Biology: Chapters 9 and 10

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Biology Chapters 9 and 10

• Evolution and Classification

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Living things show unity of pattern

• In structure (anatomy)
• In embryology
• Even in biochemistry!
• The more similarities we see, the more closely
  organisms are related in a evolutionary sense.

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Embryos show relationships
fish
reptile
bird (chicken)
mammal (human)
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Structural similarities

• Are called homologies
• The next slide shown homologous structures in a
  variety of vertebrates
• The arrows show how each front leg (forelimb)
  could have evolved from an early reptile.

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1
early reptile
2
3
4
5
1
2
3
pterosaur
4
1
chicken
2
3
1
2
bat
1
3
4
5
porpoise
2
4
5
3
penguin
2
3
1
2
human
3
4
5
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Human and Cobra
backbone
pelvic girdle
coccyx (bones where many other mammals have a
tail)
thighbone attached to pelvic girdle
small bone attached to pelvic girdle
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Similarities in skull structure
adult
proportions in infant
chimpanzee
adult
proportions in infant
human
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Comparative Biochemistry

• Kinds and numbers of biochemical traits that
  species share is a clue to how closely they are
  related
• Can compare DNA, RNA, or proteins
• More similarity means species are more closely
  related
• All organisms use the same genetic code

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Sequence Conservation

• Cytochrome c functions in cellular respiration
• Deficits in this vital protein would be lethal
• Long sequences are identical in wheat, yeast, and
  a primate

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Similar forelimbs, similar biochemistry
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The fossil record gives evidence of evolution

• Older fossils are found deeper in sediments
• Older fossils are simpler that more recent
  fossils
• Occasionally fossils are so well preserved that
  they can show body coverings

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DINOSAUR AND EXTINCT BIRD
Dromaeosaurus
Archaeopteryx
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The SPECIES is a natural evolutionary unit

• Organisms that are the same species usually look
  more or less alike
• Members of a species are reproductively isolated,
  because under natural conditions they will only
  mate with others of their species to produce
  fertile offspring

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Are these members of the same or different
species?

• Lion Tiger--gt Liger or Tigron ( only
  occurs in zoos)
• Horse donkey--gt mule (sterile)
• Usually, that is see page 224!
• spaniel poodle --gt mixed breed dog
• Bullfrog Leopard Frog --gt embryo which does not
  survive

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Review Darwins Theory of Natural Selection

• Organisms are born with variations, and these
  variations can be inherited
• There is a constant struggle to obtain needed
  resources more are born than can survive
• Organisms with favorable variations tend to live
  to reproduce more often than organisms with less
  favorable variations
• In time, these favorable variations (adaptations)
  become more common in the population
• What would happen if the environment changed?

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Artificial Selection or Selective Breeding

• Gave Darwin his idea about Natural Selection
• Definition humans breed organisms with specific
  desired traits together to produce pure
  breeding line with desirable characteristics
• See page 228 for examples of Artificial Selection
  in chickens

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Examples of Natural Selection 1

• MRSA Development of antibiotic resistance in
  bacteria is now a serious problem.
• Antibiotics kill most but not all of a bacterial
  population. (A few lucky bacteria have a mutation
  which gives them resistance to a low level of the
  antibiotic.)
• These lucky bacteria are not as vigorous as
  other bacteria unless

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Examples of Natural Selection 1

• Unless the bacterial population is exposed to
  antibiotics.
• Then, guess who will survive, especially if the
  infected person does not take all of their pills?
• What would happen to the bacterial population as
  a result?
• See illustration on page 230

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Examples of Natural Selection 2

• Imagine a population of moths, some dark and some
  light living in a forest.
• Imagine the trees are covered with light-colored
  lichens Which moths be better adapted?
• Now imagine that many coal-burning industries
  begin releasing sooty smoke into the forest, and
  the trees become covered with the black
  particles Which moths be better adapted?
• This actually happened in England during the
  industrial revolution, we have the insect
  collections as evidence.
• This is called Industrial Melanism See page 229

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Examples of Natural Selection 3

• Examine the next slide, which shows the
  distribution of a mutant gene which causes sickle
  cell anemia. Lets call the gene A
• aa (normal hemoglobin) tend to get malaria and
  die
• Aa (sickle cell trait) tend to be resistant to
  malaria
• AA (sickle cell anemia) tended in the past to die
  at a young age from sickle-cell disease

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Distribution of malaria cases in Africa, Asia,
and the Middle East in the 1920s
Frequency of people with the sickle-cell trait
less than 1 in 1,600
1 in 400-1,600
1 in 180-400
1 in 100-180
1 in 64-100
more than 1 in 64
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Examples of Natural Selection 3

• Explain why the gene for sickle-cell anemia would
  remain in the population, even if it was fatal to
  have the genotype AA.

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In order for a population to evolve

• The populations gene pool must change. This
  means the alleles in the population must change
  in one of 3 ways
• Either new alleles must be added
• Or alleles must be removed
• Or the proportion of alleles must change

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If one or more of the 5 following criteria are
present, alleles will be added, removed, or their
frequency will change

• Mutations
• Migration (gene flow)
• Natural Selection
• Genetic Drift (Chance variations in gene pool,
  more common in small populations)
• Selective mating (mating is not entirely random)

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phenotypes of original population
A seabird carries a few seeds, stuck to its
feathers, from the mainland to a remote oceanic
island.
phenotype of island population
An example of genetic drift
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How geographic isolation can lead to a new species
1
A few individuals of a species on the mainland
reach isolated island 1. A new habitat produced a
new species.
3
2
4
Later in time, a few individuals of the new
species colonize nearby island 2. In this new
habitat, speciation again occurs. Now there are
2 species!
1
2
Speciation may also follow colonization of
islands 3 and 4. And it may follow invasion of
island 1 by species 2.
1
3
2
4
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There are two models of speciation

• Gradualism proposed by Darwin suggests that
  species evolve slowly through time, as variations
  gradually accumulate
• Punctuation a newer model, suggests that
  speciation occurs more rapidly, in response to
  sudden changes in the environment. (Sudden could
  mean 10s of thousands of years!)

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Gradual Model

• Speciation model in which species emerge through
  many small morphological changes that accumulate
  over a long time period
• Fits well with evidence from certain lineages in
  fossil record

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Punctuation Model

• Speciation model in which most changes in
  morphology are compressed into brief period near
  onset of divergence
• Supported by fossil evidence in some lineages

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Evolutionary TreesGradualism Punctuated Punctua
ted
Figure 18.11Page 300
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Adaptive Radiation

• Burst of divergence
• Single lineage gives rise to many new species
• New species fill vacant niches (adaptive zones)
• Niche (adaptive zone) is way of life
• Often occurs after a mass extinction!

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Adaptive Radiation of mammals after the
extinction of the dinosaurs
Figure 18.12Page 301
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Evolutionary patterns1

• Parallel evolution When related species
  continue to evolve in similar ways becasuse they
  live in the same type of habitat.
• Examples ostrich and rhea, horse and zebra

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Evolutionary patterns2

• Convergent evolution when distantly related
  organisms come to resemble each other (at least
  superficially) because they live in similar
  habitats.
• Example Euphorbia and Cactus (p. 228), shark
  and dolphin.

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Evolutionary patterns3

• Coevolution when two unrelated species evolve
  so each is adapted to the other.
• Examples flowers and their pollinators, most
  mutualistic relationships.

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Taxonomy

• Field of biology concerned with identifying,
  naming, and classifying species
• Somewhat subjective
• Information about species can be interpreted
  differently

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Phylogeny

• The scientific study of evolutionary
  relationships among species
• Practical applications
• Allows interpretation of the fossil record
• Allows us to classify organisms based on their
  evolutionary relationships

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Binomial System

• Devised by Carl von Linne
• (aka Carolus Linnaeus)
• Each species has a two-part Latin name
• First part is generic
• Second part is specific name

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Examples of binomial nomenclature

• Homo sapiens (modern humans)
• Homo habilis (an extinct species of human)
• Gorilla gorilla (guess who?)
• Querqus rubrum (red oak)
• Querqus alba (white oak)
• Acer rubrum (red maple)
• QUESTIONS
• WHICH ORGANISMS ARE MOST CLOSELY RELATED?
• WHAT IS THE GENUS AND SPECIES NAME OF EACH?

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Higher Taxa

• Kingdom
• Phylum
• Class
• Order
• Family

• Inclusive groupings meant to reflect
  relationships among species

King Phillip Came Over For Good Soup
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Examples of Classification
corn
vanilla orchid
housefly
human
Plantae
Anthophyta
Monocotyledonae
Asparagales
Orchidaceae
Vanilla
V. planifolia
http//animaldiversity.ummz.umich.edu/site/index.h
tml
Figure 19.17Page 318
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Can you fill in the blanks?
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Five-Kingdom Scheme

• Proposed in 1969 by Robert Whittaker

Monera Protista Fungi Plantae Animalia
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5 kingdoms or 6?
ANIMALS
PLANTS
arthropods
chordates
FUNGI
flowering plants
conifers
annelids
roundworms
echinoderms
ginkgos
sac
club
mollusks
fungi
fungi
cycads
horsetails
rotifers
zygospore-
ferns
forming
flatworms
fungi
cnidarians
lycophytes
bryophytes
sponges
chlorophytes
chytrids
green algae
amoeboid
PROTISTANS
protozoans
(stramenopiles)
(alveolates)
red
brown algae
ciliates
algae
chrysophytes
sporozoans
oomycotes
?
dinoflagellates
crown of eukaryotes
euglenoids
(rapid divergences)
slime molds

kinetoplastids
parabasalids
(e.g., Trichomonas)
EUBACTERIA
spirochetes
diplomonads
ARCHAEBACTERIA
(e.g., Giardia)
extreme
Gram-positive bacteria
chlamydias
halophiles
methanogens
cyanobacteria
proteobacteria
extreme
thermophiles
molecular origin of life
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The 6 kingdoms

• Prokaryotes or Monera in our book
• Archaebacteria prokaryotic, most like the first
  life forms on earth, live in extreme environments
• Eubacteria prokaryotic, many are decomposers or
  pathogens

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The 6 kingdoms

• All of the remaining Kingdoms are Eukaryotes
• Protista mostly unicellular. Variable, some
  resemble plants, animals, or fungi. Some have
  characteristics of both animals AND plants.
  Groups are probably not closely related to each
  other.

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The 6 kingdoms

• Multicellular Eukaryotes Plants, Animals, and
  Fungi
• Plants Photosynthetic autotrophs, cells walls
  made of cellulose, store food as starch. Sexual
  reproduction.
• Fungi absorptive heterotrophs, cells walls of
  chitin, either haploid or diploid, most are
  mulicellular, either sexual or asexual
  reproduction

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The 6 kingdoms

• Animals multicellular ingestive heterotrophs,
  embryos with a blastula stage, no cell walls,
  most have complex tissues and organs. Most
  reproduce sexually.

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Origins and history of Life on Earth

• 4,600 million years ago Earth forms
• 3,400 million years ago, first living cells
• (similar to Archaebacteria)
• 2,500 million years ago, evolution of
  photosynthesis. The O2 produced changes life on
  Earth forever! Ozone layer develops, O2 slowly
  accumulates in atmosphere
• 1,200 million years ago, evolution of cellular
  respiration. First eukaryotes appear
• 900 million years ago, first animals and plants
  appear.
• 350 million years ago, land plants and first
  amphibians appear (saw in American Museum)

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What was the atmosphere like on earth 4,000
million years ago?

• No oxygen, anaerobic
• Gases present were likely methane, ammonia,
  carbon dioxide, water vapor, hydrogen, and
  nitrogen
• The earth was bombarded by powerful uv radiation.
• There were strong electrical storms.
• Under those conditions, it appears life was
  inevitable!

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Millers Experiment
electrodes
to vacuum pump
spark discharge
CH4 NH3 H2O H2
gases
water out
condenser
water in
water droplets
water containing organic compounds
boiling water
liquid water in trap
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