Evolution and Biodiversity

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Chapter 4

• Evolution and Biodiversity

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Core Case StudyEarth The Just-Right, Adaptable
Planet

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

Figure 4-1
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ORIGINS OF LIFE

• 1 billion years of chemical change to form the
  first cells, followed by about 3.7 billion years
  of biological change.

Figure 4-2
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Biological Evolution

• This has led to the variety of species we find on
  the earth today.

Figure 4-2
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How Do We Know Which Organisms Lived in the Past?

• Our knowledge about past life comes from fossils,
  chemical analysis, cores drilled out of buried
  ice, and DNA analysis.

Figure 4-4
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EVOLUTION, NATURAL SELECTION, AND ADAPTATION

• Biological evolution by natural selection
  involves the change in a populations genetic
  makeup through successive generations.
• genetic variability
• Mutations random changes in the structure or
  number of DNA molecules in a cell that can be
  inherited by offspring.

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Natural Selection and Adaptation Leaving More
Offspring With Beneficial Traits

• Three conditions are necessary for biological
  evolution
• Genetic variability, traits must be heritable,
  trait must lead to differential reproduction.
• An adaptive trait is any heritable trait that
  enables an organism to survive through natural
  selection and reproduce better under prevailing
  environmental conditions.

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Coevolution A Biological Arms Race

• 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.

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Hybridization and Gene Swapping other Ways to
Exchange Genes

• New species can arise through hybridization.
• Occurs when individuals to two distinct species
  crossbreed to produce an fertile offspring.
• Some species (mostly microorganisms) can exchange
  genes without sexual reproduction.
• Horizontal gene transfer

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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.
• Humans have a relatively slow generation time
  (decades) and output ( of young) versus some
  other species.

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Common Myths about Evolution through Natural
Selection

• Evolution through natural selection is about the
  most descendants.
• Organisms do not develop certain traits because
  they need them.
• There is no such thing as genetic perfection.

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GEOLOGIC PROCESSES, CLIMATE CHANGE, CATASTROPHES,
AND EVOLUTION

• The movement of solid (tectonic) plates making up
  the earths surface, volcanic eruptions, and
  earthquakes can wipe out existing species and
  help form new ones.
• The locations of continents and oceanic basins
  influence climate.
• The movement of continents have allowed species
  to move.

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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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Climate Change and Natural Selection

• Changes in climate throughout the earths history
  have shifted where plants and animals can live.

Figure 4-6
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Catastrophes and Natural Selection

• Asteroids and meteorites hitting the earth and
  upheavals of the earth from geologic processes
  have wiped out large numbers of species and
  created evolutionary opportunities by natural
  selection of new species.

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ECOLOGICAL NICHES AND ADAPTATION

• Each species in an ecosystem has a specific role
  or way of life.
• Fundamental niche the full potential range of
  physical, chemical, and biological 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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Generalist and Specialist Species Broad and
Narrow Niches

• 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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SPOTLIGHTCockroaches Natures Ultimate Survivors

• 350 million years old
• 3,500 different species
• Ultimate generalist
• Can eat almost anything.
• Can live and breed almost anywhere.
• Can withstand massive 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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Evolutionary Divergence

• Each species has a beak specialized to take
  advantage of certain types of food resource.

Figure 4-9
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SPECIATION, EXTINCTION, AND BIODIVERSITY

• Speciation A new species can arise when member
  of a population become isolated for a long period
  of time.
• Genetic makeup changes, preventing them from
  producing fertile offspring with the original
  population if reunited.

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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 Lights Out

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

• The golden toad of Costa Ricas Monteverde cloud
  forest has become extinct because of changes in
  climate.

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. Many species are expected to become
extinct within the next 50100 years.
Extinction
Quaternary
Today
Cenozoic
Tertiary
Extinction
65
Cretaceous up to 80 of ruling reptiles
(dinosaurs) many marine species including
many foraminiferans and mollusks.
Cretaceous
Mesozoic
Jurassic
Triassic 35 of animal families, including many
reptiles and marine mollusks.
Extinction
180
Triassic
Permian 90 of animal families, including over
95 of marine species many trees, amphibians,
most bryozoans and brachiopods, all trilobites.
Extinction
250
Permian
Carboniferous
Extinction
345
Devonian 30 of animal families, including
agnathan and placoderm fishes and many trilobites.
Devonian
Paleozoic
Silurian
Ordovician
Extinction
Ordovician 50 of animal families, including
many trilobites.
500
Cambrian
Fig. 4-12, p. 93
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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 AND THE FUTURE OF EVOLUTION

• We have used artificial selection to change the
  genetic characteristics of populations with
  similar genes through selective breeding.

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

Figure 4-15
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Genetic Engineering Genetically Modified
Organisms (GMO)

• GMOs use recombinant DNA
• genes or portions of genes from different
  organisms.

Figure 4-14
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How Would You Vote?

• To conduct an instant in-class survey using a
  classroom response system, access JoinIn Clicker
  Content from the PowerLecture main menu for
  Living In the Environment.
• Should we legalize the production of human clones
  if a reasonably safe technology for doing so
  becomes available?
• a. No. Human cloning will lead to widespread
  human rights abuses and further overpopulation.
• b. Yes. People would benefit with longer and
  healthier lives.

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THE FUTURE OF EVOLUTION

• Biologists are learning to rebuild organisms from
  their cell components and to clone organisms.
• Cloning has lead to high miscarriage rates, rapid
  aging, organ defects.
• Genetic engineering can help improve human
  condition, but results are not always
  predictable.
• Do not know where the new gene will be located in
  the DNA molecules structure and how that will
  affect the organism.

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Controversy Over Genetic Engineering

• There are a number of privacy, ethical, legal and
  environmental issues.
• Should genetic engineering and development be
  regulated?
• What are the long-term environmental consequences?

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Case StudyHow 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,
  complex brains (problem solving).