Evolution

1
Evolution

• The quick view (which is opposite of how
  evolution works, so its kind of ironic eh?

2
Science vs. Religion

• What is science based on?
• Science is based on OBSERVABE evidence.
• What is religion based on?
• Religion is based on FAITH.
• By definition, faith is something that is not
  observable.
  
• Since they are 2 different fields, they arent
  really competing with each other
  

3
Religious Scientists?

• My religion consists of a humble admiration of
  the illimitable superior spirit who reveals
  himself in the slight details we are able to
  perceive with our frail and feeble mind.
• Albert Einstein (1879 - 1955)
• Science without religion is lame, religion
  without science is blind.
  
• Albert Einstein (1879 - 1955), "Science,
  Philosophy and Religion a Symposium", 1941
  
• Not only does God play dice, but... he sometimes
  throws them where they cannot be seen.
  
• Stephen Hawking

4
Evolution is a Theory

• To paraphrase Carl Sagan
• Creationists think that a theory is something
  that you made up while drunk one night.
  
• Theory Defined scientific principle to explain
  phenomena a set of facts, propositions, or
  principles analyzed in their relation to one
  another and used, especially in science, to
  explain phenomena
• MSN Encarta, http//encarta.msn.com/dictionary_/th
  eory.html
  
• Evolution is as much a theory as gravity is

5
A Final Quote

• In the immortal words, of The Gru
• Be opinionated, just not ignorant.

6
Dating

• Geologic Record
• Hypothetical library of all the known geological
  processes on Earth
  
• Determined through inference and dating methods
• Relative Dating (hee hee)
• Sediments are constantly being laid down.
• Over time, many layers form
• If a fossil is in a layer below a different
  fossil, it is older than that fossil

7
Dating

• Radiometric Dating
• Radioactive isotopes decay and form new isotopes
  - the rate this happens is called the isotopes
  half life
  
• Ex Potassium-40 decays to argon-40 and has a
  half life of 1.3 billion years
  
• Half a sample will decay to argon-40 in 1.3
  billion years
  
• So if there are equal amounts of potassium-40 and
  argon-40 in an area, the sample has been in place
  1.3 billion years
  
• Carbon 14 has a half life of only 70,000 years
  for more recent sample dating
  

8
Review

• How does the geologic record help us?
• What use is relative dating?
• What is radiometric dating?
• Why are different isotopes used in radiometric
  dating?
  

9
Charles Darwin

• English naturalist (scientist) 1809-1882
• 1831, Darwin took a job as a naturalist on the
  HMS Beagle
  
• Went on a 5-year scientific journey around the
  world
  
• He collected many biological and fossil
  speciments
  
• Combined with his previous and subsequent
  observations
  
• Published On the Origin of Species by Natural
  Selection in 1859
  
• These ideas are a basic unifying theme of biology
  today
  
• Without evolution, biology doesnt make as much
  sense

10
Selection

• Artificial selection
• Breeding organisms with specific traits in order
  to produce offspring with identical traits
  
• Natural selection
• A mechanism for change in populations
• Occurs when organisms with favorable traits
  survive, reproduce and pass their traits on to
  the next generation
  
• Organisms with these traits are said to be more
  fit
  
• Organisms without these traits are less likely to
  survive and reproduce

Darwin awards
11
Adaptations

• Adaptation
• Evolution of a structure, behavior, or internal
  process that enables an organism to respond to
  environmental factors and live to produce
  offspring
• Can also be the structure itself
• Structural adaptations take a long time
• Physiological adaptations can happen faster
• Bacteria strains develop resistances to
  antibiotics fairly quickly

12
Evidence for Evolution

• Fossil Record
• A hypothetical library of all the fossils
  collected around the world
  
• Fossils show changes throughout time
• 99 percent of all animals are now extinct
• Fossil record shows ancestors with similar
  characteristics

13
Evidence For Evolution

• Anatomy
• Homologous Structures are structural features
  with a common evolutionary origin
  
• Ex whale forelimb, crocodile forelimb, bird
  wing, human forelimb all look the same (p. 401)
  
• Can you think of other examples?
• Analogous Structures are body parts or organisms
  that do not have a common evolutionary origin but
  are similar in function
  
• Bird, bat and butterfly wings
• Show how organisms adapt to different ways of
  life and different conditions
  

14
Evidence for Evolution

• Vestigial Structures are body structures that no
  longer serve their original purpose, but was
  probably useful to an ancestor
  
• Ex human appendix, pelvic bone in baleen whale,
  tail in humans, some humans ability to wiggle
  their ears

15
Evidence for Evolution

• Embryology study of embryos of different
  species
  
• Many species share features in the young embryos
  
  
• Ex Mammals, reptiles, birds and fish all have a
  tail and pharyngeal pouches (develop into
  different respiratory systems)

16
Evidence for Evolution

• Biochemistry
• Nearly all organisms share DNA, ATP, and many
  enzymes among their biochemical molecules
  
• Organisms that share more similar enzymes, DNA
  sequences, etc. are more closely related

17
Review

• How did Darwin come up with his ides for natural
  selection?
  
• Some snakes have vestigial legs. Why is this
  considered evidence for evolution?
  
• Explain how adaptations such as camouflage help
  species survive.
  
• How do homologous structures provide evidence for
  evolution?
  
• Why did birds and bats both get wings?
• A parasite that lives in red blood cells causes
  the disease called malaria. In recent years, new
  strains of the parasite have appeared that are
  resistant to the drugs used to treat the disease.
  Explain how this could be an example of natural
  selection occurring.

18
Population Genetics

• Populations evolve, not individuals
• Natural selection acts on a range of phenotypes
  in a population
  
• Evolution is often defined as a change in the
  frequency of an allele in a population over time
  

19
Population Genetics

• All of the populations genes are in a
  theoretical gene pool
  
• The percentage a specific allele in the gene pool
  is called the allelic frequency
  
• A population in which the frequency of alleles
  remains relatively the same over generations is
  in genetic equilibrium
  
• Any change in this genetic equilibrium results in
  evolution

20
Hardy-Weinberg Principle

• How to Stop Evolution must meet all five
  requirements
  
• Population is so large, chance alone cannot
  change relative frequency (genetic drift doesnt
  occur)
  
• Mutations do not occur
• All genotypes have equal fitness (no natural
  selection)
  
• No organisms leave or enter a population
• Mating occurs at random

21
Mutations

• Mutation provides the raw material for evolution
  to act upon
  
• Poor mutations are selected against, good
  mutations are selected for
  
• Change the frequency of alleles
• Examples

22
Genetic Drift

• Genetic drift is the alteration of allelic
  frequencies by chance events
  
• Genetic drift can greatly affect small
  populations
  
• Ex The Amish community carries an allele that
  results in short arms and legs and extra fingers
  and toes (1/14 vs. 1/1000)

23
Natural Selection

• Still the most significant factor that causes
  changes in established gene pools
  
• Stabilizing Selection
• Natural selection that favors average individuals
  (on a normal curve) in a population
  
• Reduces variation in a population
• Ex With spiders, larger ones are found easier
  and eaten and small spiders cant find food as
  easily

24
Natural Selection

• Directional Selection
• Natural selection favors one of the extreme
  variations of a trait
  
• Can lead to rapid evolution
• Ex The food supply in an area is limited to hard
  nuts. Birds with short, strong beaks will
  survive
  
• Disruptive Selection
• Natural selection favors individuals with either
  extreme of a traits variation
  
• Can lead to evolution of 2 new species
• Ex A shelled, marine organism called a limpet
  has white, tan, and dark shells. The white and
  dark shells blend in on different colored rocks.
  Tan gets eaten.

25
Species

• A species is a group of organisms that look alike
  and can interbreed to produce fertile offspring
  in nature
  
• Speciation is the evolution of new species
• Occurs when members of similar populations no
  longer interbreed to produce fertile offspring
  within their natural environment

26
Causes of Speciation

• Physical barriers
• Volcanic eruptions, sea-level changes, new
  islands forming
  
• These prevent interbreeding
• Called geographic isolation
• Over time, may have to adapt to new types of
  environments

27
Causes of Speciation

• Reproductive Isolation
• Two types
• One occurs because of geographical reasons
  (migrate away)
  
• One occurs because of behavioral reasons
• Some mate in fall, some in spring

28
Polyploidy

• Individual with a multiple of a normal set of
  chromosomes
  
• How does this happen?
• New zygotes may not develop the same way as
  parents due to different number of chromosomes
  
• May result in speciation

29
Gradualism

• James Hutton Charles Lyell
• Theory that processes are moving at the same
  speed today as in the past
  
• Suggests that the Earth is very old 4.55
  billion years
  
• Also suggests that evolution occurs constantly,
  but slowly

30
Punctuated Equilibrium

• Remember first day of class?
• Niles Eldredge and Steven J. Gould
• Theory that speciation occurs relatively, in
  rapid bursts, with long periods of genetic
  equilibrium inbetween
  
• Might occur due to drastic environmental changes
  resulting in quick adaptations

31
Adaptive Radiation

• When an ancestral species evolves into an array
  of species to fit a number of diverse habitats
  
• Hawaiian Island honeycreepers
• Similar in body size and shape, but different
  sharply in color and beak shape
  
• Adapted to occupy different niches (whats a
  niche)

32
Divergent Evolution

• Adaptive radiation is a type of divergent
  evolution
  
• The pattern of evolution in which species that
  once were similar to an ancestral species
  diverge, or become increasingly distinct
  
• Galapagos Finches
• Similar changes for finches that ended up on
  different small islands

33
Convergent Evolution

• A pattern of evolution in which distantly related
  organisms evolve similar traits
  
• Occurs when different organisms occupy similar
  environments
  
• Adapt similar traits
• Example
• Organ pipe cactus in N. and S. American vs.
  Euphorbiaceae in African deserts both look very
  similar

34
Review

• Explain and illustrate why the evolution of
  resistance to antibiotics in bacteria is an
  example of directional natural selection.
  
• How can geographic isolation change a
  populations gene pool?
  
• Why is rapid evolutionary change more likely to
  occur in small populations?
  
• How do gradualism and punctuated equilibrium
  differ? How are they similar?
  
• Hummingbird moths are night-flying insects whose
  behavior and appearance are similar to those of
  hummingbirds. Explain how these two organisms
  demonstrate convergent evolution.
• What is divergent evolution? How does it compare
  to adaptive radiation?

35
Quick Tour of Ch 17

• Classification the grouping of objects or
  information based on similarities
  
• Taxonomy the branch of biology that groups and
  names organism based on studies of their
  different characteristics
  
• Aristotle was the first on record
• Classified organisms into two groups plants and
  animals, each with subgroups

36
Carolus Linnaeus

• Developed taxonomic system still used today
• Based on physical and structural similarities of
  organisms
  
• Grouped life into 7 taxa (groups) What are
  they?
  
• Kingdom, phylum, class, order, family, genus,
  species
  
• Five Kingdoms animals, plants, fungi, protists,
  monerans
  
• A six Kingdom system is becoming more and more
  common monera split into eubacteria and
  archaebacteria

37
Binomial Nomenclature

• All organisms have a two-word name
• Consists of their genus and their species
• Always italicized in type and underlined in
  writing
  
• Genus is capitalized, species is lower case
• Homo sapiens (human)
• Passer domesticus (sparrow)

38
Classification Key

• Sometimes called a dichotomous key
• Guide for identifying different species based
  on observable traits
  
• Useful for distinguishing between types of
  organisms

39
Modern Classification

• Generally based on evolutionary relationships vs.
  physical characteristics
  
• Used structural similarities, breeding behavior,
  geographical distribution, chromosome
  comparisons, biochemistry to figure out
  relationships

40
Phylogenetic Diagram

• Monerans evolved first (often broken up into
  archaebacteria and eubacteria)
  
• prokaryotes
• Protists then evolved
• Single celled eukaryotes
• Three general kinds of protists fungus like,
  animal like and plant like
  
• Fungi, Plants and Animals evolved from the types
  of protists

41
Review

• Why does your book use the classification system
  of six kingdoms instead of five?
  
• What two taxa does binomial nomenclature consist
  of?
  
• Why is classification hard to do?
• What are the 7 Linnaean taxa?
• How might you use taxonomic key to figure out the
  name of an organism?