Download Microevolution focuses on studying genetic variation due to

Count the "F's" in the following text:
FINISHED FILES ARE THE RESULT OF YEARS OF SCIENTIFIC STUDY COMBINED WITH THE
EXPERIENCE OF YEARS...
How many?
3?
No…
…6.
Really.
The brain cannot process "OF".
Incredible or what ?
Anyone who counts all 6 "F's" on the first
go is a genius.
Three is normal, four is quite rare.
Understanding how earth, once devoid of
life, now teems with biodiversity is based
on two areas of study: microevolution and
macroevolution. In general, evolution is
the change in a population over time.
Microevolution
focuses on studying
genetic variation due
to recombination,
gene flow, genetic
drift, natural
selection, and
mutation at the
species and
subspecies level.
Macroevolution refers
to major evolutionary
changes over time, the
origin of new types of
organisms from
previously existing, but
different, ancestral
types. Examples of this
would be fish
descending from an
invertebrate animal, or
whales descending from
a land mammal.
Adaptation is brought about by cumulative
natural selection. Small changes, favored by
selection, can be the stepping-stone to further
changes. The summation of large numbers of
these changes is what we think of as evolution.
The Fossil Record
Fossils provide an actual record of Earth’s past
life-forms. Change over time (evolution) can be
seen in the fossil record. Fossilized species
found in older rocks are different from those
found in newer rocks.
Fossils of early
,
multicellular life-forms,
such as the crinoid, occur
in 800-million-year-old
rocks found in Indiana.
Fossils of the
pterodactyl, an extinct
reptile, occur in 140- to
210-million-year-old
rocks.
Whales are thought to have evolved from an
ancestral line of four-legged mammals
represented here by their fossils and
artistic reconstructions showing what scientists
think that they may have looked like.
Anatomical & Developmental
Comparisons of the anatomy of different types of organisms
often reveal basic similarities in body structures even though
the structure’s functions may differ between organisms.
sometimes bones are
present in an organism
but are reduced in
size and either have no
use or have a less important function
than they do in other, related organisms.
Such structures, which are considered to
be evidence of an organism’s evolutionary
past, are called vestigial structures. For
example, the hind limbs of whales are
vestigial structures.
Anatomical & Developmental
As different groups of vertebrates
evolved, their bodies evolved differently.
But similarities in bone structure can still
be seen, the forelimbs of the vertebrates
shown here are composed of the same
basic groups of bones. Such structures are
referred to as homologous structures
Homologous structures
are structures that have
a common structure
and function.
Humans
Penguins
cont.
Bats
Alligators
Anatomical & Developmental
cont.
However, as some
groups of organisms
evolved, their bodies
developed structures that while they
performed the same function for both
organisms, their structures were completely
different. Such structures are known as
analogous structures
Analogous structures are structures that have a
have a common function but a different structure.
Biological Molecules
If species have changed over time
as the fossil record indicates, then
the genes (DNA) that determine
the species’ characteristics should
also have changed.
These changes are due to mutations
and natural selection. As species
evolved, one change after another
should have become part of their
genetic instructions. Therefore,
more and more changes in the
organisms DNA should build up
over time.
By studying fossils,
scientists can learn
about the diversity of
life and about the
behavior of ancient
organisms.
About
95 percent
of the species that
have existed are
extinct they no longer
live on Earth.
Relative Dating
Its not just in Arkansas anymore!
• Scientists use a
variety of methods
to determine the
age of fossils.
One method is a
technique called
“relative dating”.
Relative Dating cont.
• If the rock layers have not been
disturbed,
the layers
at the
surface
must be
younger
than the
deeper
layers.
• Break into 6
equal lab groups
and read about
the Law of
Superposition.
• Paste a copy of the land
formations in your notebook
and work as a group to answer the
questions at the bottom of the handout.
3.
1.
2.
4.Suppose
Which
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fossils
you
oneisalso
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and
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and
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ages
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all layers
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formations?
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Since layer E lies beneath layer D,
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1. Do you think the pattern of change
the
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inshown
layers
age
and
D
by
and
layers
theC.
horse
D and
teeth
C are
layer
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2
may
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2. How would you test this hypothesis?
and
fossil
records.
supports this hypothesis? Why
the same
or why
age,
not?
B and A are likely the
eroded
They are
by older
wind than
or water
the fossils
or mayinhave
layers
same
age.
Layer
A
is
probably
the
(Yes,
you
see
afallen
change
from
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above
the
(studybecause
the teeth
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living
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study
D
andaway
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the
oftooth
otherto
herbivore
fossils
found with
fossil horses
B, which is the same age as A and
for similar patterns)
younger than C and B, which are
younger than D and C, which are
younger than E.
Relative Dating cont.
Oldest
• Using this principle,
scientists can
determine relative
age and the order
of appearance of
the species that
are preserved as
fossils in the
layers.
Youngest
• The fossils in the top layer must also be
younger than those in deeper layers.
Begin by
reading the
introduction
to the Where
The Hippos
Roam Lab
Activity.
Read the
Problem from
the bottom
half of page 2
and use the
data table at
the top of the
page to
complete the
grid on the
following page.
Complete the grid based on
the information you
gathered from page 2 of the
lab handout.
Answer the analysis
question usig complete
sentences