environment can handle
Capacity to over-reproduce is seen in all species
Eventually populations stop increasing in size and reach a steady state (carrying capacity)

6. Geology
Hutton ( 1795) theory of gradualism that major changes are the result of slow small changes
Lyell (1830) geological changes throughout time have been subjected to the same forces
Conclusions:
If geological changes are slow earth is older than 6,000 years old
the slow changes can build and result in profound environmental changes over time

7. Sir Charles Lyell (1797 – 1875) Born in Scottland
Attended Oxford University
-> mathematics and geology
Knighted for
scientific accomplishment
Principles of Geology (12 editions).
action of the rain, sea, volcanoes and earthquakes
explained the geological history of more ancient times.

8. Relating geological evolution to biological evolution:
Theories of biological evolution begin in the late eighteenth century
Lamarck was the first to propose a mechanism that related environment to biological changes (1809)
Use and Disuse
Inheritance of Acquired Characteristics

9. Jean-Baptist Lamarck (1744 -1829)
-> French zoologist
-> ignored or attacked
during his lifetime
-> Lamarck proposed a different mechanism for evolution than Darwin, but the predicted result is the same

10. Jean-Baptist Lamarck First Law
-> change in the environment changes the needs
of animals
-> causes a change in their behavior
-> altered behavior leads to greater or lesser use of
structures or organs
-> structures increase/decrease in size over
generations
Second Law
-> such changes are inheritable

11. Georges Cuvier (1769 – 1832)
French anatomist and father of paleontology
History of life is recorded in geological strata
containing fossils
He noticed that species appear and disappear in the fossil record
He did not use this to support evolution, but developed catastrophism
Fossils
-> essential for understanding evolutionary
relationships
-> connection between past and present

12. Riddles…
=> Some fossils do not resemble existing species!
=> Some seashells can be found on mountaintops

13. Stratification
Placing fossils in a historical sequence
Deeper strata are older

14. Scientists influencing Darwin

15. Darwin Sails on Beagle at 22
Noted that flora and fauna of islands off of SA were more like continental species than those of other islands with similar climate and habitats
Contributions of Lyell and Malthus along with his observations lead him to his mechanism for evolution

16. Galåpagos Islands Darwin Wolf Pinta Marchena Genovesa Santiago
Isabela
Darwin
Wolf
Pinta
Marchena
Genovesa
Fernandia
Santiago
Bartolomé
Råbida
Pin zon
Seymour
Baltra
Santa Cruz
Santa Fe
Tortuga
Española
San Cristobal
Floreana
EQUATOR
Galåpagos
Islands

18. Marine Iguana
Land Iguana

19. Evolution Click On Picture For More November 24, 1859
Evolution: the change over time of the genetic composition of populations
Natural selection: populations of organisms can change over the generations if individuals having certain heritable traits leave more offspring than others (differential reproductive success)
Evolutionary adaptations: a prevalence of inherited characteristics that enhance organisms’ survival and reproduction
November 24, 1859

20. Descent with Modification, I
5 observations:
1- Exponential fertility
2- Stable population size
3- Limited resources
4- Individuals vary
5- Heritable variation

21. Descent with Modification, II
3 Inferences:
1- Struggle for existence
2- Non-random survival
3- Natural selection (differential success in reproduction)

22. Mechanism : Natural Selection
Fact 1: Over-reproduction occurs in nature
Fact 2: Populations do not increase exponentially
Fact 3: There are limited natural resources (food, shelter)
These facts are seen in Malthus’ works on populations

23. Fact 4: Variation exists in populations
Inference 1:
struggle for survival ensues
Fact 4: Variation exists in populations
Fact 5: Much of the variation is heritable
Fact 4 was physically observed. Darwin’s weakness was the 5th fact
Inference 2:
Organisms with the best variations survive the struggle for life
Inference 3:
Unequal survival of organisms with different variations leads to favorable variations accumulating over time

24. Key Concepts
What is the raw material necessary for the mechanism of Natural Selection?
Heritable variations
What is the smallest unit of evolution?
Populations
Darwin incorporated Lyell’s gradualism into biological evolution combined with Malthus’ observations regarding populations

25. Evidence for Evolution
Artificial selection
Island biogeography
Fossil record
Taxonomy
Comparative Anatomy
Vestigial Structures
Comparative Embryology
Molecular Biology

26. Natural selection process by which individuals that are better suited to their environment survive and reproduce most successfully. Adaptation is an inherited characteristic that increases an organism’s chance of survival.

27. Evolution evidence: Biogeography
Geographical distribution of species
Examples: Islands vs. Mainland Australia Continents

28. …can lead to reproductive isolation, divergence of gene pools and speciation.

29. Evolution evidence: The Fossil Record
Succession of forms over time
Transitional links
Vertebrate descent

30. Our knowledge about past life comes from fossils, chemical analysis, cores drilled out of buried ice, and DNA analysis.

31. The Fossil Record

32. Evolution evidence: Comparative Anatomy
Homologous structures (homology)
Descent from a common ancestor
Vestigial organs Ex: whale/snake hindlimbs; wings on flightless birds
The ZOO OF YOU…Click on Picture

35. Evolution evidence: Comparative Embryology
Pharyngeal pouches, ‘tails’ as embryos

37. Evolution evidence: Molecular Biology
Similarities in DNA, proteins, genes, and gene products
Common genetic code

38. Final words…... “Absence of evidence is not evidence of absence.”
Review…
Evolution In your Life…
Sexual Cannibalism?
Modern View of Evolution