ANTC17H3 Lecture Notes - Catastrophism, Mutation, Gradualism

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Published on 6 Jul 2012
School
Department
Course
Evolution: Descent with
modification
Key aspects of evolution
Variation already exists within
populations
-
Survival of the Fittest
(Competition for survival because
of lack of resources)
-
Natural selection *
-
Sexual Selection
-
Descent with modification (passed
on through generations)
-
Allele frequency =
population; mutation =
individual levels
Who does evolution act upon?
Population***
-
May be quite similar in
appearance or variable (ie.
Deer vs. dogs)
Shared behavioural traits
relating to social groups,
food preferences,
reproductive strategies
(may be same species but
do not mate) ,
differentiation
What is a species?
-
History, Mechanism, Processes
Waited to publish because of fear of
ostracizing
Nothing about humans, that was in the
Descent of Man
On the Origin of Species: 1859
-
Creation mythology usually involving a deity
Story of Genesis, literal understanding
Pre-Enlightenment beliefs on Origin of Species
-
1650 used geneologies in Bible to determine
age of the Earth
4004 BCE, 9am in the morning
Ussher 1581-1656
-
Catastrophism (George Cuvier 1769-1832)
Idea of huge violent events causing changes in
the geology of the earth
If Ussher's earth age was correct, how to explain
geology
-
Slow erosion and idea that the
Buffon 1749, Hutton 1788, Lyell 1873
Conclusion that the world was at least
100,000 years old
Actual age 4.5 billion years old; 14 billion
years for universe
Chalmer - Idea that Ussher was wrong, not the
Bible
Shift then to Uniformitarianism
-
Comparative Biology and the categorization of
species and their relations
7 Basic layers of taxon
Kingdom, Phylum, Class, Order, Family, Genus,
Species
Binomial Nomenclature
Used Homo Sapiens to identify humans,
thereby categorizing humans as animals
Carlos Linneus 1758
-
Acceptance of the Earth changing
Geology - Stratigraphy; as rock erodes it
deposits sediment, lower levels are
progressively older
Fossils of extinct animals
Question becomes not if they had changed
but how
End of Englightenment
-
Idea that you can adapt to the
environment (ie. Necks growing longer)
and then pass that along to future
generations
Problematic because you can't pass
along a trait that isn't genetic
Inheritance of acquired characteristics
Great Chain of Being
Progression towards perfection
Only really accurate point
Adaptation to environments
Lamark
-
Mechanism of Evolution: Natural Selection
Variation already exists which allows for
adaptation
Those who are already adapted have higher
reproductive success
Increases frequency of traits within the
species
Variation is random with not direction
If a population of geographically separated
and reproductively isolated the different
populations will be exposed to different
population pressures and may over time
become different species
Darwin and Wallace
-
Darwin's Finches
Beak shape related to diet
Studied relationship between available food
and beak size over generations
Individuals on the Island with larger beaks
were selected for because of their ability to
eat during a drought; frequency of occurrence
of this beak size increased
After the drought, those who had insect beaks
became more common
Grant and Grant 2002
-
Gregor Mendel 1822-1884
Bred pea plants, traits in offspring are not
passed solely by either parent, but are passed
on in small, independent packages from both
parents
Ratio of 3:1
Variation of the genes are called alleles
Genetics and Alleles
-
All genes are just as likely to be passed
on
Independent assortment
Laws of Mendelian Inheritances
-
Basic Genetics
Processes of Genetic Evolution
Only direct way to create
new alleles
a.
Radiation, Error in DNA
recombination
b.
Advantageous, deleterious,
or neutral
c.
Mutation
1.
Two different Levels: Fission
of two groups, stop
interbreeding over
generations, each group
develops new alleles;
continuation eventually can
lead to speciation
a.
b.
Genetic Drift
2.
Two different Demes of
breeding populations, with
some degree of natural
selection
a.
If they start to interbreed
again, than new genetic
information will be
introduced to the breeding
pool
b.
Gene Flow
3.
Theories of Speciation
Constant slow change over
time
a.
Darwin's approach
b.
Gradualism
1.
Neo-darwinism
a.
Most species have a status
quo
b.
Severe changes in drastic
climactic shifts
c.
Many species coming from
one selection event known
as adaptive radiation (ie.
Miocene Apes)
d.
Punctuated Equilibrium
2.
Primate Relationships
Difference between humans and other
primates: Bipedalism
-
Traits of Primates
Nails instead of claws
-
Opposable Thumbs
-
Stereoscopic vision
-
Primary sense = vision
-
Mostly arboreal
-
Specialized dentition
-
Large complex brain in relation to body
size
-
Complex social organisation
-
Infant dependency
-
Groups of Primates
Humans
-
Apes (Old World)
-
Old World Monkeys
-
New World Monkeys
-
Lemurs and Lorises and Tarsiers
-
Humans as Apes
Tailless
-
Y5 Cusp
-
2:1:2:3
-
Brain to body size ratio and large body
size
-
Classification Schemes
Phenetics: Linnean style, similarities
and differences
-
Vs.
Cladistics: Evolutionary branching or
shared derived traits
-
How are things related?
Homologies: trait shared by two or
more species through inheritance from
a common ancestor
-
Analogies: Trait shared by two or more
species that is similar in function but
unrelated evolutionarily; convergence
-
Example: Wing of bat and wing of
butterfly are analogous
-
Seminal Papers
First time study on origin of
homo sapiens through genetics
Female lineage (mtDNA)
Standard rate of mutation at
2-4% per million years
Africa as origin of Homo Sapiens,
around 200,000ya
Cann et al. 1987 "Eve"
-
mtDNA from Neanderthal
specimens
Compared DNA with data set
from Cann et al.
Noticed that DNA was outside
the rage of variation for Homo
Sapiens
Problematic because it's one
sample
Places divergence at 300-800 kya
No admixture
Krings et al. 1997
-
Evolution and Genetics
January-18-12
1:05 PM
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Document Summary

Survival of the fittest (competition for survival because of lack of resources) Allele frequency = population; mutation = individual levels. A group of organisms which can reproduce viable offspring which themselves are fertile. May be quite similar in appearance or variable (ie. deer vs. dogs) Geography may be confined to a specific area or may be expansive. Shared behavioural traits relating to social groups, food preferences, reproductive strategies (may be same species but do not mate) , differentiation. Large complex brain in relation to body size. Brain to body size ratio and large body size. Homologies: trait shared by two or more species through inheritance from a common ancestor. Analogies: trait shared by two or more species that is similar in function but unrelated evolutionarily; convergence. Example: wing of bat and wing of butterfly are analogous. First time study on origin of homo sapiens through genetics. Africa as origin of homo sapiens, around 200,000ya.

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