Evolution and Biodiversity

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Chapter 4

• Evolution and Biodiversity

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Earth The Just-Right, Adaptable Planet

• During the 3.7 billion years since life arose on
  Earth, the average surface temperature of the
  earth has remained within the range of 10-20oC

Figure 4-1
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The consistent temperature range has allowed life
to Evolve, Flourish and Diversify on Planet
EarthOur Home
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Evolution of Life On Earth
Chemical Evolution (1 billion years)
Biological Evolution (3.7 billion years)
Formation of the earths early crust
and atmosphere
Variety of multicellular organisms form, first in
the seas and later on land
Large organic molecules (biopolymers) form in
the seas
First protocells form in the seas
Single-cell prokaryotes form in the seas
Single-cell eukaryotes form in the seas
Small organic molecules form in the seas
Fig. 4-2, p. 84
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Stanley Millers ExperimentOr- How we figured
our how life evolved from non-living components
PLAY ANIMATION
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Stanley Millers Experiment

• Vial of Material from Original Experiments Found
  (youtube) 1.5 mins
• Bill Nye Explains Stanley Millers Experiments
• Creating the Potential for Life (united
  streaming) 8 mins
• Time Line -1953 Millers Experiments
• 1977 Undersea vent discovery

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Time Frame of Human Evolution

• Time Scales Demonstration- Ten Reams of paper.
  Each ream (500 sheets) represents 500 million
  years. The entire 10 reams is 5 billion years.
  This represents Geological Time

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Modern humans (Homo sapiens sapiens) appear about
2 seconds before midnight
Recorded human history begins about 1/4 second
before midnight
Age of mammals
Age of reptiles
Insects and amphibians invade the land
Origin of life (3.6-3.8 billion years ago)
First fossil record of animals
Plants begin invading land
Evolution and expansion of life
Fig. 4-3, p. 84
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• If the diagram of Evolution were a clock, at what
  time would Fish have evolved?
• What time are flowering plants present?
• What time do humans evolve?

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Animation Evolutionary Tree of Life
PLAY ANIMATION
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• Our knowledge about past life comes from fossils,
  chemical analysis, cores drilled out of buried
  ice, and DNA analysis

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NATURAL SELECTION

• Evolution by natural selection involves the
  change in a populations genetic makeup through
  successive generations
• Through either
• genetic variability
• Mutations random changes in DNA that can be
  inherited by offspring

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Natural Selection and Adaptation

• 3 conditions are necessary for evolution
• Genetic variability
• Traits must be heritable
• Trait must lead to differential reproduction

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Animation Stabilizing Selection
PLAY ANIMATION
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Animation Disruptive Selection
PLAY ANIMATION
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Directional Selection
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Moth Populations Directional Selection
PLAY ANIMATION
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Types of Natural Selection

• Stabilizing occurs when the most common
  phenotype is selected for.
• Disruptive occurs when changes favor individuals
  at both extremes of the distribution, individuals
  at the extremes contribute more offspring than
  those in the center, producing two peaks.
• Directional occurs when natural selection favors
  a single phenotype and therefore allele frequency
  continuously shifts in one direction.

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Wrap Up of Natural Selection TypesAdaptive Trait
Game
PLAY ANIMATION
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Limits on Adaptation through Natural Selection

• A populations ability to adapt to new
  environmental conditions through natural
  selection is limited by its gene pool and how
  fast it can reproduce.

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Coevolution

• Interacting species can engage in a back and
  forth genetic contest in which each gains a
  temporary genetic advantage over the other. This
  often happens between predators and prey species
• Example Toxic Newts

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Evolution and Geological Time

• Over the last billion years, the location of the
  continents has changed. This has led to the
  evolution of similar species on different
  continents

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225 million years ago
225 million years ago
135 million years ago
65 million years ago
Present
Fig. 4-5, p. 88
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Video Continental Drift
PLAY VIDEO
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• Changes in climate throughout the earths history
  have shifted where plants and animals can live

Figure 4-6
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• Asteroids and meteorites hitting the earth have
  wiped out large numbers of species and created
  evolutionary opportunities for Natural Selection
  of new species
• Ex KT Meteorite killed off dinosaurs and gave
  rise to the age of mammals

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• Every species in an ecosystem has a specific role
  or Niche
• Fundamental niche the potential range conditions
  and resources a species could theoretically use
• Realized niche to survive and avoid competition,
  a species usually occupies only part of its
  fundamental niche

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2 Species of Barnacles- 2 niche
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• In the previous diagram the two species of
  barnacles grow on different parts of the rocks.
  When the lighter coloured (Balanus sp.) were
  removed from the rocks the darker coloured
  (Chthamatus sp.) was able to move down onto the
  unoccupied surface. But when the Chthamatus sp.
  was removed from the upper areas of the rock
  Balanus sp. was not able to move up and occupy
  these upper areas, because Balanus sp. can't
  stand to be exposed to the air for a long time,
  which is the case with rocks close to the high
  tide mark. Balanus can only occupy the lower
  niche.

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Generalist and Specialist
Generalist species tolerate a wide range of
conditions.

• Specialist species can only tolerate a narrow
  range of conditions.

Figure 4-7
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Cockroaches Natures Ultimate Survivors

• 350 million years old
• 3,500 different species
• Ultimate generalist
• Can eat almost anything.
• Can live and breed almost anywhere.
• Can tolerate radiation.

Figure 4-A
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Specialized Feeding Niches

• Resource partitioning reduces competition and
  allows sharing of limited resources.

Figure 4-8
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Avocet sweeps bill through mud and surface water
in search of small crustaceans, insects, and
seeds
Ruddy turnstone searches under shells and
pebbles for small invertebrates
Herring gull is a tireless scavenger
Brown pelican dives for fish, which it locates
from the air
Dowitcher probes deeply into mud in search
of snails, marine worms, and small crustaceans
Black skimmer seizes small fish at water surface
Louisiana heron wades into water to seize small
fish
Piping plover feeds on insects and
tiny crustaceans on sandy beaches
Oystercatcher feeds on clams, mussels, and other
shellfish into which it pries its narrow beak
Flamingo feeds on minute organisms in mud
Scaup and other diving ducks feed on mollusks,
crustaceans,and aquatic vegetation
Knot (a sandpiper) picks up worms and small
crustaceans left by receding tide
(Birds not drawn to scale)
Fig. 4-8, pp. 90-91
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Video Frogs Galore
PLAY VIDEO

• From ABC News, Environmental Science in the
  Headlines, 2005 DVD.

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SPECIATION

• Speciation A new species can arise when member
  of a population become isolated for a long period
  of time

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Evolutionary Divergence

• Each of the finches evolved into a new species,
  from a common ancestor, to fill a niche

Figure 4-9
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Animation Speciation on an Archipelago
PLAY ANIMATION
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Animation Evolutionary Tree Diagrams
PLAY ANIMATION
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Geographic Isolation

• can lead to reproductive isolation, divergence
  of gene pools and speciation.

Figure 4-10
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Extinction

• Extinction occurs when the population cannot
  adapt to changing environmental conditions.

• The golden toad of Costa Ricas Monteverde cloud
  forest became extinct because of climate change.

Figure 4-11
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Species and families experiencing mass
extinction
Bar width represents relative number of living
species
Millions of years ago
Era
Period
Current extinction crisis caused by human
activities.
Extinction
Quaternary
Today
Cenozoic
Tertiary
Extinction
65
Cretaceous up to 80 of reptiles (dinosaurs)
Cretaceous
Mesozoic
Jurassic
Triassic 35 of animal families
Extinction
180
Triassic
Permian 90 of animal families
Extinction
250
Permian
Carboniferous
Extinction
345
Devonian 30 of animal families
Devonian
Paleozoic
Silurian
Ordovician
Extinction
Ordovician 50 of animal families
500
Cambrian
Fig. 4-12, p. 93
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GREATEST EXTINCTIONS THROUGHOUT HISTORY
Current Day
Jurassic
Cretaceous
Devonian
Permian
Ordovician
Terrestrial
Dinosaurs go extinct
Marine
Number of families
Millions of years ago
Fig. 4-13, p. 94
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Effects of Humans on Biodiversity

• The scientific consensus is that human activities
  are decreasing the earths biodiversity.

Figure 4-13
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GENETIC ENGINEERING

• We have used artificial selection to change the
  genetic characteristics of populations with
  similar genes through selective breeding.
• (Cows are an example of this)

• We have used genetic engineering to transfer
  genes from one species to another.

The mouse on the right has been engineered to be
obese.
Figure 4-15
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Genetic Engineering Genetically Modified
Organisms (GMO)
recombinant DNA genes from different organisms
are combined.
Figure 4-14
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Animation Transgenic Plants
PLAY ANIMATION

• From ABC News, Biology in the Headlines, 2005 DVD.

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Video Cloned Pooch
PLAY VIDEO

• From ABC News, Biology in the Headlines, 2005 DVD.

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How Did We Become Such a Powerful Species so
Quickly?

• We lack
• strength, speed, agility.
• weapons (claws, fangs), protection (shell).
• poor hearing and vision.
• We have thrived as a species because of our
• -opposable thumbs, ability to walk upright, and
  complex brains (problem solving).