1. Chapter 15 Intro to Darwin and Evolution

2. 15.1 History of Evolutionary Thought
Biology, 9th ed,Sylvia Mader
Chapter 17
15.1 History of Evolutionary Thought
Darwin and Evolution
Prior to Darwin
The view of nature was determined by deep-seated beliefs held to be intractable truths rather than experimentation and observation
Biologists had slowly begun to accept various ideas of evolution (species change through time)
Evolution is the unifying principle of biology
Explains the unity and diversity of life
Similarities between living things reflect recent common ancestry
Dissimilarities between living things reflect ancient common ancestry

3. History of Evolutionary Thought
Biology, 9th ed,Sylvia Mader
History of Evolutionary Thought
Chapter 17
Darwin and Evolution
Mid-Eighteenth Century Influences:
Taxonomy matured during the mid-eighteenth century
Linnaeus believed in the fixity of species
Each species had:
An ideal structure and function, and
A place in the scala naturae (a sequential ladder of life)
Count Buffon:
A French naturalist
Provided evidence of descent with modification
Suggested mechanisms including environmental influences, migration, geographic isolation, and the struggle for existence

5. History of Evolutionary Thought
Biology, 9th ed,Sylvia Mader
Chapter 17
History of Evolutionary Thought
Darwin and Evolution
Late Eighteenth Century Influences:
Cuvier:
Founded the science of paleontology
Proposed catastrophism
Local catastrophes in the past had caused the Earth’s strata to have a new mix of fossils
After each catastrophe, the region was repopulated by species from surrounding areas
The result of the catastrophes was change appearing over time

6. History of Evolutionary Thought
Biology, 9th ed,Sylvia Mader
Chapter 17
History of Evolutionary Thought
Darwin and Evolution
Late Eighteenth Century Influences:
Lamarck:
First biologist to:
Propose evolution
Link diversity with environmental adaptation
Proposed the inheritance of acquired characteristics – Lamarckianism
Charles Lyell:
Earth is subject to slow but continuous cycles of erosion and uplift
Proposed uniformitarianism, which states that rates and processes of change are constant

7. Darwin’s Theory of Evolution
Biology, 9th ed,Sylvia Mader
Chapter 17
Darwin’s Theory of Evolution
Darwin and Evolution
Geological observations consistent with those of Hutton & Lyell
Biogeography:
The study of the geographic distribution of life forms on earth
Darwin saw similar species in similar habitats
Reasoned that related species could be modified according to the environment
Living forms could be descended from extinct forms known only from the fossil record
What Darwin Never Knew

8. Animals of South America Encountered by Darwin
Biology, 9th ed,Sylvia Mader
Chapter 17
Animals of South America Encountered by Darwin
Darwin and Evolution

9. Darwin’s Theory of Evolution
Biology, 9th ed,Sylvia Mader
Chapter 17
Darwin’s Theory of Evolution
Darwin and Evolution
Galapagos Islands
Tortoises
Darwin observed that tortoise neck length varied from island to island
Proposed that speciation on islands correlated with a difference in vegetation
Finches
Darwin observed many different species of finches on various islands
Significant variety in beaks
Speculated that they could have descended from a type of mainland finches

10. Biology, 9th ed,Sylvia Mader
Chapter 17
Galápagos Tortoises
Darwin and Evolution
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. a. b.
a: © Kevin Schafer/Corbis; b: © Michael Dick/Animals Animals/Earth Scenes

11. Darwin’s Theory of Evolution
Biology, 9th ed,Sylvia Mader
Chapter 17
Darwin’s Theory of Evolution
Darwin and Evolution
Natural Selection and Adaptation:
Members of a population have inheritable variations
More individuals are produced in each generation than environment can support
Some individuals have adaptive characteristics
Favorable traits that result in increased survival and reproduction
Natural selection can result in a population adapted to the local environment
An increasing proportion of succeeding generations will have favorable characteristics

12. Darwin’s Theory of Evolution
Biology, 9th ed,Sylvia Mader
Chapter 17
Darwin’s Theory of Evolution
Darwin and Evolution
Darwin emphasized that individuals from a population vary in their:
Functional characteristics
Physical characteristics
Behavioral characteristics
He proposed that these variations:
Occur randomly
Are essential to the natural selection process
Allow adaptation to the environment over time

13. Darwin’s Theory of Evolution
Biology, 9th ed,Sylvia Mader
Chapter 17
Darwin’s Theory of Evolution
Darwin and Evolution
Fitness is the relative reproductive success of an individual
The most-fit individuals in a population capture a disproportionate share of goodies
Interactions with the environment determine which individuals reproduce the most
Adaptation
Change that helps a species become more suited to its environment
Product of natural selection

14. Darwin’s Theory of Evolution
Biology, 9th ed,Sylvia Mader
Chapter 17
Darwin’s Theory of Evolution
Darwin and Evolution
Artificial selection
A breeder chooses which traits to perpetuate and selects the plants and animals that will reproduce
All dogs are descended from the gray wolf
Began to be domesticated about 14,000 years ago.
The process of diversification led to extreme phenotypic differences
The wolves under domestication were separated from other wolves.
Each human tribe selected for whatever traits appealed to them.

15. Artificial Selection of Animals
Biology, 9th ed,Sylvia Mader
Artificial Selection of Animals
Chapter 17
Darwin and Evolution
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 
Irish
wolfhound
How the Gray Wolf Become Man's Best Friend
Wolf

16. Darwin’s Theory of Evolution
Biology, 9th ed,Sylvia Mader
Chapter 17
Darwin’s Theory of Evolution
Darwin and Evolution
Darwin’s natural selection hypothesis was based on Observation of tortoises and finches on the Galápagos Islands.
Each of the 13 species of Galápagos finches has a beak adapted to a particular way of life.
A heavy beak is suited to a diet of large seeds
The beak of the warbler-finch is suited to feeding on insects
A longer, somewhat decurved beak and the split tongue of the cactus-finch are suited to probing a cactus for seeds

17. Biology, 9th ed,Sylvia Mader
Chapter 17
Evolution in Action
Darwin and Evolution
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
wet year
dry year
dry year
dry year
Beak Depth
medium
ground finch
1977
1980
1982
1984
Rosemary and Peter Grant (Galapagos Finches)

18. 15.3 Evidence for Evolution
Biology, 9th ed,Sylvia Mader
Chapter 17
15.3 Evidence for Evolution
Darwin and Evolution
Fossil evidence
Fossils are the remains and traces of past life or any other direct evidence of past life such as trails, footprints, or preserved droppings
Fossils record the history of life from the past
Document a succession of life forms from the simple to the more complex
Sometimes the fossil record is complete enough to show descent from an ancestor
Transitional fossils are a common ancestor for two different groups of organisms
They allow us to trace the descent of organisms

19. Biology, 9th ed,Sylvia Mader
Transitional Fossils
Chapter 17
Darwin and Evolution
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Amphibian
tetrapod
Early
amphibian
360
Expanded ribs
Neck
Flat head,
eyes on top
Millions of years ago (mya)
370
Scales
Tiktaalik
roseae
Fins
377
380
Rounded head,
eyes on sides
Fish

20. Anatomical Transitions During the Evolution of Whales
Biology, 9th ed,Sylvia Mader
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Chapter 17
Anatomical Transitions During the Evolution of Whales
Darwin and Evolution
a. Ambulocetus
50 mya
b. Basilosaurus
40 mya
modern
c. Right whale
a: © J.G.M. Thewissen,

21. Evidence for Evolution
Biology, 9th ed,Sylvia Mader
Chapter 17
Evidence for Evolution
Darwin and Evolution
Biogeographical Evidence:
Biogeography is the study of the range and distribution of plants and animals throughout the world
Biogeographical distributions are consistent with the hypothesis that related forms of life evolved in one locale and then spread to accessible regions

22. Evidence for Evolution
Biology, 9th ed,Sylvia Mader
Chapter 17
Evidence for Evolution
Darwin and Evolution
Anatomical Evidence:
Vertebrate forelimbs:
Homologous structures - All contain the same sets of organized bones in similar ways
Yet they are modified extensively to meet various adaptive needs
Darwin interpreted this as support for a hypothesis of common descent
Embryological development
All vertebrate embryos have:
A postanal tail and
Paired pharyngeal (gill) pouches

23. The Evidence of Evolution
Biology, 9th ed,Sylvia Mader
Chapter 17
The Evidence of Evolution
Darwin and Evolution
Homologous Structures:
Anatomically similar because they are inherited from a common ancestor
May be functionally similar or not
Analogous Structures:
Serve the same function
Are not constructed similarly
Do not share a common ancestor
Vestigial Structures:
Fully-developed anatomical structures in one group of organisms
Reduced or obsolete function in similar groups
Vestigial Structures in Humans

24. Significance of Homologous Structures
Biology, 9th ed,Sylvia Mader
Chapter 17
Darwin and Evolution
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
bird
humerus
ulna
radius
metacarpals
phalanges
bat
whale
cat
horse
human

25. Significance of Developmental Similarities
Biology, 9th ed,Sylvia Mader
Chapter 17
Significance of Developmental Similarities
Darwin and Evolution
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
fish
salamander
tortoise
chick
pharyngeal
pouches
human
postanal
tail

26. Evidence for Evolution
Biology, 9th ed,Sylvia Mader
Chapter 17
Evidence for Evolution
Darwin and Evolution
Biochemical Evidence:
All living organisms:
Use the same basic biochemical molecules
Utilize same DNA triplet code
Utilize same 20 amino acids in their proteins
DNA base-sequence differences:
When very similar, suggest recent common descent
When more different, suggest more ancient common descent

27. Significance of Biochemical Differences
Biology, 9th ed,Sylvia Mader
Chapter 17
Significance of Biochemical Differences
Darwin and Evolution
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
yeast
moth
fish
turtle
duck
pig
monkey
human 10 20
Number of Amino Acid Differences
Compared to Human Cytochrome c 30
Cytochrome c is a small protein
that plays an important role
in the electron transport chain
within mitochondria of all cells. 40 50