Biological Evolution I




the unifying theory of biology

    • Without evolution ...

    biology does not make sense

Why not give equal time?

           It's only fair.

    1. Science is not democratic.

          - everyone does get a say.

          - but the best explaination is used.

          - alternative explantions are

          - but the best explaination is used.

          - How many times do you
             consider a explantion that
             does not work?

          - New  are explantions  are
            always considered.

          - but the best explaination is used.

       . . .  until  a better explation is proposed.

             • then the excitement of a
                scientific revolution!


             e.g. Plate Tectonics 1960's

Why not give equal time?

           It doesn't affect me.

1. Know your antibiotics.

    • Staph infections
Scientists have confirmed their suspicions that a strain of hospital bacteria Staphylococcus aureus acquired resistance to the powerful drug vancomycin from another species of bacteria also commonly found in hospitals

    • Tuberculocis




primitive corn

primitive corn




ecology and environmental change


    evolution = change

    biological evolution

       = changes in populations



    a group of interbreeding


               (must result in fertile offspring)




        a group of potentially

        interbreeding individuals.

        (result in fertile offspring)


Biological evolution

= changes in populations



Biologic evolution through

geologic time is a fact


(evidence is there for anyone to see)


Several theories have been

proposed to explain how

biological evolution works.

 Lamarkian evolution:

    • French Naturalist 1700's

    • inheritance of acquired

        "If a parent develops a feature,

        it will be passed onto its offspring."

    • giraffe neck example


    • weightlifter &
      butcher examples


    • Not how nature works

        • empirical evidence does not support

          Lamarkian evolution

    • Endorsed by Lysenco,
       Stalin's chief scientist

      (failure of Soviet agriculture)



Charles Darwin

1831 Voyage of the HMS Beagle

    Darwin made observations

    of natural distributions


  • Different animal groups in

    South vs. North America

  • Different fish species on

    each side of Panama

  • remote islands had
    no frogs or mammals

island chains had distinct
  species on each island.
    (Galapagos tortoises)

    • Birds with specialized beaks

    for feeding ...

    apparently have a
    common ancestor

Galapagos finches

Darwin suspected that

species could only originate

from other species


(Species are immutable)

"Origin of Species" 1859

(Darwin & Wallace)


Darwin's Theory of

Natural Selection

   (1) More individuals are

        produced than can survive.

    (2) Individuals vary

    (3) Individuals that have traits

        suited to their surroundings

        will survive and reproduce.

  (4a) If traits can be passed on
          to offspring (heritable),

  (4b) then the offspring of those
         organisms that survive ...

  (4c) will be more likely to

        survive  and  reproduce



  • More individuals produced
    than can survive

  • Individuals vary

  • Variation suited to surroundings
    allows for survival and

 • Offspring of surviving organisms
    (with heritable variation)
    will survive and reproduce


# 3 often called

"survival of the fittest"

but only
on a given day

Empirical Evidence

  (1) Domestication:

    Selective breeding of
    plants & animals

wolf ancestor 

 (2) Homology:

    Body structures with similar

    ancestry, but that now

    perform different functions

human fingers --- whale flippers
horse toes --- bat wings

 (3) Vestigial organs:

   Body parts that serve no
   apparent function,

   but were functional in
   an ancestor

Whale hips


 (4) The Fossil Record

    Principle of Fossil Succession
      of Smith

    Evidence is there for anyone
      to look.

    Apply your basic stratigraphic
      principles and ...

        see what you see


Post-Darwin Evidence
for Evolution

  (1) Embryology:

    Development of an individual

    embryo reflects the evolutionary

    history of its ancestral lineage

    Example = human gill slits

Human embryo

Starfish embryo

  (2) Artificial changes
       to natural populations

        industrial melanism
        in moths.

    (3) Genetic sequencing:

    Organisms that are more

    closely will share more genetic

    data in identical sequence

    Darwin did not have a

    mechanism for inheritance

    and variation.



Blended inheritance
Particulate inheritance.