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BIOB51H3 Lecture Notes - Special Creation, Aphid, Binomial Nomenclature

Biological Sciences
Course Code
Maydianne Andrade

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Lecture 02
Before Darwin
3 big questions :
o How did life rise
o What accounts for the diversity of species
o Why are organisms so well suited to their environments (how do we explain adaption)
ANSWER to these question = Special Creation
o Which can be seen as the historical view that used to explain biodiversity and adaption
before Darwin
Judeo-Christian-Muslim traditions,1800s - idea was that we can understand the natural world
through this framework that all species are:
o Created independently (separately from each other)
o Do not change through time (way you saw them in 1800 were same as they must be in
the past)
o Created recently and at the same time (earth and life are young)
traditional view held this sort of idea for life the mechanism is via supernatural force
meaning something outside of natural laws that you could observe on a day to day
BUT even before Darwin wrote Origin of species 3 observations began to suggest the frame
work didn’t work:
1. Species change over time
a. found fossils that species did change over time
2. Extinction
a. there were things around in the past that were longer no presented now
3. Time-series of species appearance
a. as they began to look at geological column (= strata of rocks that make the crest of
earth), they found fossil that changed over time & the different species they found
on earth appear at different points in the geological timeline
4. Environments had changed over time
a. a point that is important but wasn’t recognize by everyone
b. evidence of environmental change over time was found geologist were showing
areas that were currently mountain that were used to be under ocean , areas
previously wet are dry and vice versa all indicating radical environmental change
over time
Alfred Wallace - why the 4th point is important because it challenged the idea was that if all
organisms were created at the one time but environment changed since then thus, why are
organism still adapted to their environments
o can’t use special creation to explain adaption at present time by organism because
environment had changed since time it was created)
5. Relatedness of species (similarity w/in diversity; tree of life)
a. people were beginning to suspect that species were independent of each other
grouped similarity they were seeing was from some form of relatedness b/w
b. had idea that maybe similarity was inherited from common ancestor (e.g. tree of

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These observations were making people question the historical traditional as explanation for
life and biodiversity
e.g. Classification of Beetle (similarity suggest organism are related)
o classification came before Darwin Linnaeus came up w/ Binomial nomenclature and
began to categorize organism according to their similarity
o (don’t memorize this) Eukaryotes Metazoa Arthropoda insecta
Endopterygota Coleoptera
Darwin and others insight was the these clusters of similarity for e.g. eukaryotes have true
nuclei they are classes of similar traits that define organism people were beginning to
suspect these traits were inherited from common ancestors
the environment in which Darwin was coming up w/ his ideas was when special creation was
still dominant view point , new ideas were developing in the scientific community based on the
observations that suggest species change over time, species derive from common ancestor, and
earth and life are old
o these ideas were challenges to special creation but these new ideas had nothing to
say about adaption only about life and diversity
Early definition (before Darwin) of evolution was that you had the development of new types of
living organism from pre-existing types (different from historical )
so evolution was proposed instead of special creation to better understand life and diversity of
o But evolution proposed until Darwin & Wallace could not explain adaption ( how well
organism are fit to the changing environment)
Darwin’s key contribution to evolutionary biology was NOT the theory of evolution which
proposed by others which some had ideas about adaption which mostly turn out to be wrong -
e.g. Lamarck )
o Darwin proposed the MECHANISM of evolution that could also explain adaption
= theory of evolution by natural selection in On the Origin of Species by Means
of Natural Selection,1859
Darwin is consider the parent of evolutionary theory because:
1. Provided evidence that evolution had occurred
2. Proposed natural selection
a. mechanism of evolution which could explain adaption
3. Provided evidence that evolution would occur by natural selection
a. wide variety of different fields put it together as strong case
Evolution as proposed by Charles Darwin:
all species descended from one or few original species he called it Descent with
modification (Darwin’s definition of evolution)
o emphasising the relatedness there is descent through some sort of family lineage
and modification that organism can adapt over the process of generation to their
his idea was that there were small changes w/in the populations from generation to generation
can accumulate over long periods of time (have large difference b/w groups of organism) and
lead to the origin of new species
key mechanism natural selection (not supernatural intervention)
Evolution by Natural Selection
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