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Transcript
Chapter 15
{
Evolution


Evolution: change over time
Scientific Theory: a well supported testable
explanation of a phenomena that has occurred
in the natural world
15-1 The Puzzle of Life’
Diversity


Born in 1809
Has contributed the most to evolution



set sail in 1831 from England
lasted 5 years
was the most important voyages in scientific history
Charles Darwin

Made many observations during his travel

got this theory by investigating plants & animals
in different places

Galapagos Islands(off coast of S. America)
Charles Darwin


Noticed many animals were well suited to their
environment
Noticed some animals were only found in
certain places even though other places had
same ecosystem
Charles Darwin

Collected fossils

He wondered where all these species had gone
and who they might be related to…
Charles Darwin

The Galapagos Islands influenced Darwin
more than any other place in the world
The Galapagos Islands
The Galapagos Islands


Galapagos Islands were very close together
But had very different climates.


Smallest island was hot and dry and barren
Others had rich vegetation and many animals
like tortoises.
Charles Darwin

Darwin learned that the tortoises varied based on the island
they came from


Could be told apart by shell
Also shape of a birds beak varied depending on island of origin
The Galapagos Islands

He wondered if these different animals had
once been of the same family???
The Galapagos Islands

In 1858 Alfred Wallace pushed him to publish
thought because he to came up with same
theories. Called On the Origin of Species.
Darwin’s Book



Artificial Selection- nature provides the
variation, human selects the best to breed
Natural Selection- change over time in
inherited characteristics. “Survival of the
fittest”
Natural variation- differences among
individuals of a species. Variation is inherited
Darwin’s Ideas


FitnessSurvival of the Fitness -

Adaptations- special characteristics that make
and organism well suited for a particular
environment


Cont.
If disease affects only short people…what will
happen
If survivors all mated and reproduced what
traits would offspring have?

Mix because of heterozygous…short people
would start to die out. In 1,000 years what do
you expect?
Only tall would survive an short wouldn’t be
produced

1. Individual organisms differ



some variation due to inheritance
2. Organisms produce more offspring than can
survive and many that do survive don’t
reproduce
3. More organisms are produced than can
survive = competition for limited resources

4. Each organism had advantages &
disadvantages


Best suited survive and reproduce AND pass
traits down
5. Species today are decedents with
modifications from ancestral species. We are all
united and thus we have common descendants
Summary Cont.
What did I evolve into???
Whale
Guess????
Who am I related to????
Hermit Crab
Why am I called Ice
Fish
Has antifreeze glycoprotein
so survive in freezing water


Some thought Darwin was crazy.
People thought:



the world was only a few hundred years old
that all species were the same NOW as in
beginning
Rocks and geological features were created by
catastrophic events that no human saw
15-2 Ideas that shaped
Darwin’s thinking

By the time he set sail new ideas were being
formed by other scientists

Hutton and Lyell


the world was a few million years old not a few
hundred.
geological processes are still occurring today

Ie volcanoes, erosion, earthquakes, sea floor being
pushed up, mountains created
Hutton and Lyell
•
recognized that living things change over time
•
all species are descendents from one another and
that they adapt to their environment
Lamarck

Also that organisms acquire or lose traits in their
lifetime. These traits can be passed to offspring
Lamarck Cont.

1. Innate tendency towards perfection


2. Use and disuse


continually changing
can alter size and shape..add or remove features
3. Inheritance of acquired traits

example: if parents grew longer…passed on to
kids
Lamarck Cont.

Thomas Malthus 1798

If population continues to grow we will run out
of food and space
Malthus




1. Fossil records- gradual change over time
2. Geographical distribution of living species
3. Homologous structures of living organisms
4. Similarities in early development
Evidence of Evolution and
shared common ancestors