Zoology – ORGANIC EVOLUTION
A. Pre-Darwinian
Evolutionary Ideas
1. Before the
18th century, speculation on
origin of species was not
scientific.
2. _________________________________
portrayed a constant
world after a creation event.
3. Early Greek
philosophers considered some ideas of evolutionary
change.
a. _____________________
were recognized as former life
destroyed by _________________________________.
c. Lacking a full
evolutionary concept, the idea faded before
the rise of _____________________.
4. Biblical
account of creation became a tenet of faith.
a. Evolutionary
views were heretical.
b. __________________________________________
calculated _____________________ as
date of life’s
creation.
5. French biologist Jean Baptiste de _____________________
offered first complete explanation
in _____________________.
a. He
convincingly argued that fossils were remains of
_____________________
animals.
b. Lamarck’s mechanism was inheritance of ___________
_____________________.
c. He explained
long necks of giraffes to stretching efforts of
ancestral giraffes.
d. Lamarck’s
concept is ____________________________;
individuals transform their own traits
to evolve.
e. In contrast,
or due to differential
survival among offspring.
7. Geologist
Sir Charles _____________________ established the
principle of _____________________.
a. Uniformitarianism consists of two important principles:
1) Laws of physics and
chemistry remain the same
throughout earth’s history.
2) Past geological events
occurred by natural
processes similar to those observed
today.
b. Natural forces acting
over long periods could explain
formation of fossil-bearing rocks.
c. Earth’s age
must be measured in
_____________________
of years.
1)
It is now accepted that earth is
_____________________ years old.
2)
Life has existed on earth for more than 3.5 billion
years.
d. Geological changes are
natural and without direction; both
concepts underpinned
B. Darwin’s Great Voyage
of Discovery (_____________________)
1. In 1831,
Charles Darwin (almost 23) sailed aboard the small
survey ship _____________________.
2.
a.
_____________________
and adjacent regions.
b. He unearthed long
extinct fossils and associated fossils of
South and
c. He saw
fossil seashells embedded in the
13,000 feet altitude.
d. Observing earthquakes
and severe erosion confirmed his
views of geological ages.
3. The __________________________________________
provided unique observations.
a. These
volcanic islands are on the equator 600 miles west
of
_____________________.
b. Each island
varied in tortoises, iguanas, mockingbirds and
ground finches.
c. The islands
had similar climate but varied vegetation.
d. Island species therefore
originated from
and were modified under the
varying conditions of different
islands.
4.
_____________________.
a. In 1838,
R. _____________________.
b. Having
studied artificial selection, a “struggle for
existence” because of overpopulation gave him a
mechanism for evolution of wild species by natural
selection.
c. In 1858, he
received a manuscript from a young naturalist,
__________________________________________,
summarizing the main points of natural selection.
d. Geologist Lyell and botanist Hooker persuaded
publish a paper jointly with
Wallace’s paper.
e.
in
1859: ________________________________________
_______________________________________________.
f. 1250 copies
sold of first printing in one day.
SHOW THE GREAT BOOKS SERIES: THE ORIGIN OF SPECIES
II. Darwin’s Theory – Evolution Occurs by _____________________________
A. Natural selection gives
a natural explanation for origins of adaptation.
B. Darwin’s theory of
natural selection consists of four observations and
three conclusions.
1. Observation 1: _____________________________________
_____________________________________________________.
a) If all
individuals produced survived, populations would
explode exponentially.
b)
produce 19 million offspring in
750 years. This is a SLOW
breeding species!
1) Elephant females breed at the earliest at 9
years,
and bear one calf every four
years until age fifty
optimally. It would take a female 40 years to bear 10
calves.
2. Observation 2: _____________________________________
_____________________________________________________
_____________________________________________________
_____________________________________________________.
a) Conclusion
1: The struggle for food, shelter,
and space
becomes increasingly severe with overpopulation. There is
competition for __________________________________
______________________________________________.
1)
In each generation, many individuals must die
young, fail
to reproduce, produce few offspring, or
produce
less-fit offspring that fail to survive &
reproduce in
their turn.
2) Survivors
represent only a small part of those
produced each generation.
3. Observation 3: _____________________________________
__________________________________________. Individual
members of a population differ from one another in their ability to
obtain resources, withstand environmental extremes, escape
predators, etc.
a)
Conclusion 2: The most well-adapted (the “fittest”)
individuals
in one generation will usually leave the most
offspring. This is _________________________________:
the process
by which the environment selects for those
individuals
whose traits best adapt them to that particular
environment.
4. Observation
4: _____________________________________
_____________________________________________________
_____________________________________________________.
a)
offspring.
b) Gregor
Mendel’s mechanisms of heredity were applied to
evolution many years later.
c) Conclusion
3: Over many generations,
differential, or
unequal, reproduction among
individuals with different
genetic makeup changes the overall
genetic composition of
the population. This generates new adaptations and new
species.
C. Natural selection can be
viewed as a two-part process: random and
non-random.
1. Production of variation among organisms is
random; mutation
does not generate traits preferentially.
2. The nonrandom component is the survival of
different traits.
SHOW BIOVIDEO:
THE EVIDENCE FOR EVOLUTION
III. Evidence for Evolution
A. The fossil record provides evidence of
evolutionary change over time.
1. The living
world is constantly changing in form and diversity.
Change in
animal life is directly seen in the 600-700 million-year
animal fossil history.
2. A fossil is
a remnant of past life.
a. Insects in
amber and frozen mammoths are actual
remains.
b. Teeth and bones can
petrify or become infiltrated with
silica and other minerals.
c. Molds,
casts, impressions and fossil excrement are also
fossils.
3. Most organisms leave no
fossils; the record is always incomplete
and requires interpretation.
4. Interpreting
the Fossil Record
a. The fossil
record is biased because preservation is
selective.
b. Vertebrate
skeletons and invertebrates with shells provide
more records.
c. Soft-bodied animals
leave fossils only in exceptional
conditions such as the Burgess Shale.
d. Fossils occur in
stratified layers; new deposits are on top
of older material.
1) The law of stratigraphy dates oldest layers at the
bottom and youngest at the top.
e. “Index” or
“guide” fossils are “indicators” of specific
geological periods.
5. Radiometric
Dating
a. In the late
1940s, this dating method was developed that
determines age of rocks.
b. Radioactive
decay of naturally occurring elements is
independent of heat and pressure.
c.
Potassium-Argon Dating
1) Potassium-40
(40K) decays to argon-40 (40Ar) and
Calcium-40 (40Ca).
2) Half-life of
potassium-40 is 1.3 billion years; half of
remainder will be gone at end of next 1.3 billion years,
etc.
3) Calculating
the ratio of remaining potassium-40 to
amount originally there provides mathematically close
estimate of age of deposit.
6. Evolutionary
Trends - Fossil record allows observation of
evolutionary change over broad periods of time.
a. Animals
species arise and go extinct repeatedly.
b. Animal
species typically survive 1-10 million years; there
is
much variability.
c. Horse
Evolution Shows Clear Trend
1) From Eocene
to Recent periods, genera and
species of horses were replaced.
2) Earlier
horses had smaller sized and fewer grinding
teeth, and more toes.
3) Reduction in
toes and increase in size and
numbers of grinding teeth correlate with
environmental changes.
B. Common Descent –
descended from a common ancestor.
1. Geographic Animal
Distribution and continental drift
a. Large flightless birds exist only in
the southern
hemisphere
1) extant rhea
of South America & emu of
2) extinct
giant moa of
of
b. These birds are flightless, their
ancestor couldn’t have
swum the oceans to these
continents. The explanation is
that their ancestor
evolved on the southern continent of
Gondwanaland. (The northern continent was Laurasia.)
2. Comparative
anatomy
a. All plants and animals descending from
a common
ancestor is divergent evolution.
1)
Homologous structures –
structures that may
differ in
function but that have similar
anatomy due to
descent from a
common ancestor.
a) For example, vertebrate limbs show the
same
basic structures (one upper arm bone,
two
forelimb bones, wrist bones, and finger
bones)
modified for different functions
(swimming
in penguins & whales, flight in bats
& birds, running in dogs
& sheep, grasping in
humans
& shrews)
b)
for
common descent.
c) It is inconceivable that nearly the same
bone
arrangements could be ideal for such
different
functions, as would be expected if
each
animal were created separately. This is
exactly
what we would expect if birds &
mammal
forelimbs evolved from a common
ancestor.
2)
Vestigial structures –
structures that serve no
apparent purpose
a) For example, vampire bats have molar
teeth even though they live on a diet of blood &
therefore don’t chew their food.
b) Pelvic bones exist in whales and certain
snakes.
c) This is “evolutionary baggage”
d) The appendix is a vestigial structure in
humans
b. Through convergent evolution, natural selection
has
shaped unrelated organisms into similar forms in similar
environments.
1) Natural selection predicts that, given
similar
environmental demands, unrelated organisms might
independently evolve superficially similar structures.
2) Such outwardly similar body parts in
unrelated
organism, called analogous
structures, often have
completely different internal anatomy because they
are not derived from a common ancestor.
3) For example:
wings of flies & birds; also fat-
insulated, streamlined shapes of seals (mammals) &
penguins (birds)
C. Modern Biochemical & genetic analyses
reveal relatedness among
diverse
organisms
1. The amino acid sequences of proteins are
remarkably similar
across a huge spectrum of species.
2. The chromosomes of chimpanzees & humans
are extremely
similar, showing that these species are closely related.
D. Artificial selection demonstrates that
organisms may be modified by
controlled
breeding
1. In a few hundred to at most a few thousand
years, man has bred
radically different dog breeds, from
the wolf by selecting qualities that were found desirable
&
selectively breeding for them.
2. What man can do, cannot nature do by selecting
for those
individuals best adapted to that environment
E. Evolution by Natural Selection Occurs Today
1. We can literally see that evolution is
occurring around us today
2. Peppered moths of
3. 1990’s
as bait, rare mutation became widespread
4. Any pesticide, herbicide, or antibiotic &
resistance