Evolution fill in notes: Questions 1 & 2
Q#1: - What is evolution?
My Answer: Evolution is change over time
Scientists answer: The idea that all organisms are related.
Jot down key ideas/words/phrases as the scientists share: common descent, related, things
change
Evolution is not just a theory; it is a process that happens over long periods of time.
Label the following:
4.5 bya
3.6 bya
Earth formed evidence of life
1.6 bya
eukaryotes
.6 bya
animals
humans
List three questions evolution attempts to explain:
1. How does life change over time?
2. How does the environment change?
3. How do things get where they are?
Q #2: – Who is Charles Darwin?
Darwin’s background/key points:
College graduate that was on his way to being a clergyman but got hired to work as a naturalist on the
HMS Beagle. Darwin was a creationist when he first visited.
Why are the Galapagos Islands so important? You can see the process of evolution happening.
Darwin originally believed that organisms never changed (fixity of species/creationism0 and that a
species were organisms that looked and behaved alike.
Theories of evolution before Darwin:
Erasmus Darwin: All organisms arose from a common ancestor.
Lamarck: individuals in a species change in response to their environment.
How did Darwin propose birds got from the mainland to the various islands: a storm blew the birds to
different islands.
What happened to them on the islands? They became different species over time.
Darwin hypothesized that the finch on all islands originally came from a common ancestor.
This change over time became his theory of evolution but what was the mechanism/means that caused
the changes?
Malthus: there is a constant struggle between food supply (changed rapidly) and the # of organisms
(changed gradually).
Darwin states add in variation (differences within a species) and you get natural selection
Darwin’s “Big Idea”: All organisms evolve through natural selection and have descended from a common
ancestor.
Q#3: – What is natural selection?
Definition #1: process by which organisms that have beneficial traits survive in its environment and
reproduce.
Definition #2: A difference in survival & reproduction rates as a result of the interaction of some feature
of the organism and some features of the environment.
Survival of the fittest means: best able to survive
Does not mean: strongest
Current example of evolution: Peter and Rosemary Grant observe Galapagos Island finch over 32 year
period
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After a drought they found that the large finch survived because of the ability to crush hard
seeds with a large, strong beak.
Over 20-25 years the birds the population evolved into 2 different species, one with large
beaks and one with small beaks. The medium sized beaks disappeared, why? It wasn’t
favorable in the environment.
Sexual selection: a trait that attracts a mate or establishes dominance.
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Examples: peacock feather, bright red feathers of a cardinal.
Define and give an example:
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Overproduction: more produced than can ever survive; ex: seeds
Limited Resources: supplies cannot sustain a given population; ex: Oh, Deer
Variations: changes within a certain trait; ex: eye color
****Define natural selection in your own words: A process by which organisms with favorable traits
survive and reproduce.