EVOLUTION

1
EVOLUTION

• A SCIENTIFIC THEORY

2
I. The History

• Carl Linneaus (18th century) The father of
  taxonomy. Used binomial nomenclature, came up
  with the hierarchical classification theme, used
  visible characteristics to classify plants and
  animals.
• Thomas Malthus (18th 19th century) Attempting
  to justify the conditions of the poor by stating
  that poverty and starvation were merely a
  consequence of overpopulation.
• http//www.pbs.org/wgbh/evolution/library/02/5/l_0
  25_01.html

3

• Lamarck (18th 19th century) First to publish
  a reasoned theory of evolution A) the idea of
  use and disuse B) inheritance of acquired
  characteristics
• Lyell (19th century) natural processes form
  geological formations over a long period of time,
  erosion and other forces that shape rocks are
  very slow processes that take millions of years,
  so the earth must be older than previously
  believed.
• Wallace (19th 20th century) theory of
  evolution by natural selection.

4

• Charles Darwin (19th century) theory of
  evolution by natural selection.

5
II. What is a scientific theory?

• A widely accepted explanatory idea that is broad
  in scope and supported by a large body of
  evidence.
• http//www.pbs.org/wgbh/evolution/library/11/2/e_s
  _1.html

6
III. Natural Selection

• Natural Selection The process in nature by
  which, only the organisms best adapted to their
  environment tend to survive and transmit their
  genetic characteristics in increasing numbers to
  succeeding generations while those less adapted
  tend to be eliminated. As a result the
  POPULATION EVOLVES or changes over time.

7

• The five aspects (steps) of natural selection
• Variation individuals exhibit variation in a
  population, they have a unique set of traits.
  Some of these traits improve their chances of
  survival while others are less favorable.
• Overproduction populations produce too many
  young, many must die.
• Struggle for existence food, water and other
  resources are limited, organisms are compete with
  one another for these resources.

8

• Differential reproductive success those
  individuals that have the most favorable
  characteristics in an environment, has higher
  chance of reproduction.
• Descent with modification the varying
  reproductive success result in a change in the
  population the more successful traits become
  more common
• http//www.pbs.org/wgbh/evolution/library/01/6/qui
  cktime/l_016_08.html
• http//www.pbs.org/wgbh/evolution/library/01/6/l_0
  16_09.html

9
IV. Evidence of Evolution

• The fossil record remains or traces of
  previously lived organisms (shells, amber,
  prints, skeletal remains). Mostly found in
  sedimentary rocks
• Their age can be determined by radiometric dating
• http//www.pbs.org/wgbh/evolution/library/03/3/l_0
  33_01.html

10

• Comparative anatomy homologous structures
  structures that have similar origins but may look
  different from the outside. Analogous structures
  -- may look similar but have different origins

11
(No Transcript)
12

• Vestigial structures structures that are not
  used any more but were used by our ancestors
• Biogeography of animals and plants and
  continental drifts (geographic distribution of
  species) organisms with similar origin tend to
  live in the same area
• http//www.ucmp.berkeley.edu/geology/anim1.html
  -- so similar fossils from different continents
  could be found
• Developmental biology the embryos of related
  species look similar during their early embryonal
  development.

13
(No Transcript)
14

• Artificial selection humans select traits of
  organisms for human benefits (domestication)
• Molecular comparisons
• Universal genetic code
• Proteins and DNA (the closer related two species
  are the more similar their DNA and proteins are)
• Molecular clocks
• Biogeography geographic distribution of
  species.

15
(No Transcript)
16
V. The Mechanisms of Evolution

• Natural selection you already know this one.
• Mutations (small changes in the nucleotide
  sequence of DNA) result in new traits and
  increasing variation in the population. One
  mutation alone usually does not change the
  population, however, beneficial mutations can
  cause some change

17

• Genetic drift change in the allele frequency in
  a population based on chance
• Founder effect small group of organisms move
  away from the main population and give rise to a
  new population
• Bottleneck effect after a natural disaster, a
  small group of organisms with different
  characteristics survive

18

• Gene flow movement of organisms from one
  population to another
• Nonrandom mating sexual selection, selecting
  mates because of their visual traits.
• http//www.youtube.com/watch?vcEh-zclVo44

19
VI. Examples of Evolution

• Industrial Melanism
• Human birth weight
• Heterozygous advantage
• Darwins finches
• Antibiotic and pesticide resistance

20
VII. Modern Evolutionary Theory

• Several scientists improved on Darwins theory
  and this improvement is still going on.
• We know that POPULATIONS EVOLVE NOT INDIVIDUALS
• Today we explain the causes of evolution with
  mutations, changes in DNA and sexual
  reproduction.
• Evolution is closely related to genetics.
• http//www.pbs.org/wgbh/evolution/library/03/4/l_0
  34_04.html

21

• Todays definition of evolution Genetic change
  in a population or species over generations all
  the changes that transform life on Earth these
  heritable changes produced Earths diversity of
  organisms
• Just for fun http//www.youtube.com/watch?vT1_vn
  sdgxII