My notes are based on lecture notes that have been taken in class, as well as including other information from a biology textbook, the notes include, Darwins Theory of Evolution, Natural selection as well as evidence to support these theories.
CHAPTER 15 : Darwin and Evolution
- OUTCOMES:
• Identify historical figures and their viewpoints before and during the
development of Darwin’s theory.
• Describe Darwin’s trip aboard the HMS Beagle and some of the observations
that he made
• Describe Darwin's theory of Evolution
• Explain the Concepts of Natural Selection and Adaptation
- Summaries the Theory:
• Natural Selection is based on:
- Variation
- Competing for available resources
- Differ in terms of reproductive success
- Adapted to conditions
• Interpret one example from each of the study as evidence supporting the
decent of all life from a common ancestor
• intemperate misconceptions of evolution proposed by Darwin’s critics
AUDIO CLIP 1:
Discussing Darwin's Theory of Evolution
- Combination of the learning objective 2,3 and 4
- Although it was not Darwin's original idea, he begun collecting evidence during his
voyage that organisms are related through descent with modification (What
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,Notes by: Shai Thursday, October 6, 2022
does decent with modification mean?) from a common ancestor ( What is the
definition of a common ancestor?) and that adaptation to various environments
results in diversity ( What does diversity mean? )
- Read more about it in the textbook
- Look at the word common ancestor, everything on earth, all living organisms can
be traced back to a common ancestor, so we are all related but we all don’t look
the same because of diversity, adaptation and modification.
- Diversity is there because of Adaptation, and Adaptation, is of modification from
a common ancestor (NB TO REMEMBER)
- The Galapagos Islands: Read about this in the text book
• these are the island in which Charles Darwin found evidence of evolution he
looked at two different animals
• one being the Galapagos tortoises and the second being the Galapagos finches
- TORTOISES:
• Darwin observed that the tor. neck varied in length from island to island
• proposed that SPECIATION on the islands correlated to a difference in
vegetation
- LONG NECK AND SHORT NECK
- long neck: in areas where vegetation lower down like shrubs were minimal
BUT abundance of hight cacti
- short neck: in areas where vegetation higher up was minimal BUT
vegetation like shrubs and foliage was abundant
- FINCHES:
• Darwin observed many different species of Finches on various islands
• significant variety on beak sizes and shapes
2
, Notes by: Shai Thursday, October 6, 2022
• it was speculated that they could have been descendants from a type of
mainland finches (But how did they get there and what is this term
called?, How does this term lead to speciation? )
- Each finches beak varied in shape and size, this meant that there could
have been different foods on different parts of the island.
- IMPORTANT WORDS THAT WE NEED TO KNOW:
• Common Ancestor = Geographical Barrier = Adaptation = Origin of a new
species
- Geographical Barrier: on Earth (millions of years ago ) a barrier would be
an ocean, a mountain range ect.
- lets say you have two different groups of animals ( that came from the
same COMMON ANCESTOR) that are now separated by barrier
- the whole ecological niche is different over the years you will get two
specific populations that will adapt to two different sets of environments
and that is how you would get two new species.
- NATURAL SELECTION AND ADAPTATION:
- Alfred Russel ( he came up with the same theories, please remember his name)
Wallace and Darwin: in 1858, they presented their findings to the Linnaean Society
of London
• Natural Selection
- Variation: in order for you to have natural selection you need variation this
means, that within an organism or a pop. there needs to be this variation not
all can be the same
- Competition for available resources: org. in the same environment have to
compete for the same resources, because they are all diff. they are not all at
the same level of success
- differ in terms of reproductive success: the individuals that produce the most
offspring are more successful and will be able to take their genes to the next
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