Darwin

1
Darwin Evolution
Charles Darwin as a young man.
California Standards 8.a d.
2
What was Darwins early life like?
3
(No Transcript)
4
Ideas that Influenced Darwin

• Thomas Malthus suggested that populations
  increase faster than food supplies
• Alfred Russel Wallace asked Darwin to help him
  publish his essay on evolution so Darwin also
  published his ideas.
• Lamarck said that structures increase in size
  because of use, or decrease in size because of
  disuse. (Theory of Use and Disuse)

5

• Lamarck believed that a giraffes neck became
  longer from stretching to reach higher for food
  and that the longer neck could be inherited by
  offspring.

Long necks because of higher trees.
6
Charles Darwin

• Darwin was the ships naturalist on the HMS
  Beagle.
• He traveled for 5 years keeping a record of the
  plants and animals he observed.
• He developed ideas about evolution but did not
  share them for many years.

Charles Darwin as an old man.
7
Journey of the H.M.S. Beagle on its 5 year
journey in 1831.
8
How did the animals and plants on the Galapagos
Islands get there? Insular ecology is the study
of populations on islands.
9
The Origin of Species published by Charles
Darwin in 1859. This book changed how science
looked at the natural world from that time on. It
was the most important publication in modern
scientific times.
10
Natural Selection

• Darwin said, Individuals that have physical or
  behavioral traits that better suit to their
  environment are more likely to survive and
  reproduce than those that do not have such
  traits.

11
Galapagos Finches
A new species of finch evolved by using resources
on the island that other birds were not using.
12
What is a species?
Answer when two similar organisms can no longer
breed then they are considered a new species.
They must also produce fertile offspring.
13
Natural Selection base upon divergence in the
history of an animal.
14
Four Points to Support the Theory of Evolution

• 1. Variation exists within species
• 2. Some individuals are more likely to survive
  than others.
• 3. Desirable traits in a population spread over
  time.
• 4. Fossils suggest that living species evolved
  from species that are extinct.

15

• Natural selection-the process by which
  populations change in response to their
  environment because of genetic variation
• Adaptation-the changing of a species that results
  in its being better suited to its environment.

16
The Evolution of a Species

• NOTE Change does not occur because the
  environment changes, but rather individuals
  survive environmental change as a result of their
  own genetic change.

- The animal/plant will exploit the resources in
the environment that are most abundant.
17
Darwins Updated Ideas

• 1. Natural selection causes change within
  populations-frequency of alleles may increase or
  decrease in time
• 2. Isolation leads to species formation-species
  that are separated from each other evolve
  differently until they cannot interbreed (new
  species)
• 3. Extinction leads to species replacement-species
  that are better suited to the environment
  replace those that become extinct

18
Genetic mutations can give rise to new species.
A common ancestor gave rise to the species Canine
19
Elephant-Shrew Nature gone wild?