Download Changes Over Time Slide Show Notes

CHANGES OVER TIME
Unit Preview
• Darwin’s Theory
• Evidence of Evolution
• The Fossil Record
Darwin’s Theory
• What important observations did Darwin make on his voyage?
• What hypothesis did Darwin make to explain the differences between similar species?
• How does natural selection lead to evolution?
Key Terms
___________________________A trait that helps an organism survive and reproduce.
___________________________The gradual change in a species over time.
___________________________The preserved remains or traces of an organism that lived in the past.
___________________________Individuals that are better adapted to their environment are more likely to
survive.
___________________________A well-tested concept that explains a wide range of observations.
___________________________A group of similar organisms that can mate with each other and produce
offspring.
___________________________Any difference between individuals of the same species.
Charles Darwin
• A “______________________” – studied the natural world.
• Sailed on the ___________________ to the Galapagos Islands.
• Observed many unusual organisms on the island.
* ____________________________
* Blue-footed booby
* ____________________________
The Voyage of the Beagle
• The Beagle made many stops along the coast of _________________________ stopping at the
Galapagos Islands.
• Darwin observed living things as he traveled and tried to make connections about the relationships
among those organisms.
* Diversity of _____________________ things
* Remains of ancient organisms
*__________________________ characteristics of organisms on the Galapagos.
Darwin’s Observations
• The theory of EVOLUTION by NATURAL SELECTION
• Evolution - The gradual change in a species over time.
• Natural Selection - Individuals that are better adapted to their environment will survive and reproduce.
DIVERSITY
• The variety of life on Earth.
• Darwin was amazed by the tremendous diversity of living things that he saw.
• Scientists have identified more than __________________ million species of organisms on Earth.
FOSSILS
• The preserved remains or traces of an organism that lived in the past.
• Darwin was puzzled by some of the fossils he observed.
• He saw ________________________ ________________________ of animals that had died long ago
but yet resembled the bones of organisms alive in Darwin’s time.
Galapagos Organisms
• Darwin observed many unusual life forms on these small islands.
• He compared Galapagos organisms to organisms that lived elsewhere.
• He also compared organisms on different islands in the Galapagos group.
• He tried to make _________________ using the __________________ and ____________________ he
observed.
Comparisons to South American Organisms
• The Galapagos organisms resembled many of those in ___________________________.
• Important differences between the organisms on the _____________________ and those on the
___________________ were important in determining how the species ended up on the islands.
• Darwin hypothesized that a small number of different plant and animal species had come to the
Galapagos Islands from the mainland.
* Blown out to sea during a storm
* Set adrift on a fallen log
• Once on the islands, the organisms reproduced and over time, their _________________________
became different from their mainland relatives because of their environment.
IGUANAS
• The iguanas on the Galapagos Islands had ___________________ claws.
* Grip slippery rocks.
* Feed on _________________________.
• The iguanas on the mainland had smaller claws.
* Climb trees.
* Eat leaves.
Comparisons among the Islands
•Darwin noticed many differences among organisms as he traveled from one island to the next.
•Darwin was able to ______________________ which island an organism came from just by
______________________ at it.
TORTOISES
• Some had ____________________-shaped shells.
• Some had ______________________-shaped shells.
• Tortoises lived inland and became like “land-dwelling mammals” grazing on vegetation.
GALAPAGOS FINCHES
• Each species was well ____________________________ (suited) to the life it led.
• Beak shape was based on their ___________________.
* Narrow, needle-like beaks = _______________________
* Strong, wide beaks = ________________________
Adaptive Radiation
• The evolutionary diversification of a single lineage into a variety of species with different adaptive
properties.
Theory of Evolution
• Darwin spent __________________ years consulting with other scientists, gathering more information,
and re-evaluating his observations from his trip on the ________________________ before he developed
his theory of evolution.
• Plants or animals faced with different conditions will gradually change over many
______________________ in order to become better adapted to their conditions.
Selective Breeding
• The process of selecting a few _______________________ with desired traits to serve as
_____________________ of the next generation.
• By repeatedly allowing only organisms with the desired traits to reproduce, the more desirable trait
becomes __________________________ and highly favorable in the offspring.
• Darwin made connections between the practice of selective ________________________ and organism
behavior in nature as evidence for his theory of evolution.
Natural Selection
• In _________________, Darwin proposed an explanation for how evolution could occur in nature.
• Evolution occurs by means of ___________________________
___________________________.
Natural selection is the process by which individuals that are better adapted to their environment are more
likely to survive and reproduce than other members of the same species.
Factors Affecting the Process of Natural Selection
•
•
•
•
•
•
OVERPRODUCTION
• Most species produce far more __________________________ than can possibly survive.
• A large number of offspring creates _____________________________ for resources.
VARIATIONS
• Members of a species differ from one another in many of their _____________________.
• Variations are linked to ___________________________ conditions.
COMPETITION
• Limited _______________________ creates _______________________ among members of a species.
• Direct
* Ex. - ________________________
• Indirect
* Ex. - ________________________
* Ex. - ________________________
SELECTION
• Some variations make individuals better adapted to their environment.
• Individuals who are better adapted ________________________ and __________________________.
• Helpful variations may gradually accumulate in a species, while ___________________________ ones
may disappear.
ENVIRONMENTAL CHANGE
• A change in the environment can affect an organism’s ability to survive.
• The environmental change can __________________________________ lead to selection.
• The Galapagos Islands are a prime example of how the environment can lead to the
__________________________________ of a species by natural selection.
GENES
• Without variations, all the members of a species would have the __________________________ traits.
• _________________
___________________ would not occur because all the individuals would have
an equal chance of surviving and reproducing.
• Variations can result from ___________________________ and the shuffling of alleles during
__________________________.
• Genes are passed from __________________________ to offspring.
Natural Selection . . .
. . . ______________of the______________!