Charles%20Darwin%20

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Charles Darwin Natural Selection
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Lifeline

• Born 1809
• Study (Edinburgh and Cambridge) 1825-1831
• Voyage of the Beagle 1831-36
• Retired to Down 1842
• The Origin of Species 1859
• Died 1882

Darwins home at Down, near London
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Darwins achievements

• Transformed biological science
• Both style and content
• Still the cornerstone of biology
• Now the cutting edge of psychology
• Transformed attitudes of humanity to our place in
  the universe

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Not just an evolutionist

• Not even a biologist to start with
• Collected beetles for fun
• Studied geology more seriously
• Considered himself a geologist throughout the
  Beagle voyage and for some time after
• Famous for working out how coral atolls are formed

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Natural selection

• Developed theory in complete isolation
• In face of violent (religious) opposition
• With no knowledge of genetics
• With no knowledge of DNA
• With no knowledge of plate tectonics
• With no observations of natural selection
  actually occurring

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Joining the Beagle Voyage

• Not paid for 5 years on Beagle.
• Actually, he had to pay!
• Was lucky to get on
• replaced someone who was shot in a duel
• his father opposed him going
• Mainly asked because of his class, to keep
  Captain Fitzroy company
• It was the making of him

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CHARLES DARWIN

• Video Who Was Charles Darwin?

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Galapogos, 1835

• Portrayed as a Eureka experience.
• Actually, was hugely homesick
• Did not recognise significance until back in
  England, 1837.
• Worked out theory much later.
• First inkling of natural selection in 1838.
• Turtles finches were key evidence
• On boat home, ate turtles, dumped shells
• Thought finches different species didnt even
  label them properly

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The Big Idea Natural Selection
Darwins sand walk at Down a daily thoughtful
stroll

• He knew about fossils
• Collected many for extinct animals
• Knew about Lyells theory of evolution of
  geology
• Read Malthus (an economist) on population and
  competition for resources.
• Video Clip
• His ideas developed steadily over 20 years

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Alfred Russel Wallace

• Thought of natural selection independently
• Wrote to Darwin
• Darwin had been working on book
• Published a letter jointly
• It was Darwin who put in the hard yards
  collecting and documenting evidence to support
  theory

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Natural Selection

• Process of change in populations over many
  generations
• Individuals with certain traits survive local
  environmental conditions
• Pass on favourable alleles to offspring
• Environment exerts selective pressure
• This has led to biodiversity

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Assumptions of Natural Selection

• Variation
• -All members of a species display a variety of
  characteristics in their appearance and behavior.
  
• -Many are inherited.

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Assumptions of Natural Selection

• 2. Competition
• The number of offspring produced by individuals
  in a species exceeds the number of offspring that
  will survive to adulthood

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Assumptions of Natural Selection

• 3. Fitness
• Some offspring, because of their differences,
  are better able to adapt to the conditions of the
  environment than others.

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Assumptions of Natural Selection

• 4. Adaptation
• The better-adapted organisms pass on their
  characteristics to their offspring and, as a
  result, the population changes.

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Descent with Modification

• Darwin never used the word evolution in his
  book On the Origin of Species
• Used the term descent with modification instead

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Artificial Selection

• Selective pressure exerted by humans on
  populations
• Improve or modify particular desirable traits
• Eg. Selective breeding in farm animals

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Artificial Selection

• In food crops
• Wheat, corn, rice and veggies have all been
  selectively bred
• Wild mustard plant has been modified to produce
  broccoli, Brussels sprouts, cabbage and
  cauliflower
• Breed for nutritional value, as well as harvest
  yield and pest resistance

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Designer Dogs

• How many breeds of dogs are there now?
• Examples
• What do you get when you cross a Yorkie and a
  Poodle?

Yorkie-poo
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Designer Dogs

• What about a Pug and a Beagle?

Puggle

• Or a Bichon Frize and a Poodle?

Bich-Poo
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Consequences of Artificial Selection

• In dogs respiratory problems (bulldogs) and hip
  dysplasia (labs)
• In crops reduces genetic variation
  (monoculture)