Download Why do animals become extinct? - Etiwanda E

Change Through Time
By: Susan Karikas
How did we get here from there?
• Mechanisms of evolution
– Millions of different organisms inhabit our planet
– Species reproduce their own types
– Since the beginning of time organisms have
changed and continue to change
Who thought of this stuff?
• Jean Baptiste de Lamarck
– Early evolution theorist (1809)
– French scientist hypothesized that offspring
inherit traits that their parents developed
throughout their life.
• Weight lifters develop muscle through hard work
and not inheriting from their parents
Charles Darwin’s visit to the
Galapagos Islands
• At the age of 22, Charles Darwin sailed on
the HMS Beagle to South America
• He observed and recorded facts about
plants, animals, and fossils
– Giant cactuses, 13 species of finches, and huge
land turtles
• He collected specimens
– For 20 years he studied his specimens to come
up with his hypothesis
Principles of Natural Selection
• Organisms with traits best suited to their
environment are more likely to survive and
reproduce
• Five factors involved in natural selection
– Organisms produce more offspring than can
survive; variations exist within species; these
variations are passed on to offspring; some
variations allow members of a population to
survive; over time these helpful variations make
up more of a population
Adaptation and Variation
• A variation is an inherited trait that makes
one member different from another of the
same species. Variations result in mutation
of one’s DNA.
– An example could be as simple as the shape of
one’s hairline or as complex as fruits without
seeds
• Some variations are more helpful than
others
• Variations result in adaptations
Adaptations
• An adaptation is any variation that makes an
organism better suited to its environment
– Camouflage is an adaptation that allows an
organism to blend into its environment and thus
have a better chance of surviving and passing
on helpful traits to its offspring
How fast does evolution occur?
• Scientists have different hypotheses on this
issue.
– Many believe evolution occurs over millions of
years
• Gradualism
– Others believe change occurs more quickly
• Punctuated equilibrium
• Evidence supports both models
Models of change: Gradualism
and Punctuated Equilibrium
• Gradualism states that evolution is a slow,
steady and ongoing process
– Change of one species to another
– Intermediate form of all species
• Punctuated Equilibrium states that evolution
can occur more quickly through mutations
in DNA
– An example of this model is bacteria that is
destroyed by antibiotics
How do we know this is true?
• Fossil evidence
– Any evidence of life from an earlier geological
time
– Imprints of a leaf, feather, or organism in a rock
– A piece of wood or bone
– An organism frozen in ice
– An insect or organism trapped in amber (think
Jurassic Park)