Evolution:

1
Evolution

• Why Are There So Many
• Living Things?

2
Where Did the Idea of Evolution Come From?

• Middle Ages
• Ladder of Life
• Complex organisms found at highest rungs
• Less complex at lower rungs
• 1800s
• Georges Cuvier brought study of fossils to the
  level of science.

3
Where Did the Idea of Evolution Come From?

• Charles Lyell
• Proposed theory of uniformitarianism.
• Jean-Baptiste Lamarck
• Published theory of the inheritance of acquired
  characteristics.

4
Charles Darwin

• Loved nature
• Studied medicine
• Struggled with the inhumane operating procedures
• Switched to religion
• Offered position as naturalist on British survey
  ship, The Beagle.

5
Voyage around the World

• Studied animals and fauna.
• Noticed South American fossils differed from
  contemporaries.
• Collected data for 27 years to support his
  mechanism for evolution.

6
Fathers of Evolution

• Alfred Wallace studied in Brazil and East Indies.
  
• Developed mechanism of evolution independently of
  Darwin.
• Sent a copy of it to Darwin.
• Contained same conclusions as Darwin
• Both presented their data at Linnaean Society of
  London in July 1858.

7
How Did Darwin Account for Species?

• In Origin of Species, he developed two main
  concepts
• Evidence that evolutions has occurred.
• Mechanism for evolution natural selection.

8
Major points of Darwins theories of evolution
and natural selection

• First observation
• Populations have the potential to increase
  exponentially.
• Based on thoughts by Thomas Malthus

9
Major points of Darwins theories of evolution
and natural selection

• Second observation
• Populations are fairly constant in size.

10
Major points of Darwins theories of evolution
and natural selection

• Third observation
• Natural resources are limited.
• Limited amount of space, nutrients, shelter
• Results in competition for resources to survive.

11
Major points of Darwins theories of evolution
and natural selection

• Deduction one
• Only some organisms survive. There is a struggle
  for existence among individuals in a population.
• Organisms posses characteristics that enhance
  survival
• Called adaptations.

12
Three Types of Adaptations

• Morphological-anatomical modifications in form
  and structure that enhance survival.
• Biochemical-physiological modifications in the
  production and use of chemicals by organisms.
• Behavioral Adaptations Modifications in animal
  interactions with others and environment.

13
Major points of Darwins theories of evolution
and natural selection

• Fourth observation
• There is variation within individuals of a
  population and variations are inherited.

14
Major points of Darwins theories of evolution
and natural selection

• Deduction two
• Individuals with favorable variations are more
  likely to survive and reproduce.
• Natural Selection
• preservation of favorable variations and the
  rejection of injurious variations

15
Major points of Darwins theories of evolution
and natural selection

• Deduction three
• Accumulation of inheritable variation over many
  generations is evolution.
• If changes within a species become great enough,
  a new species can result.

16
What is a species?

• Species are considered extinct if they do not
  interbreed in nature.
• Implies offspring must also be able to reproduce.

17
Evidence supporting Theory of Evolution

• Selective breeding practices used by farmers
  result in
• improved domesticated plants and animals.
• Darwin wondered if nature could do the same.

18
Evidence supporting theory of evolution

• Fossil record
• Comparing fossils from ancestors with todays
  species demonstrates species have evolved.

19
Evidence supporting theory of evolution

• Homologous structures
• Structures dissimilar in form and function.
• but share underlying structural similarities
• Similarity due to a common ancestor?