Download Evidence of Evolution - Northwest ISD Moodle

Evidence of Evolution
• Anatomical Structures:
– Homologous & Analogous Structures
• Embryology & Molecular Similarities:
– Early Development
• Biogeography:
– Geographic Distribution of Living Things
• Fossil Record
• Phylogeny
ANATOMICAL STRUCTURES:
Homologous structure:
Similar structure and
position, but different
function
Courtesy of Prof. Ken Sytsma
http://evolution.berkeley.edu
Analogous structure:
Similar function, but
different origin
ANATOMICAL STRUCTURES:
Evidence for Evolution
• Vestigial Structures – structures
that serve no useful function in an
organism
• Examples: appendix, miniature legs,
arms
Embryology is the study of organisms in embryonic
stages.
The embryo is one of the earliest stages of growth and
development of both plants and animals.
The shared
features in the
embryos
suggests
evolution
from a distant
common
ancestor.
MOLECULAR: BIOCHEMISTRY
All living things have A,T,C,G in their DNA and use
the same codon chart to code for the same amino
acids.
Biogeography
“ the study of what organisms live
where on earth and why”
(from Humphries and Parenti, 1999)
• For fossils to form, organisms
usually have to be buried in mud,
sand, or clay soon after they die.
• Most fossils are found in sedimentary rocks.
rocks
form atfound
relatively
temperatures
and
pressures
• These
Fossils are
not usually
in otherlow
types
of rock because
of the
ways
thosemay
rocksprevent
form.
that
damage to the organism.
• Fossils are evidence of organisms that lived long ago
that are preserved in Earth’s rocks.
TYPES OF FOSSILS
Fossils Types
Formation
A trace fossil is any indirect evidence
Trace fossils
Casts
left by an animal and may include a
footprint, a trail, or a burrow.
When minerals in rocks fill a space
left by a decayed organism, they make
a replica, or cast, of the organism.
A mold forms when an organism is
Molds
Petrified
fossils
Amber-Preserved
or
frozen fossils
buried in sediment and then decays,
leaving an empty space.
Petrified-minerals sometimes penetrate
and replace the hard parts of an organism
At times, an entire organism was
quickly trapped in ice or tree sap that
hardened into amber.
• Relative dating
• LAW OF SUPERPOSITION:
• This method basically indicates that the fossils
found closer to the surface are younger and more
complex, and the fossils found in deeper strata are
more primitive (older).
• Relatively simple &
less time consuming
Compared to other
methods
• This method does not
give a specific age of
the fossil or rock.
• To find the specific ages of rocks, scientists use
absolute dating, also called Radiometric Dating or
Carbon Dating.
• In this type of dating scientists use radioactive
isotopes to determine the absolute age of objects.
As specific atoms decay they emit radiation and lose
electrons, which causes them to turn into a different
element.
So- these atoms change from one thing into something else
over time- and they do this at a constant rate.
• The half-life of a radioactive atom is the time it takes
for half of that atom in a sample to decay and turn into
another element.
Warm Up
• If the decay rate of Carbon-14 is 5730 years:
– How many years and half-lives will it take a
organism to have less than 1% of Carbon-14
remaining?
Warm Up
• If the decay rate of Carbon-14 is 5730 years:
– How many years and half-lives will it take a organism
to have less than 1% of Carbon-14 remaining?
– (7 half-lives) X 5730 years/half-life = 40,110 Years
– 7 half-lives:
100%/2= 50%/2= 25%/2= 12.5%/2= 6.25%/2=
3.125%/2= 1.6%/2= .78%
– How many years and half-lives will it take that same
organism to be a little over 6% remaining?
Overview: Investigating the Tree of Life
• Phylogeny is the evolutionary history of a species
or group of related species
• The discipline of systematics classifies organisms
and determines their evolutionary relationships
• Systematists use fossil, molecular, and genetic data
to infer evolutionary relationships
Constructing a CLADOGRAM:
What is Phylogenetics?
Phylogenetics is the study of evolutionary relationships
Example - relationship among species
primates
rodents
birds
crocodiles
marsupials
lizards
snakes
crocodiles
birds
lizards
snakes
rodents
primates
marsupials
What is Phylogenetics?
Phylogenetics is the study of evolutionary relationships
Example - relationship among species
primates
rodents
birds
crocodiles
marsupials
lizards
snakes
crocodiles
birds
lizards
snakes
rodents
primates
marsupials