1. EVOLUTION
CHAPTER 15

2. 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 Adapations: a prevalence of inherited characteristics that enhance organisms’ survival and reproduction

3. EVOLUTIONARY HISTORY Linnaeus - taxonomy - Lyell - uniformitarianism
Hutton - gradualism Darwin - evolution
Lamarck - evolution Mendel - inheritance
Malthus - populations Wallace - evolution
Cuvier - paleontology Count Buffon - evolution

4. RESISTANCE TO THE THEORY OF EVOLUTION

5. RESISTANCE TO THE THEORY OF EVOLUTION

6. DARWIN’S INFLUENCES Taxonomy matured during mid-eighteenth century
Linnaeus believed in:
He developed the binomial system of nomenclature
System of classification for living things
Count Buffon:
Wrote 44-volume catalog of all known plants and animals
Suggested descent with modification 6

7. DARWIN’S INFLUENCES Lamarck = First biologist to:
Propose evolution
Link diversity with environmental adaptation
Concluded more complex organisms are descended from less complex organisms: SIMPLE TO COMPLEX
Proposed inheritance of acquired characteristics – Lamarckianism

8. Passing on Acquired Traits

9. DESIRE TO CHANGE

10. Use and Disuse

11. HMS BEAGLE VOYAGE Invited to travel around the world
(22 years old!)
makes many observations of nature
main mission of the Beagle was to chart South American coastline

12. While on the voyage of the HMS Beagle in the 1830s, Charles Darwin observed
similarities between living and fossil organisms
the diversity of life on the Galápagos Islands, such as blue-footed boobies and giant tortoises
Figure 13.1A

13. FINCHES 13

14. MALTHUS Overpopulation and species control
DARWIN’S INFLUENCES
MALTHUS Overpopulation and species control
LYELL
Earth is subject to slow but continuous cycles of erosion
Proposed uniformitarianism, rates and processes of change are constant

15. Darwin became convinced that the Earth was old and continually changing
He concluded that living things also change, or evolve over generations
He also stated that living species descended from earlier life-forms: descent with modification (originally Buffon and Erasmus Darwin)
All organisms are related through decent from an ancestor that lived in the remote past.

16. DARWIN’S 5 MAJOR CONCLUSIONS
1. Population has Variation
2. Variations may be favorable
3. More offspring are produced than survive
4. Survivors have favorable traits
5. Populations change over time

17. ON THE ORIGIN OF SPECIES
......ALL THIS LEADS TO HIS THEORY OF NATURAL SELECTION and SURVIVAL OF THE FITTEST
1859 Publication
Wallace influence

18. WITNESSING NATURAL SELECTION
Early 19th century
Industrial
Revolution

20. Evolution evidence: Fossils

21. The fossil record shows that organisms have appeared in a historical sequence
Many fossils link early extinct species with species living today
These fossilized hind leg bones link living whales with their land- dwelling ancestors
Figure 13.2G, H

22. 2006 Fossil Discovery of Early Tetrapod
Tiktaalik
“missing link” from sea to land animals

23. Evolution evidence: Homologous Structures
Similar structure
Similar development
Different functions
Evidence of close evolutionary relationship
recent common ancestor

24. Homologous structures
spines
leaves
succulent leaves
tendrils
needles
colored leaves

25. Evolution evidence: Analogous Structures
Separate evolution of structures
similar functions
similar external form
different internal structure & development
different origin
no evolutionary relationship
Don’t be fooled by their looks!

26. Evolution evidence: Comparative Embryology

27. Evolution evidence: Vestigial Structures
Modern animals may have structures that serve little or no function
remnants of structures that were functional in ancestral species
deleterious mutations accumulate in genes for non- critical structures without reducing fitness
snakes & whales — remains of pelvis & leg bones of walking ancestors
eyes on blind cave fish
human tail bone

28. Evolution evidence: Molecular Biology
Similarities in DNA, proteins, genes, and gene products
Common genetic code
Closely related species have sequences that are more similar than distantly related species
DNA & proteins are a molecular record of evolutionary relationships

29. Evolution evidence: Biogeography
Fig
Darwin’s observations of biogeography, the geographic distribution of species, formed an important part of his theory of evolution
Islands have many endemic species that are often closely related to species on the mainland
Figure Convergent evolution

30. NATURAL SELECTION IN ACTION
Insecticide & drug resistance
insecticide didn’t kill all individuals
resistant survivors reproduce
resistance is inherited
insecticide becomes less & less effective
The evolution of resistance to insecticides in hundreds of insect species is a classic example of natural selection in action.
The results of application of new insecticide are typically encouraging, killing 99% of the insects.
However, the effectiveness of the insecticide becomes less effective in subsequent applications. The few survivors from the early applications of the insecticide are those insects with genes that enable them to resist the chemical attack. Only these resistant individuals reproduce, passing on their resistance to their offspring. In each generation the % of insecticide-resistant individuals increases.

31. ARTIFICIAL SELECTION
Artificial breeding can use variations in populations to create vastly different “breeds” & “varieties”
“descendants” of wild mustard
“descendants” of the wolf