"The Great Chain of Being." or

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• "The Great Chain of Being." or
• "Scala Naturae."
• All species could be placed on a ladder from
  bottom (worms) to top (guess who?)
• Species were stable no change called
• Doctrine of fixed species

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James Ussher (15811656) was

• Ussher is perhaps most famous for having dated
  the start of the creation to the evening before
  23rd October, 4004 B.C.
• Using the bible as his source of dating

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Jean-Baptiste Lamarck (1744-1829)

• "Do we not therefore perceive that by the action
  of the laws of organization . . . nature has in
  favorable times, places, and climates multiplied
  her first germs of animality, given place to
  developments of their organizations, . . . and
  increased and diversified their organs?

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• Theory of Acquired Characteristics
• the concept, popularized by Lamarck, that traits
  gained during a lifetime can then be passed on to
  the next generation by genetic means. Generally
  this theory has not been given recognition but
  in terms of epigenetics it begins to seem
  possible.

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Theory of Use and disuseLamarck

• Lamarck thought that giraffes evolved their long
  necks by each generation stretching further to
  get leaves in trees and that this change in body
  shape was then inherited. 

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Thomas Malthus (1766-1834)

• In nature, plants and animals produce far more
  offspring than can survive, and that Man too is
  capable of overproducing if left unchecked.
• Darwin read his papers while on his voyage

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Georges Cuvier (1769-1832) catastrophism

• Almost single-handedly, he founded vertebrate
  paleontology as a scientific discipline and
  created the comparative method of organismal
  biology, an incredibly powerful tool. It was
  Cuvier who firmly established the fact of the
  extinction of past lifeforms.

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Charles Lyell (1797-1875) gentleman geologist

• The kinds of causes which affected the earth in
  the past must be assumed to have been exactly
  those we see in operation today
• In other words the world is old.

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This ends the pre Darwinian

• Review who these men are Timeline of
  Evolutionary Thought
• Charles Darwin, Alfred Russel Wallace, and Gregor
  Mendel laid the foundations of modern
  evolutionary theory.

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Gregor Mendel (1822-1884)

• We already know his contributions as the father
  of the study of genetics. Note he lived at the
  time of Darwin but Darwin had failed to read his
  papers thus he did not have this basis to write
  about in his work

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• So lets go back to the very beginning and see if
  we can see what Darwin saw in the fossils left
  behind and the clues in the living species now?
• Evolution Change
• Video of time line.

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And so they began

• London, June 30th, 1858.
• MY DEAR SIR,The accompanying papers, which we
  have the honour of communicating to the Linnean
  Society, and which all related to the same
  subject, viz. the Laws which affect the
  Production of Varieties, Races, and Species,
  contain the results of the investigations of two
  indefatigable naturalists, Mr. Charles Darwin and
  Mr. Alfred Wallace.

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Darwin Wallace

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• Darwin video
• Evolution

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• Charles Darwin
• 1809 -1882
•   I have called this principle, by whicheach
  slight variation, if useful, is preserved, by
  the term Natural Selection. Charles Darwin
  from "The Origin of Species"

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• From 1831 to 1836 Darwin served as naturalist
  aboard the H.M.S. Beagle on a British science
  expedition around the world.

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Darwin's observations

• 1. Species have the ability to produce more
  offspring than is necessary to replace themselves
  (superfecundity)
• Influenced by Mathis

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• 2. There is a finite pool of resources that is
  smaller than necessary to allow all offspring to
  survive
• Consider the point that there are limited
  resources needed for survival. There is
  competition and a struggle for existence

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• 3. Natural populations are of constant size (over
  the long term)
• This means that many are born and few survive.
  Just enough to balance the population with the
  resources.

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• 4. Individuals within a species vary in many
  characteristics.
• Think in terms of advantage.
• In the environment if the individual has an
  advantage they will receive more of the finite
  resources. This in turn allows them to reach
  reproductive age.

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• 5. Much of that variation is heritable.
• Those genes which provided the advantage are
  now passed down to the offspring. This alters
  the genes in the gene pool causing change. The
  population is best suited for that environment.

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Darwin's inferences

• 1. Individuals compete (or otherwise struggle
  with each other) for limited resources

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• 2. Only some individuals survive to reproduce
• those that more successfully obtain
  resources are more successful

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• 3. Over many generations, a population will
  consist of the most successful kinds of
  individuals
• These ideas were radical and Darwin waited for a
  long time to publish his work.
• Evolution Library Darwin Reluctant Rebel

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• Changes in o genetic instructions change the
  proteins that are made. This may lead to a more
  fit protein for the environment.
• Teachers' Domain An Origin of Species
• Natural selection Evolution Library Evolution
  of Camouflage
• Evolution Library Evolution of the Eye

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• Watch this and thing about the advantage this
  mutation may provide.
• Teachers' Domain Double Immunity
• Watch this for a study which has documented
  evolution.
• Teachers' Domain Evolving Ideas How Does
  Evolution Really Work?

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• There are adaptations (allele combinations) which
  are successful and those which are a
  disadvantage. One of these is the Heterozygous
  Advantage.
• Teachers' Domain Sickle vs. Normal Cell

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• We have seen this video before.
• Read page 102 of workbook Heterozygous
  Advantage first.
• Learn the correct notation
• Teachers' Domain A Mutation Story
• ( balanced polymorphism)

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• Genetic variation leads to success. This leads to
  a change in the gene pool of the population.
• Look at page workbook page called Natural
  Selection.

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Stabilizing selection

• When selective pressures select against the two
  extremes of a trait, the population experiences
  stabilizing selection. For example, plant height
  might be acted on by stabilizing selection. A
  plant that is too short may not be able to
  compete with other plants for sunlight. However,
  extremely tall plants may be more susceptible to
  wind damage.

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Directional selection

• In directional selection, one extreme of the
  trait distribution experiences selection against
  it. Using the familiar example of giraffe necks,
  there was a selection pressure against short
  necks, since individuals with short necks could
  not reach as many leaves on which to feed. As a
  result, the distribution of neck length shifted
  to favor individuals with long necks.

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Disruptive Selection

• In disruptive selection, selection pressures act
  against individuals in the middle of the trait
  distribution. The result is a bimodal, or
  two-peaked, curve in which the two extremes of
  the curve create their own smaller curves.

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• eLearning ( go to right column and look for
  types of selections )

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Industrial Melanism/Transient Polymorphism

• The peppered moth.
• Two forms (morphs) the gray mottled form and the
  dark melanic form.
• Changes in relative numbers was hypothesized to
  be the result of selective predation by birds.
• High industrial pollution make the darker moth
  less likely to be seen.

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• Melanin gives color to moths
• Black is a mutation of the white form (morphs),
  it is dominant.
• With industrial pollution the black allele became
  favorable. Increase in population of the
  dominant allele.
• Clean air, return of lichen , increase in
  recessive allele.

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Darwins famous finches

• The Galapagos islands
• Evolution Library Search Results

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• Evolution - Quantitative genetics

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Those beaks

• How about that vampire finch? Video "Vampire
  Birds" of the Galapagos Islands

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Common ancestor / adaptive radiation
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• Galapagos finches

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Gene pools

• Natural selection will favor genes that are more
  suited to their environment and become more
  exclusive in the gene pool over time in such an
  environment. Different genes will become more
  exclusive when the environment changes, or the
  species migrate.

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homework

• Go to Evolution
• Go to student teacher and do student lesson 4

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Evolution in a Genetic Context

• 1. Population genetics studies the genetic
  variation in a population. 2. The gene pool is
  the total of all the alleles in a population,
  described in terms of gene frequencies.

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Genetic Mutations

• 1. Natural populations contain high levels of
  allele variations. Gene mutations provide new
  alleles, and therefore are the ultimate source of
  variation.   a. A gene mutation is an alteration
  in the DNA nucleotide sequence of an allele.
    b. Mutations may not immediately affect the
  phenotype.   c. Mutations can be beneficial,
  neutral, or harmful a seemingly harmful mutation

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Gene Flow

• 1. Gene flow moves alleles among populations by
  migration of breeding individuals. gene_flow
  (animation)
• 2. Gene flow can increase variation within a
  population by introducing novel alleles produced
  by mutation   in another population.  3.
  Continued gene flow decreases diversity among
  populations, causing gene pools to become
  similar. 4. Gene flow among populations can
  prevent speciation from occurring.

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Nonrandom Mating

• 1. Random mating involves individuals pairing by
  chance, not according to genotype or phenotype.
• 2. Nonrandom mating involves individuals
  inbreeding and assortive mating. 3. Inbreeding
  is mating between relatives to a greater extent
  than by chance.             a. Inbreeding
  decreases the proportion of heterozygotes.
              b. Inbreeding increases the
  proportions of both homozygous at all gene loci.
              c. In human populations, inbreeding
  increases the frequency of recessive
  abnormalities

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• 4. Assortative mating occurs when individuals
  mate with those that have the same phenotype.
              a. Assortative mating divides a
  population into two phenotypic classes with
  reduced gene exchange.             b.
  Homozygotes for gene loci that control a trait
  increase, and heterozygotes for these loci
  decrease. 5. Sexual selection occurs when males
  compete for the right to reproduce and the female
  selects.

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• Sexual selection is often powerful enough to
  produce features that are harmful to the
  individuals survival. For example, extravagant
  and colorful tail feathers or fins are likely to
  attract predators as well as interested members
  of the opposite sex.

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Population Size

• A population must be large enough that chance
  occurrences cannot significantly change allelic
  frequencies significantly.

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The Hardy-Weinberg Law

• The unifying concept of population genetics is
  the Hardy-Weinberg Law (named after the two
  scientists who simultaneously discovered the
  law). The law predicts how gene frequencies will
  be transmitted from generation to generation
  given a specific set of assumptions. Specifically

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The If and then of it all

• If an infinitely large, random mating population
  is free from outside evolutionaryforces (i.e.
  mutation, migration and natural selection),

• then the gene frequencies will not change over
  time and the frequencies in the next generation
  will be p2 for the AA genotype, 2pq for the Aa
  genotype and q2 for the aa genotype.

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Assumptions

• large population - to insure no sampling error
  from one generation to the next
• random mating - no assortive mating or mating by
  genotype
• no mutations - or mutational equilbriumeven new
  mutations have little effect on allele
  frequencies from one generation to the next
• no migration between populations
• no selection - all genotypes reproduce with equal
  success

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Basic Relations

• two alleles at a gene - A and a
• frequency of the A allele p
• frequency of the a allele q
• p q 1
• 1 - q p

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• Or in a video these conditions would look
  likehttp//zoology.okstate.edu/zoo_lrc/biol1114/tu
  torials/Flash/life4e_15-6-OSU.swf

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• Another example animation
• Animation Quizzes

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Demo problems

• How to do the Hardy Weinberg.
• Hardy-Weinberg Problems

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• Go to workbook pages 110- 111

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Founder effect workbook 115

• Founder
• Remember the Amish. A small population which
  moved into the Penn. area of North America. One
  of the founders carried a gene for polydactylism.
  This gene was isolated to this tight knit
  community and the result is seen in the progeny
  today

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Bottleneck page 116

• Sudden reductions in population size can also
  alter the resulting gene pools. Any environmental
  condition in which many individuals are killed
  and only a small number survive, creates a
  bottleneck effect.

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• Northern elephant seals have reduced genetic
  variation probably because of a population
  bottleneck humans inflicted on them in the 1890s.
  Hunting reduced their population size to as few
  as 20 individuals at the end of the 19th century.
  Their population has since rebounded to over
  30,000but their genes still carry the marks of
  this bottleneck they have much less genetic
  variation than a population of southern elephant
  seals that was not so intensely hunted.

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The Cheetah and Florida Panther

• About 10,000 years ago cheetah as a species lost
  99 of population, it is speculated it went down
  to one pregnant female. As a result of the
  population crash, and the subsequent inbreeding,
  a male cheetah has a sperm count that is 90
  percent lower than tigers' and lions'. On top of
  that, 75 percent of the sperm that IS produced is
  abnormal. If cheetahs were livestock, they would
  be classified as infertile.

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Florida Panther

• There are between 30 and 50 Florida Panthers left
  and they are so inbred that the cubs are starting
  to be born with heart defects.

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Genetic Drift

• Genetic Drift Simulation
• gene frequencies change randomly
• particularly prevalent in small populations.

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So what is it?

• A term that describes the random fluctuations in
  a gene pool over time. In large populations, the
  effects of genetic drift are negligible.
• In small populations like we just saw the impact
  can be big

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SPECIATION

• Species are groups of interbreeding natural
  populations that are reproductively isolated from
  other such groups.
• If something prevents gene flow, then you have a
  genetic divergence
• A genetic divergence is a buildup of differences
  between the allele pools of two or more
  populations.

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There are three models for differences in
speciation.

• Allopatric speciation - in the absence of gene
  flow between geographically separate populations,
  daughter species form gradually, by divergence.

• Chapter 4 Animations
• Go to allopatric animation.

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Ring Species

• Evolution Library Ring Species Salamanders

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• Sympatric speciation - daughter species arise
  from a group of individuals within an existing
  population. Found almost exclusively in plants

• speciation animations
• Good review of nondisjuction in plants. Need
  to watch all three animations

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Parapatric Speciation

• Daughter species arise due to reproductive
  isolation. Found most often in plants.

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• plants exhibiting different degrees of tolerance
  for heavy metals and living in the vicinity of
  mine tailings.

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• Species maintain their genetic distinctiveness
  through barriers to reproduction.
• Fall into two groups
• Prezygote isolation
• Postzygote isolation

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Behavioral isolation

• Evolution Library Isolating Mechanisms
  Lacewing Songs

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Microevolution

• Microevolution is used to refer to changes in the
  gene pool of a population over time which result
  in relatively small changes to the organisms in
  the population - changes which would not result
  in the newer organisms being considered as
  different species. Examples of such
  microevolutionary changes would include a change
  in a species' coloring or size.

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Macroevolution

• Is used to refer to changes in organisms which
  are significant enough that, over time, the newer
  organisms would be considered an entirely new
  species. In other words, the new organisms would
  be unable to mate with their ancestors, assuming
  we were able to bring them together.

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Patterns of evolution/Adaptive Radiation

• Sometimes many species evolve from a single
  ancestral species.
• Such an evolutionary pattern, in which many
  related species evolved from a single ancestral
  species, is called adaptive radiation. Usually
  occurs with new habitat, few competitors for
  resources.

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Patterns of evolution/divergent

• divergent evolution-occurs when a single group of
  organisms splits into two groups and each group
  evolves in increasingly different directions

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Hominid divergent evolution
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Parallel evolution

• parallel evolution-occurs when a group of
  organisms evolve into two distinct but similar
  lineages and continue to adapt in similar ways
  for a long period of time, often in response to a
  similar environment
• Note the mouthparts on these lamprey.

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lampreys
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• In the plant kingdom, the most familiar examples
  of parallel evolution are the forms of leaves,
  where very similar patterns have appeared again
  and again in separate genera and families.

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Convergent evolution

• Convergent evolution, when organisms that aren't
  closely related evolve similar traits as they
  both adapt to similar environments.

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Extinction

• Evolution Extinction
• 5 major extinctionsThe Five Worst Extinctions in
  Earth's History
• In The Wild SPOTLIGHT

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Punctuated Equilibrium ( rates of evolution)

• According to the theory of punctuated
  equilibrium, evolution proceeds relatively
  rapidly during speciation between speciation
  events the population remains relatively constant
  in a condition called stasis.
• Evolution - A-Z - Punctuated equilibrium

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Punctuated equilibrium(rates of evolution)

• evolution proceeds relatively rapidly during
  speciation between speciation events the
  population remains relatively constant in a
  condition called stasis.

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Gradualism

• Evolution has a fairly constant rate.
• New species arise by the gradual transformation
  of ancestral species.
• Evolution - A-Z - Phyletic gradualism The rate of
  evolution

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How about artificial life?

• Synthetic Theory of Evolution Micro and Macro
  Evolution