The Development of Evolutionary Theory

1
Chapter 2

• The Development of Evolutionary Theory

2
Chapter Outline

• A Brief History of Evolutionary Thought
• The Discovery of Natural Selection
• Natural Selection
• Natural Selection in Action
• Constraints on Nineteenth-Century Evolutionary
  Theory
• Opposition to Evolution Today

3
Natural Selection

• The most critical mechanism of evolutionary
  change, first articulated by Charles Darwin
  refers to genetic change or changes in the
  frequencies of certain traits in populations due
  to differential reproductive success between
  individuals.

4
Fixity of Species

• The notion that species, once created, can never
  change an idea diametrically opposed to theories
  of biological evolution.

5
Aristotles Worldview

• This beautifully illustrated seventeenth-century
  map shows the earth at the center of the solar
  system.
• Around it are 7 concentric circles depicting the
  orbits of the moon, sun, and the 5 planets that
  were known at the time.

6
Pre-scientific View

• In the middle ages, the predominant world was
  stasis, the world was fixed and unchanging.
• The great chain of being held that life was
  arranged from simplest to most complex.
• It was believed that the earth was full and
  nothing new could be added.
• The world was seen as the result of a grand
  design - Gods design.

7
Reproductively Isolated

• Pertaining to groups of organisms that, mainly
  because of genetic differences, are prevented
  from mating and producing offspring with members
  of other groups.

8
Binomial Nomenclature

• In taxonomy, the convention established by
  Carolus Linnaeus whereby genus and species names
  are used to refer to species.
• For example, Homo sapiens refers to human beings.
  
• Taxonomy is the branch of science concerned with
  the rules of classifying organisms on the basis
  of evolutionary relationships.

9
Evolution

• A change in the genetic structure of a
  population.
• Also refers to the appearance of a new species.
• Often controversial, some religious views hold
  that evolutionary statements run counter to
  biblical teachings.

10
Lamarck

• John Baptiste Lamack was the first scientist to
  produce an explanation for the evolutionary
  process.
• He believed that species change was influenced by
  environmental change.

11
Cuvier

• Georges Cuvier introduced the concept of
  extinction and the theory of catastrophism.

12
Thomas Malthus

• Thomas Malthus wrote about the relationship
  between food supply and population increase.
• His essay on the Principle of Population led both
  Darwin and Wallace to the principle of natural
  selection.

13
Charles Lyell

• Charles Lyell developed the theory of
  uniformitarianism.

14
Catastrophism

• The view that the earths geological landscape is
  the result of violent cataclysmic events.
• Cuvier promoted this view, especially in
  opposition to Lamarck.

15
Uniformitarianism

• The theory that the earths features are the
  result of long term processes that continue to
  operate in the present as they did in the past.
• Elaborated on by Lyell, this theory opposed
  catastrophism and contributed strongly to the
  concept of immense geological time.

16
Mary Anning

• Discovered the first complete fossil of
  Ichthyosaurus, a large fishlike marine reptile.
• She became known as one of the worlds leading
  fossilists and contributed to the
  understanding of the evolution of marine life
  over 200 million years ago.

17
Charles Darwin

• Charles Darwin, photographed 5 years before the
  publication of Origin of Species.

18
Question

• One of the world's leading "fossilists" who
  contributed to the understanding of the evolution
  of marine life over 200 million years was
• Mary Anning.
• Lyell.
• John Ray.
• Darwin.

19
Answer a

• One of the world's leading "fossilists" who
  contributed to the understanding of the evolution
  of marine life over 200 million years was Mary
  Anning.

20
Question

• The person credited with removing the earth as
  the center of the universe is
• Buffon.
• Lamarck.
• Copernicus.
• Archbishop James Ussher.

21
Answer c

• The person credited with removing the earth as
  the center of the universe is Copernicus.

22
Evolution Is a Theory

• The theory has been supported by a mounting body
  of genetic evidence.
• The theory has stood the test of time.
• The theory stands today as the most fundamental
  unifying force in biological science.

23
The Scientific Revolution

• Discovery of the new world challenged fundamental
  views about the planet.
• Exposure to new plants and animals increased
  awareness of biological diversity.

24
The Scientific Revolution

• Copernicus challenged the idea that the earth was
  the center of the universe.
• Galileos work supported the idea that the
  universe was a place of motion.
• Keppler, Descartes and Newton established the
  laws of physics, motion and gravity.

25
Precursors to the Theory of Evolution

• John Ray provided first definition of the concept
  of species and genus.
• Carolus Linnaeus developed system of
  classification and the basis for taxonomy.
• Comte de Buffon stressed the importance of change
  in the universe and the environment as an agent
  of change.

26
Charles Darwin (1809-1882)

• Ideas were formed while serving as a naturalist
  on the voyage of the HMS beagle.
• Darwin saw the importance of biological variation
  within a species.
• Recognized the importance of sexual reproduction
  in increasing variation.
• By 1844, Darwin had complete the work that he
  would publish fifteen years later.

27
The Path of the HMS Beagle
28
Darwins Galápagos Finches

• Beak Variation

29
Domestic Dog Breeds

• The variation exhibited by dog breeds has been
  achieved in a relatively short time through
  artificial selection.

30
Alfred Russell Wallace(1823-1913)

• A naturalist who worked in South America and
  Southeast Asia.
• Suggested species descended from other species
  and new species were influenced by environmental
  factors.
• Presented paper on evolution and natural
  selection to the Linnean Society of London
  jointly with Darwin.

31
Contrasting Views on Evolution
32
Contrasting Views on Evolution
33
Question

• Darwin recognized that individuals were unique.
  He realized that ________ could explain how
  selection occurred.
• variation
• strength
• altitude
• time

34
Answer a

• Darwin realized that variation among individuals
  was how selection occurred, ultimately causing
  change in species

35
Processes of Natural Selection

1. Species can produce offspring at a faster rate
   than food supplies increase.
2. There is biological variation within all species.
   
3. In each generation, more individuals are produced
   than can survive.

36
Processes of Natural Selection

1. Individuals that possess favorable traits or
   variations are more likely to survive and produce
   offspring.
2. Environmental context determines whether a trait
   is beneficial.
3. Traits are inherited and passed on to the next
   generation.

37
Processes of Natural Selection

1. Variations accumulate over long periods of time,
   so later generations may be distinct from
   ancestral ones.
2. As populations respond to pressures over time,
   they may become distinct species, descended from
   a common ancestor.

38
Natural Selection in Action

• Variation in the peppered moth.
• (a) The dark form is more visible on the light,
  lichen-covered tree.
• (b) On trees darkened by pollution, the lighter
  form is more visible.

39
Question

• Selective forces come from
• individuals.
• genetics.
• populations.
• the environment.

40
Answer d

• Selective forces come from the environment.

41
Evolutionary Change Through Natural Selection

1. A trait must be inherited if natural selection is
   to act on it.
2. Natural selection cant occur without population
   variation in inherited characteristics.
3. Fitness is a relative measure that changes as the
   environment changes.
4. Natural selection can only act on traits that
   affect reproduction.

42
Christian Fundamentalists

• Adherents to a movement in American Protestantism
  that began in the early twentieth century.
• This group holds that the teachings of the Bible
  are infallible and are to be taken literally.