EVOLUTION: THE UNIFYING THEME How Explain Biological Adaptations

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EVOLUTION THE UNIFYING THEMEHow Explain
Biological Adaptations?
What is an adaptation?
Any form of a trait that helps an individual
survive and reproduce under prevailing
environmental conditions. Outcome of natural
selection I have called this principle, by
which each slight variation, if useful, is
preserved, by the term Natural Selection.
Charles Darwin
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EVOLUTION THE UNIFYING THEMENatural Selection
Necessary and Sufficient Conditions?
Phenotypic variation
Heritability
Functional consequences
RECALL 5 FACTS AND 3 INFERENCES
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Biological AdaptationPandas Thumb
Giant Panda
Grizzly Bear
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ADAPTATION Tinkering the Origin of
Adaptations
Sutures in the skulls of young mammals have been
advanced as a beautiful adaptation for aiding
parturition, and no doubt they facilitate or may
be indispensable for this act .
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ADAPTATION Tinkering the Origin of
Adaptations
but as sutures occur in the skulls of young
birds and reptiles, which have only to escape
from a broken egg, we may infer that this
structure has arisen from the laws of growth, and
has been taken advantage of in the parturition of
the higher animals.
Reptile Skull
Bird Skull
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ADAPTATION Tinkering Evolution
If we look at the sting of the bee, as having
originally existed in the remote progenitor as
a boring and serrated instrument, like that
in so many members of the same great order, and
which has been modified but not perfected for
its present purpose, with the poison originally
adapted to cause galls subsequently intensified
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LIFE IS OPPORTUNISTICMaking the Most of What Is
Pandas Thumb
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EVOLUTION THE UNIFYING THEMENatural Selection
Necessary and Sufficient Conditions
Phenotypic variation Heritability Consequences
Evolution, largely by natural selection, creates
biodiversity, Connectedness among life forms,
and helps to explain the Origin and maintenance
of adaptive traits.
But Can we see evolution in action? Can it be
observed in the wild? Can it be measured in the
laboratory? Yes
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DARWINS FINCHES

What form of natural selection?
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EVOLUTION THE UNIFYING THEMENatural Selection
and Biomedical Research
Consider microbial diseases AIDS, West Nile
fever, malaria Nightmarish illnesses because
they are so dangerous to large numbers of people
and so difficult/expensive to treat. Why?
Capacity for quick change They pass from
wildlife or domestic animals into humans such as
the highly pathogenic avian influenza A.
Inherent variability allows them to find news
ways of evading and defeating human immune
systems.
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EVOLUTION THE UNIFYING THEMENatural Selection
and Biomedical Research
Consider Microbial Diseases
They pass from wildlife or domestic animals into
humans such as the highly pathogenic avian
influenza A.
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EVOLUTION THE UNIFYING THEMENatural Selection
and Biomedical Research
Consider Microbial Diseases
They pass from wildlife to domestic animals such
as the pathogenic West Nile virus.
Arbovirus Arthropod-borne virus Arthropod
Mosquito vector
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Role of migratory birds?
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Spread of West Nile Virus
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Spread of West Nile Virus
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EVOLUTION THE UNIFYING THEMENatural Selection
and Biomedical Research
Consider Microbial Diseases AIDS and malaria
Inherent variability allows them to find
news ways of evading and defeating human immune
systems. How so?

By natural selection they acquire resistance to
drugs that should kill them. They evolve.
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Natural Selection and Biomedical Research
HIV/AIDS

• HIV Retrovirus. Virus is a non-cellular
  infectious
• Agent that has 2 defining characteristics
• Protein coat wrapped around nucleic acid core
• Cannot reproduce itself.

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Natural Selection and Biomedical Research
Malaria
Vector Female Anopheles mosquito


Parasitic sporozoan protistan, Plasmodium
spp Affects 100 million people kills 2.7
million People annually.
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Natural Selection and Biomedical Research
Staphylococcus aureus
Penicillin available in 1943 was almost
miraculously effective in fighting
staphylococcus infections. First resistant
strains of S. aureus reported in
1947. Methicillin 1960s by 1980s resistant
strains widespread. Vanomycin next weapon
against staph, and first Vancomycin-resistant
strain emerged in 2002.


Multi-drug resistant Staphylococcus
Penicillin
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EVOLUTION THE UNIFYING THEMENatural Selection
Necessary and Sufficient Conditions?
Phenotypic variation ability to survive an
antibiotic varies among different individuals of
species
Heritability the enzyme that digests the
antibiotic is made by a mutated gene, and
offspring inherit the trait. Gene is present in
daughter cells.
Functional consequences bacteria that
decompose the antibiotic are likely to outlive
their peers.
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EVOLUTION THE UNIFYING THEMENatural Selection
Necessary and Sufficient

• Phenotypic variation
• Heritability
• Differences have consequences in terms of
  survival and reproduction.
• If so, traits with positive consequences are
  passed on to the next generation traits with
  negative consequences are less likely to appear
  in the next generation. Over time the
  characteristics of the individuals in the
  population change.

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LIFE CREATES WITH MISTAKES

• Mistakes? Mutations
• What is a mutation?

• Why are mutations often regarded as abnormal
  (i.e., deviations from the norm)?
• Yet, mutation is the genesis of new genetic
  variation.
• See heritability
• See Text Chapter 13