Welcome Back to IB 150

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Welcome Back to IB 150
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Fishing Affects Albatross Aging
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Lecture 39

• Distinguish the fundamental kinds of questions
  you can ask about a biological system - proximate
  vs. evolutionary explanations
• Understand how the schedule of survival and
  reproduction over an organisms lifespan
  interacts with natural selection.
• Understand how extrinsic mortality influences the
  evolution of maximum lifespan
• Be able to explain why birds and bats live longer
  than terrestrial mammals

• Be able to interpret a plot of lifespan vs. body
  size
• Relate the evolutionary theory of aging to
  genetic diseases
• Know the genetic diseases mentioned progeria,
  macular degeneration, osteosclerosis, myopathy,
  cerebral arteriopathy
• Know what type I, II, and III survivorship curves
  are
• Know how human activities cause evolutionary
  changes by altering survivorship

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Lecture 40

• Know the six types of disease organisms
• Know the biological differences between them
• Understand that disease infection is the same as
  predation

• Understand the importance of transmission between
  hosts
• Understand the evolution of virulence
• Understand the factors that make infectious
  diseases important in the modern world

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A Controversial Speech
Top Scientist Advocates Mass Culling 90 Of
Human Population Fellow professors and
scientists applause and roar approval at elite's
twisted and genocidal population control agenda

• Eric Pianka - University of Texas
• Discussed the probability of a global pandemic in
  the near future that would wipe out 90 of the
  human race
• Accused of promoting eco-genocide
• Why might he think a global pandemic likely?

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What Are the Causes of Disease?

• Toxic substances - organic poisons, heavy metals,
  radiation, diet, etc.
• Living Organisms - feeding on us, directly or
  indirectly (through toxic byproducts) cause
  disease.

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Disease Organisms Are Consumers

• Pathogen Parasite Predators
• Converting our biomass into carbon, etc. for
  their use
• Difference - disease organisms only have a single
  host as a food source

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What Organisms Cause Disease?

• Viruses
• Bacteria
• Single-celled Eukaryotes
• Fungi
• Animals
• Prions

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Viruses

• Protein coat containing a strand of DNA or RNA
• Take over cells and cause them to make more
  viruses
• Origins of viruses are uncertain - rogue DNA?
• Viral diseases can be very difficult to treat -
  no metabolism to disrupt

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Bacteria

• Prokaryotes - single celled organisms with no
  nucleus, no organelles
• Enormously important cause of infectious diseases
  before the discovery of antibiotics
• Diseases are often caused by toxins produced by
  the bacteria

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Single - celled Eukaryotes

• Diverse group of complex organisms
• Internal pathogens like bacteria
• Often have complex life cycles with multiple
  hosts
• Hard to treat because of similar biochemistry to
  ourselves

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Fungi

• Multi-cellular organisms with filamentous bodies
  - absorb nutrients directly from the environment
• Many attack plants - rusts, blights, etc.
• A few live on animals - usually on exterior

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Animals

• Many animals live off other animals without
  eating them in the conventional manner
• Ectoparasites - feed on the surface (mosquitoes,
  ticks, leeches)
• Endoparasites - live inside the body - mostly
  flatworms or nematodes

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Prions

• Malformed Proteins
• Appear to cause normal proteins of the same form
  to take on the malformed state
• Rare - which is good because very difficult to
  treat and prevent

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Examples of Diseases

• Viruses - AIDS, polio, measles, SARS, West Nile,
  Influenza (including Bird Flu)
• Bacteria - Pneumonia, tuberculosis, cholera,
  bubonic plague, siphyllis, food poisoning, Lyme
  Disease, Anthrax
• Single-celled Eukaryotes - Giardia, Malaria,
  Sleeping Sickness

• Fungi - Athletes Foot, Ringworm
• Animals - Trichinosis, tapeworms,
  schistosomiasis, hookworms, pinworms
• Prions - Mad-Cow Disease, kuru

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Hosts and Transmission

• Disease organisms live in a host - only source of
  food.
• Evolutionary success - need to be able to move
  from one host to another (infection)
• Can happen directly or indirectly (through a
  vector)

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Host - Pathogen Co-evolution

• Species interactions - each exerts a selective
  force on the other.
• Can take the form of an arms race
• However the conflict is uneven
• Generation time, dependence on host
• How much should pathogen harm its host?

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Evolution of Virulence

• Virulence of a disease depends on both parasite
  and the host
• Host immune system - learns disease
• Parasite may evolve greater or lesser virulence

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Modification of Host to Increase Transmission

• Flukes - complex life cycles - multiple host
  species.
• Lancet fluke hosts snails, ants and sheep/cows
• Another fluke - snails, fish, and birds

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Toxoplasma

• Single-celled eukaryote - related to Malaria
• Infects cats, rats, and humans.
• Affects the response of rats to the odor of cat
  urine
• May affect human behavior as well

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Host Responses - Lizard Malaria

• Fever in endotherms (warm-blooded animals) is
  well known.
• Lizards with malaria bask longer to raise their
  body temperatures to higher levels

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Why Are Infectious Diseases A Pressing Concern?

• High Population Density
• Large Numbers of Domestic Animals
• Highly Mobile Human Populations
• Evolution of Drug Resistant Strains

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Past Pandemics

• Influenza during WWI
• Black Plague in Europe
• Decimation of Native American Populations
  following European arrival

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What kinds of diseases are likely to cause a
future pandemic?

• Ebola and related diseases - hard to contract and
  act too quickly
• Better candidates - Influenza or SARS - rapidly
  evolving and highly contagious

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Lecture 40

• Know the six types of disease organisms
• Know the biological differences between them
• Understand that disease infection is the same as
  predation

• Understand the importance of transmission between
  hosts
• Understand the evolution of virulence
• Understand the factors that make infectious
  diseases important in the modern world