Download Darwin and Evolution - Ms. Oldendorf`s AP Biology

Darwin and Evolution
Mrs. Oldendorf, AP Biology
The Pre-Darwinian view:
 The Earth is YOUNG! (~7,000 years old… according to
the Bible…)
 Each species was specially created and did not
change over time
 Variations are imperfections
 All observations are made to uphold the prevailing
worldview.
Darwin’s ideas were part of a larger
change already underway…
 There were other contributors!...
Carolus Linnaeus (1707-1780)
Taxonomy (science of classifying organisms)
Developed a binomial nomenclature (Homo
sapiens)
Two part names for each species
He believed in special creation and fixity of species
Georges LeClerc and
Georges Cuvier
 LeClerc – hinted towards some sort of a descent with
modification and influence of the environment on
species
 Cuvier – founded paleontology
 Extinctions  Catastrophism  the idea that catastrophic
extinctions occurred and repopulation followed by surviving
species
Lyell and Malthus
Lyell – wrote Principles of Geology – said Earth
was VERY OLD!
Malthus – wrote about how populations would
like to grow forever, but don’t … due to…
LIMITED RESOURCES!
Jean-Baptiste Lamarck
The idea of Acquired Characteristics
Involves descent with modification
Inheritance of Acquired Characteristics –
organisms became adapted to their
environment during their lifetime and pass
these adaptations to their offspring
Darwin’s Theory of Evolution…
what did he base it on!?
 HMS Beagle voyage
 Built on other scientists’ ideas
Darwin’s evidence
Geology and Fossils
-
Lyell's book, Principles of Geology, popularized the idea of Uniformitarianism –
the concept that "the present is the key to the past" and is functioning at the
same rates
-
Fossils of huge sloths and armadillo-like animals suggested modern forms were
descended from extinct forms with change over time; therefore species were
not fixed. (glyptodont, mylodon)
Biogeography
Geographical distribution of plants and animals
The Galapagos Islands
 Weird and unique species – tortoises, marine iguanas,
penguins in hot climate
 Each island had a variation of the tortoise  their necks
correlated with the different vegetation present
Darwin’s Finches
-
Finches on the Galápagos resembled a mainland finch but there were more
types.
- Galápagos finch species varied by nesting site, beak size, and eating habits.
- One unusual finch used a twig or thorn to pry out insects, a job normally
done by (missing) woodpeckers
The variation in finches posed questions to Darwin: did they descend from one
mainland ancestor or did islands allow isolated populations to evolve
independently, and could present-day species have resulted from changes
occurring in each isolated population?
So Darwin went home after
his voyage, and not until 20
YEARS LATER…
Published his book on Natural Selection
But he was only prompted to do so after he
got a letter from another naturalist asking for
his thoughts on his theory … the SAME
theory…
So UH-OH!! Better hurry up and publish!!
Sorry Sir Alfred Wallace…
(1859)
How Natural Selection and
Adaptation Works…
(What did Darwin say in his book)
Fitness = a measure of an organism’s
reproductive success
Consequences of Natural Selection:
1. An increasing proportion of individuals in SUCCEEDING
GENERATIONS will have the adaptive traits
2. The result is a POPULATION
LOCAL ENVIRONMENT
ADAPTED TO ITS
Natural Selection does not GIVE organisms
what they need, but allows organisms certain
organisms to survive and reproduce based on
what they HAVE (which is random)
NATURAL SELECTION ACTS
UPON INDIVIDUALS,
BUT CHANGES
POPULATIONS
Extinction
Occurs when previous
adaptations are no longer
suitable for the present
environment
Evolution in 4 Basic Steps:
1. Heritable Variation Exists
2. More individuals are produced than will survive
3. Some individuals have traits (adaptations) that help
them to survive and REPRODUCE
4. Survivors pass on those traits to their offspring (which
increases the number that have the trait).
 RESULTS: A POPULATION ADAPTED TO ITS ENVIRONMENT
Examples
Artificial Selection
 Just like natural selection, but the HUMANS select the
traits that “survive and prosper”
 Dog breeds, vegetables and foods and grains, cows,
horses, greyhounds, etc..
Pesticide Resistance (and Antibiotic
Resistance)
 Nature will find a way!
 Pesticide spraying kills all of the “bugs” that aren’t resistant
 Natural variation exists so that there are some that are resistant
 Those that survive reproduce and pass on their resistant traits
 And resistance increases!!
 Works the same for antibiotic resistance and anti-viral
resistance
Misconceptions on Evolution Video
 WATCH ME! CLICK ON ME!
Macroevolution vs.
Microevolution
 Macro – takes a very long time
and results in profound changes
in the species
 Micro – refers to minor changes
that can occur within a species in
a relatively short period of time,
 like a change in coloration within a
fish population.
Ancestry of Life…
A conclusion from Natural Selection?!
If we accept that life
evolves, logic
suggests that all life
shares a common
ancestor.
 This is supported by all of
the evidence we have
found.