Download Theory of Evolution

Chapter 15
The Theory of Evolution
Objectives 15.1
• SUMMARIZE Darwin’s theory of
natural selection.
• EXPLAIN how the structural
and physiological adaptations
of organisms relate to natural
selection.
• DISTINGUISH among the types
of evidence of evolution.
Evolution
• Theory that explains all the changes
that have formed life on earth from its
beginning to common diversity
• Scientific theory NOT scientific fact
Based on a lot of info and experiments,
some of which is debatable and some
which is not
-Earth’s age:
a) 4.6 billion years old
b) Estimate originally based on only
studies of the earths crust.
c) Now also based on radioactive
dating.
Early Evolution Scientists
Lamarck (1800)- animals
changed over time by passing on
acquired traits
•Giraffes stretch necks to
reach higher in trees during
times of drought
•Necks get longer
•Children will acquire the long
necks
Early Evolution Scientists
Wallace (1840)- animals change by
passing genetic traits that are best suited
to the environment
•Giraffes have all different size necks
due to the variations in genes.
•During times of drought, the giraffe
with the longer necks will survive and
the giraffes with shorter necks will die
•Long neck giraffes will mate
•Long necked children will be produced
Wallace
Charles Darwin
• Began as a naturalist on
the HMS Beagle (an
English ship).
• Collected specimens over
his 5 year journey
• Small islands near the
equator
• Species live here that live
no where else in the
world.
(Continued Charles Darwin)
• Darwin (1840)theory the same as
Wallace, but Darwin
published the book
called, “The Origin
of Species”, so his
name is more
associated with the
current evolutionary
theory.
Darwin came up with 2 theories:
1) Decent with Modification: new
forms of organisms descend from old
forms but all species come from just a
few original species.
2).Modification by Natural
Selection: environment limits species by
affecting its birth and death rates. Best
suited to the environment will live and
reproduce.
How do species evolve?
•Species evolve due to natural
selection.
•Natural Selection- Process by
which organisms that are best
suited to the environment will
survive and reproduce passing
along the best traits for the
environment “survival of the fittest”
-Fittest means the organisms is best
suited to the environment will
survive and reproduce
Ex. 1) A type of deer are living
in a temperate environment
2) There are all different
thickness of furs on the deer. Some
have thinner coats and some have
thicker coats.
3) 2 separate
groups of deer are
formed due to
geographical isolation
(tidal wave,
earthquake, etc).
4) 1 of the groups
of deer migrates to a
colder are and the
other group moves to
a hot environment.
5) Deer with thicker
fur are more likely to
survive in a cold
environment, thin fur
deer will survive in a
hot environment.
6) Surviving deer will
mate and pass their
genes for their type of
fur.
Why did deer have
different thickness of fur
to begin with?
•Variations of a trait,
and this can be caused
by mutations, crossing
over, and genetic
recombination
•Variations are just
different alleles for the
same trait.
If a variation increases the
organisms chance to
survive and being able to
reproduce than it’s called
and adaptation.
Ex. -Opposable
thumbs in humans
-Wings on birds
- Elephant’s large
size and trunks
Traits that are good for
one organism aren’t
necessarily good for
another.
Ex.Wings on an
elephant No flight
Legs on a snakecan’t slither in
small places
Ball python- very muscular, unhinged jaw,
large fangs, skin color
Cock roach- exoskeleton, antenna, and
ability to climb
Millipede- a lot of legs, flexible, pieces of
exoskeleton
Tarantula- fangs, 8 legs, hair (sensing),
poison
Chameleon- Change
colors, opposable claws,
eyes, tongue
Scorpion- claws for
protection, venom, and
exoskeleton
Ring snake- colored for
protection
Bearded dragon- nails to
climb
Traits that are good for
one organism aren’t
necessarily good for
another.
Ex.Wings on an
elephant No flight
Legs on a snakecan’t slither in
small places
Evidence of Evolution
• 1) Fossils: remains or traces of an organism that lived in
the past
•
a) Preserved hard parts-bones
•
b) Preserved in amber- insects in tree sap
•
c) Preserved in ice- wooly mammoth and man
•
d) Preserved in tar
•
e) Petrifaction- turned to stone
•
f) Imprints-footprints
•
g) Molds and cast
•
h) Burrows
• -Most fossils are
formed when buried
in fine sediments
deposited by wind,
water, or volcanoes
• -Fossils being formed
with the exception,
not the norm. The
conditions have to be
PERFECT.
2. Comparative Anatomy
• -Study of
similarities
and
differences
among
living
organisms
• -Homologous structures- similar structure
but not necessarily similar function
indicates common ancestor but different
environments
•
Ex. Forelimbs: almost identical in a
variety of different animals
• -Analogous structures- structures similar in
appearance and function but no near
ancestor.
• Ex. Bird and insects have wings, evolved
in similar environment but are different
species.
• Vestigial structures- remnants of
structures that were functional in an
ancestral form.
•
Ex. The human body ahs a bout 100
vestigial structures: coccyx, the appendix,
wisdom teeth, the muscles that move your
ears and nose
•
Ex. Whales and pythons have hind leg
bones
3. Comparative
Embryology
• -Comparison of
the patterns of
development of
the embryos of
different types of
organisms
• -The longer the
organisms embryo
resemble each other
during development
the closer related they
are
• -Fish, birds, and
humans all have gill
slits, a two-chambered
heart, and similar traits
at one point during
embryo development
4. Comparative Biochemistry
• -comparison of the DNA and similar
protein molecules found in different
species
•
Ex. Man has 30,000 genes, 29, 550 are
identical to a chimpanzee
•
Ex. Hemoglobin (Blood Protein) is only
different by one amino acid between
gorillas and human, but is different by 67
between humans and frogs.
The Record of Life
• The sun with all those
planets revolving around
it and dependent on it,
can still ripen a bunch of
grapes as if it had
nothing else in the
universe to do… galelio