ANT101H5 Lecture Notes - Lecture 2: Cytosine, Guanine, Thymine

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6 Feb 2016
Lecture 2 - History of Evolutionary Theory and Background Biology
January 14, 2013
Hypothesis started in Arab and Greek areas, and then moved to England.
Lyell is the father of geology. He didn't create the ideas, but rather summarized and
revised them.
History of Evolutionary Theory
oA change in the genetic structure of a population from one generation to the next.
The term is also frequently used to refer to the appearance of a new species.
History: Necessary Background Developments
oExperimental science and hypothesis testing.
oUniformitarianism is the concept that processes that happen in the present (ex.
flooding, volcanic eruptions, everyday snow melt, etc.) can be used to explain
deposits from the past. Not catastrophism which states changes in the earth are due
to sudden violent random events.
oLyell observed that earth is millions of years old. At that time, everyone thought it
was only some thousands of years old. This way there is an explanation for the time
needed for development of new species (a group of organisms that reproduce with
each other to produce viable offspring), fossilization, geologic processes etc.
oLinnaeus created the first taxonomy classification system where humans were
included with groups of animals. This was a very radical idea at that time, because
humans were known as superior and were always acknowledged as separate. 'Homo
oRecognized the change within species over time (as opposed to fixity of species,
stating that all species came onto the earth as they appear now, which is the
argument by creative design).
oLamarck attempted to explain evolutionary processes, stressing the effects of
environmental change.
Darwin-Wallace: Evolution by Natural Selection
oLamarck coined the term biology, which is the study of living organisms with
evolutionary change as the central concept.
oLamarck said inheritance of acquired characteristics requires variation to arise when
it is needed. He thought an organism could acquire characteristics in its lifetime.
oDarwin-Wallace was the first to mention that evolutionary change happens by
natural selection, which states that evolution requires that variation already exists.
The theory of natural selection is a mechanism for evolution, explaining how it
could happen. States that differential reproductive success in individuals leads to
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changes in the population. Natural selection affects the individual, but the
evolutionary change happens to the population. (Page 30 - 31).
oAcquired characteristic cannot be inherited.
Summary of Mechanism of Evolutionary Change by Natural Selection
For natural selection to occur, the:
1. Trait must be inherited.
2. There must be a variation in the trait within the population.
3. Fitness (the ability to produce offspring) is a relative measure, since it
changes as the environment changes.
oEx. Galapagos finches, Darwin's theory. Page 32, figure 2.10. Birds that had big
beaks used if for getting hard seeds, while smaller beaks were used for fruits. The
population shifted during the drought years, where fruits died off which left only
hard shell food left. So the large beak birds survived and produced offspring who
also had big beaks. The relative percentage (frequency of alleles) of beak size
changed in the population, so evolution occurred.
oEx. Peppered moth in northern England. Page 31-32, figure 2.15. Before there was a
lot of white bark, so white winged butterflies survived because they were able to
hide from their predators. But in the industrial revolution, soot covered the trees and
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