Download Changes in Living Things Notes

Changes in Living Things
Over Time
Changes Over Time
• In order for a species to survive, in an ever
changing environment, they must change
as well – evolution.
– As scientists study organisms from the past
and compare them to organisms that currently
live on the planet, they have discovered many
evidences that organisms have gradually
changed over time.
• If a species does not change (adapt) it will
ultimately die and the species will become extinct.
Evidence of Evolution
• Evidence that supports the theory of
evolution :
1.
2.
3.
4.
5.
Fossil Evidence
Radioactive Dating
Law of Superposition
Anatomical Evidence
Chemical Evidence
1. Fossil Evidence
• Remains of a once living thing.
• Bone, print, shelter, pollen, seeds
– Not the complete organism but only the hard parts.
2. Radioactive Dating
• Measures the age of a fossil through
radioactive elements.
– Decay rate of radioactive element = half life.
• Half life = amount of time for half the element to
decay.
C14 half lives
1 half life = 5730 yrs
2 half lives = 11460 yrs
3 half lives = 17190 yrs
4 half lives = 22920 yrs
5 half lives = 28650 yrs
www.ipj.gov.pl/
3. Law of Superposition
• Where an
organism’s fossils
can be found in the
rock record.
– Youngest on top
• The most recent event
to occur
– Oldest on the
bottom
• The earliest event to
occur
www.sd41.k12.id.us/
4. Anatomical Evidence
• Jean-Baptiste de Lamarck
(early 1800’s)
– Concluded: living things
had changed over time.
– Homologous structures –
body parts of different
organisms with similar
structures.
• Human arm, bat wing,
whale flipper and dog
leg
– Things did evolve thus
becoming better adapted
for their environment.
www2.visalia.k12.ca.us/
Anatomical Evidence
• Lamark’s downfall!
– Believed that body structures change
because of an inborn will to change and
use.
• Birds – had the desire to fly and over time thus
developed wings
• Giraffe neck- Started off short but with continual
stretching it lengthened.
– Eventually lost all credibility because of this.
www.bellrevolution.com/
6. Chemical Evidence
• DNA is the basic unit of heredity.
– More similar the DNA = more closely related
the organisms.
• Human vs. Human = 100%
• Human vs. Chimpanzee = 98%
• Human vs. Mouse = 92%
• Protein molecule similarities can also
determine common ancestors.
– Scale of protein change = molecular clock
• Who is the common
ancestor to the Trachodon
and Triceratops?
Camptosaurus
• Who is more closely
related:
– Trachodon and Stegosaurus
– Apatosaurus and Triceratops
– Thrannosaurus and
Coelophysis
– Coelophysis and Theodont
Split most recently from each
other
Natural Selection
• Charles Darwin
– 1831, 5yr voyage on the
Beagle
• Studied plants and animals
• Galapagos – noticed
difference between island and
mainland creatures.
– Perfectly adapted to survive
in a particular environment.
– 1858 – Published On the Origin
of Species
• Stated his theory of evolution –
natural selection
www.charlesdarwinresearch.org/
Natural Selection
• Natural Selection – survival and reproduction of
those organisms best adapted to their surroundings.
– 2 ways:
1. Overproduction - Producing more offspring
than can survive.
•
•
Competition for both food and shelter
Those best adapted will survive and reproduce
– survival of the fittest!
–
The fittest are selected by their surroundings
Overpopulation
Salmon eggs
Tadpoles
Dandelion Seeds
Variation
2. Variation - No two members of a
species are exactly alike.
– Polar Bears – fur thickness
•
Survival of temperature variation is dictated by
fur.
– Peppered Moths – body colors
•
Pollution levels change bark colors – camouflage
determines survival.
Variation
Polar Bear fur thickness
Peppered Moths
color
Mouse color