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Transcript
Adaptations and Natural
Selection
By: Mr. Lowe
Important Vocabulary
• Species = Group of organisms who
share similar characteristics and can
reproduce among themselves.
• Evolution = Change in inherited (from
DNA) characteristics over time.
Theory of Acquired
Characteristics
(Jean Baptiste de Lamarck)
• Traits or
characteristics
developed during an
organisms lifetime
are passed on to
their offspring.
The “tall” Giraffe would then have tall babies!
No way dude!!!!!
Charles Darwin
(1809-1882)
• Charles Darwin was a naturalist
who sailed around the world in
1831.
• One of the places he helped
explore was the Galapagos
Islands off the coast of South
America.
• On the Galapagos Darwin
observed many, diverse,
species of animals.
• Darwin observed many types of finches that
resembled a species from South America.
• Each of these finches was well adapted for the local
food source.
• Darwin also observed different versions of the Giant
Tortoise. They had also adapted to their environment.
• Based on what he observed Darwin began to develop his
Theory of Natural Selection…
Important Vocabulary
• Variation = DNA inherited trait that
makes an individual different than others
of its species.
• Adaptation = Any variation that makes an
organism better suited to its environment.
Mimicry
Camouflage
Camouflage
Camouflage
Principals of Natural Selection
1.Organisms produce more offspring than survive.
2. Differences, or variations, occur among individuals
of a species
3. Variations are passed to offspring.
4. Some variations are helpful. Individuals with helpful
variations survive and reproduce.
5. Over time the offspring of individuals with helpful
variations make up more and more of a population
and eventually become a separate species.
Clues About Evolution
We have many clues that evolution has
occurred and continues to occur with living
organisms. Some of these clues are:
•
•
•
•
•
Fossils
Embryology
Homologous Structures
Vestigial Structures
DNA
Fossils
• Fossils = The exposed remains or imprints of
long dead plants, animals, or other living
organisms.
• Most fossils are found in sedimentary rock.
• This is rock formed from mud and silt from long
dried up rivers and oceans.
Age of Fossils
• How do we know how old fossils are?
a. Relative Dating: (How deep it’s
buried) The deeper it is the older it is.
b. Radiometric Dating: Radioactive elements in
the rock are used to accurately date the
contents of the rock.
Embryology
• Embryo = earliest growth stage of
development.
• Embryology = Studying the similarities in
embryos of different species.
Homologous Structures
• Homologous structure = Similar in origin and
structure. Common traits among many
organisms.
Vestigial Structures
• Vestigial Structure = Structures that remain
on the body, but have no apparent function.
DNA
• Similarities in DNA
content and structure.
• Ape = 24 pairs of
chromosomes.
• Human = 23 pairs of
chromosomes.
• Human and
Chimpanzee = 96%
identical DNA.
Clues!!!!
• No one thing states that evolution takes
place! Many things do!
• Indirect Evidence – “Clues” give us a
picture of how living organisms might have
changed (evolved) over million of years.