1. Evolution: History and Evidence
Chapter 4
Evolution: History and Evidence

2. Evolution: History and Evidence
Organic Evolution
Darwin
“Descent with modification”
Populations change over time.

3. Pre-Darwinian Theories of Change
Greek philosophers
Empedocles ( B.C.)
Aristotle ( B.C.)
Buffon ( )
Erasmus Darwin( )
Lamarck ( )
Change results from “need”

4. Voyage of HMS Beagle Charles Darwin (1809-1882) Boarding school
Edinburgh medical school
Christ’s College Cambridge
Nominated by Henslow to serve as naturalist on HMS Beagle (1831)
On Origin of Species by Means of Natural Selection (1859)

5. Figure 4.1 Voyage of the HMS Beagle.

6. Early Development of Darwin’s Ideas of Evolution
Geology
Hutton and uniformitarianism
Geological change occurs over hundreds of millions of years.
Earth is much older than 6,000 years.
Could not living forms change as well?

7. Early Development of Darwin’s Ideas of Evolution
Fossil evidence
South American fossils
Figure 4.2a The giant sloth.

8. Early Development of Darwin’s Ideas of Evolution
Galapagos Islands
Tortoises
Finches
Adaptive radiation
The formation of new forms from an ancestral species
Figure 4.3a Galapagos tortoise (Geochelone elephantopus).

9. Figure 4.4 Adaptive radiation of Galapagos finches.

10. The Theory of Evolution by Natural Selection
Other observations
Artificial selection
Thomas Malthus ( )
(b)
(a)
Figure 4.5 Artificial selection in Canis lupis. The 147 breeds of dogs recognized by the AKC originated from artificial selection of wolf ancestors. The grey wolf (a), Shetland Sheep Dog (b), and Irish Wolfhound (c).
(c)

11. The Theory of Evolution by Natural Selection
High reproductive potential
Inherited variation exists.
Constant struggle for limited resources, many individuals die.
Adaptive traits become more common in subsequent generations.

12. Adaptation
Occurs when a HERITABLE CHANGE IN PHENOTYPE increases an animal’s chances of SUCCESSFUL REPRODUCTION
Examples?
Arise as a result of chance mutations
Perpetuated by natural selection
Figure 4.6 Adaptations of the Arctic Hare (Lepus articus).

13. Alfred Russel Wallace (1823-1913)
Theory of evolution similar to Darwin’s
Published ideas jointly with Darwin
Impetus for Darwin’s publication of On the Origin of Species by Means of Natural Selection
Darwin given credit
Years of work
Massive accumulations of evidence

14. Microevolution, Macroevolution, and Evidence of Macroevolutionary Change
Change in the frequency of alleles in a population over time
Macroevolution
Large-scale changes that result in the extinction and formation of new species

15. Biogeography
Study of the geographic distribution of plants and animals
Life-forms in different parts of
the world have distinctive evolutionary histories.
Biogeographers attempt to explain distribution patterns.

16. Figure 4.7 Biogeography as evidence of evolutionary change.

17. Figure 4.8 Biogeographic regions of the world.

18. Paleontology
Fossils
Evidence of plants and animals that existed in the past and have become incorporated into the earth’s crust
Direct evidence of sequences of appearance and disappearance of organisms

19. Paleontology
Figure The fossil record gives evidence of the horse lineage.
Figure 4.9 Fossils like this trilobite are direct evidence of evolutionary change.

20. Analogy and Homology Convergent evolution Homology
Evolution of superficially similar structures in unrelated organisms
Similar structures are analogous.
Homology
Resemblance that occurs because of common ancestry

21. Homology—Comparative Anatomy
Study of the structure of living and fossilized animals and homologies that indicate close relationships
Figure Vertebrate forelimbs evolved from an ancestral pattern.

22. Figure 4.12 Evolution of the vertebrate ear ossicles.

23. Figure Vestigial structures have no apparent function in an animal, but evolved from functioning structures in ancestors.

24. Homology—Developmental Patterns
Developmental stages of related animals often retain common features.
Changes in genes controlling development are usually harmful and eliminated by natural selection.
Figure Early developmental stages of vertebrates are similar.

25. Homology—Molecular Biology
Study of nuclear DNA, mitochondrial DNA, ribosomal RNA, and proteins
Molecules provide direct evidence of change in genes.
Genetic similarity (degree of relatedness) is reflected in variation in amino acid sequences in proteins and base sequences in DNA.

26. Interpreting the Evidence: Phylogeny and Common Descent
Evolutionary relationships among species

27. Phylogenetic Trees Show lines of descent Branches Nodes
Evolutionary connections
Nodes
Branch points
Genes, populations, or species where a change occurs

28. Modern Synthesis
Principles of modern genetics combined with Darwinian evolutionary theory
Chapter 5