how many species of spiders do you see?

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How many species of spiders do you see?

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How many species of spiders do you see?. Vocabulary so we are all on the same page…. Species: group of organisms that breed with one another and produce fertile offspring Share a common gene pool , largest gene pool possible Speciation – formation of a new species - PowerPoint PPT Presentation

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Page 1: How many species of spiders  do you see?

How many species of spiders do you see?

Page 2: How many species of spiders  do you see?

Vocabulary so we are all on the same page…

Species: group of organisms that breed with one another and produce fertile offspringShare a common gene pool, largest gene pool

possible

Speciation – formation of a new speciesThe shared gene pool is eventually split

Page 3: How many species of spiders  do you see?

Reproductive IsolationReproductive Isolation – when members of

two populations can no longer interbreed and produce fertile offspring

New species form when organisms are reproductively isolated.

REPRODUCTIVE ISOLATION is the KEY to SPECIATION!

Page 4: How many species of spiders  do you see?

First a little story about our friend the squirrel…

Page 5: How many species of spiders  do you see?

Geographic IsolationPopulations become

separated by geographic barriers such as rivers, mountains, or other bodies of water.

The Grand Canyon

Kaibab SquirrelAbert Squirrel

Page 6: How many species of spiders  do you see?

The Gene Pools must separate to become a new species

There is no gene flow between the populations

AND

Over time, the populations respond to new variations and natural selection as separate units

Page 7: How many species of spiders  do you see?

Speciation

Reproductive IsolationGeographical Isolation Temporal IsolationBehavioral Isolation

The squirrels

Page 8: How many species of spiders  do you see?

Reduction of gene flow

Page 9: How many species of spiders  do you see?

Temporal IsolationTemporal Isolation – occurs when two or

more subspecies reproduce at different times

Day Blooming/Night Blooming

Eastern and Western Spotted Skunks

Page 10: How many species of spiders  do you see?

Speciation

Reproductive IsolationGeographical Isolation Temporal Isolation Behavioral Isolation

The squirrels

The Skunks

Page 11: How many species of spiders  do you see?

Behavioral IsolationBehavioral Isolation –capable of

interbreeding BUT have different reproductive strategies

Western Meadowlark

Eastern Meadowlark

Page 12: How many species of spiders  do you see?

Speciation

Reproductive IsolationGeographical Isolation Temporal Isolation Behavioral Isolation

The squirrels

The Meadowlarks

The Skunks

Page 13: How many species of spiders  do you see?

What type of Isolation is under way? http://www.pbs.org/wgbh/nova/beta/evolution/evolution-action-salamanders.ht

ml

Page 14: How many species of spiders  do you see?

How many species of spiders do you see?

THE HAPPY FACE SPIDERS!Look different but CAN

interbreed!

Page 15: How many species of spiders  do you see?

What about the ligers and mules?

Are there any other gray areas for the definition of a species?

Page 16: How many species of spiders  do you see?

Testing the Speciation Hypothesis in nature1995 Hurricane brought the Iguana iguana

species to a new island in the Caribbean

Will it go extinct?Will the gene pool remain unchanged?Will it respond to new selection

pressures and become reproductivelyIsolated?

Page 17: How many species of spiders  do you see?

Testing the Speciation Hypothesis ArtificiallySeparate cages act as what?

Develop food preferences

Mate and lay eggs on different food sources

Can lead to the start of what?

Page 18: How many species of spiders  do you see?

Test your understanding-Explain how geographical and reproductive isolation work together with mutations to cause variation within a species and possibly speciation.