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The Theory of Evolution & Natural Selection
UNIT 7: Chapter 14-18
What is evolution?
A change in species overtime.
The Horse
Over 60 million years, the horse evolved from a dog-sized creature that lived in rainforests into an animal adapted to living on the plains and standing up to 2m high.
In the process, its multi-toed feet, adapted for walking across the forest floor, evolved into single-toed hooves more suited for running over open country.
Charles DarwinDarwin was born in 1809. He sailed around the world (it took 5 years)He searched for scientific explanations for the diversity of life.Sailed on the HMS Beagle.He was a naturalist.
Charles Darwin’s Voyage
Charles Darwin
Wrote a book on the Origin of Species
Sailed with the HMS Beagle
Observations made in the Galapagos Islands
These observations helped him form the theory of how species change over time called natural selection
What did Darwin study?
Finches Tortoises
On the Galopagoes Island
What is Natural Selection?
Natural selection is governed by the principles of genetics.
Also known as “Survival of the Fittest”
Did the Biosphere adapt or evolve over time?
Pinta IslandIntermediate shell
Pinta
Isabela IslandDome-shaped shell
Hood IslandSaddle-backed shellHoodFloreana
Santa Fe
Santa Cruz
James
Marchena
Fernandina
Isabela
Tower
Giant Tortoises of the Galápagos Islands
Section 15-1
Evidence for Evolution
1. Fossil record
2. AnatomyHomologous structures
Analagous structures
3. Vestigial structures
4. Embryology
5. Molecular biology (DNA differences)
Mechanism for change in a population of organisms:
Animals who have greater fitness survive in environment and live to reproduce.
Random changes in DNA (called mutation) can lead to greater or less fitness.
Adaptations allow an organism to survive better in their environment.
Who’s More Fit…..
Bear without claws Bear with claws
Adaptations
large, flat feet, to spread their weight on the sand of their desert habitat
thick fur on the top of the body for shade, and thin fur elsewhere to allow easy heat loss
a large surface area to volume ratio, to maximise heat loss
the ability to go for a long time without water (they don't store water in their humps, but they lose very little through urination and sweating)
the ability to tolerate body temperatures up to 42°C
slit-like nostrils, and two rows of eyelashes, to help prevent irritation from sand.
a white appearance, as camouflage from prey on the snow and ice
thick layers of fat and fur, for insulation against the cold
a small surface area to volume ratio, to minimise heat loss
a greasy coat, which sheds water after swimming
Japanese Spider Crab
Types of Adaptations
Protective ColoringCamouflage
Mimicry
Physiological AdaptationsReproductive Changes
Other changes
Behavioral Adaptations
Peppered Moth Lab
DO NOW---What are some similarities amongst these birds?
Prehistoric Bird Turkey
Lamarck’s Theory of EvolutionSection 15-2
LAMARCK PROPOSED THAT IF AN ORGANISM USED OR DIDN’T USE ORGANS (OR BODY PARTS) WOULD CAUSE IT TO CHANGE OVERTIME. His hypothesis was incorrect!!!
Jean-Baptist Lamarck
French naturalist
Born before Darwin
First to form a hypothesis of evolution.
He finally realized organisms adapt to their environment—don’t loss or gain traits from lack of using organs.
Adaptations
Can arise in response to environmental pressures
Temperature
Antibiotic resistance in bacteria
Pesticide resistance
Morphological changes in peppered moths
Yellowstone Park Environment
America’s first national park
Variety of wildlife (grizzly bears, wolves, bison, elk)
Preserved national park
Located in Wyoming, Montana and Idaho
Bacteria can survive in 400 degrees F. This is an example of adaptation.
http://www.yellowstoneparknet.com/geothermal_features/hot_springs.php
What is a Population?
Populations are groups of interbreeding individuals that live in the same place at the same time.
Populations evolve over many generations, individuals don’t!
Individuals in a population compete for resources with each other.
How Does Evolution Work?
Populations produce more offspring than the environment can support.
The unequal ability of individuals to survive and reproduce leads to the gradual change in a population over many generations.
How are new species created?
Geographic isolation
Reproductive barriers
Change in chromosome numbers
Adaptive radiation
What is Extinction?
The Dodo Bird
Review Evolution:
1. What is evolution?
2. What is natural selection?
3. Who was Charles Darwin?
4. What are 5 evidences that support evolution?
5. Describe a younger and older fossil and ground layers they would be fossilized in.
Answers
1. A change in species overtime. 2. Favorable variations that enables an organism to
adapt successfully to a change in the environment.
3. He formed theory of evolution—species change overtime.
4. Fossil record, Anatomy, Vestigial structures, Embryology, Molecular biology
5. Younger layer would be in top ground sediment. Older layer would be below younger layer of fossil remains.