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The Origin of Species Chapter 22.

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Presentation on theme: "The Origin of Species Chapter 22."— Presentation transcript:

1 The Origin of Species Chapter 22

2 The Origin of Life Alexander Oparin and coacervates
Theory that extends evolution back to the Earth’s beginning to explain how life began.

3 The Biological Species Concept
Individuals in the population can mate and produce fertile offspring Individuals in different populations would mate and produce fertile offspring if they came in contact naturally. Liger

4 The Nature of Species Two types of speciation:
Sympatric Allopatric Within species you also have subspecies.

5 Reproductive Isolating Mechanisms
There are two types: Prezygotic isolating mechanisms Geographic isolation Ecological isolation Behavioral isolation Temporal isolation Mechanical isolation

6 Behavioral isolation Temporal Isolation Breeds Jan - March
Breeds late March - May

7 Mechanical Isolation

8 Reproductive Isolating Mechanisms
2. Postzygotic Isolating Mechanisms - “Processes that prevent hybrid zygotes from developing into normal, functioning, fertile adults”.

9 Problems with the Biological Concept
How reproductively isolated are the species? Difficult to apply to allopatric populations. Doesn’t apply to asexual species. Alternative: Ecological Species Concept

10 Geography of Speciation
Speciation is a 2-part process Initially identical populations must diverge Reproductive isolation must evolve to maintain these differences a. b. c.

11 Allopatric Speciation
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Allopatric Speciation Isolated island population of kingfishers Isolated island population of kingfishers Mainland population of kingfishers NEW GUINEA PACIFIC OCEAN Isolated island population of kingfishers Mainland population of kingfishers

12 Sympatric speciation

13 Speciation Adaptive Radiation:
Character Displacement: “Natural selection favors those individuals that use resources not used by other species” Adaptive Radiation: “Closely related species that have recently evolved from a common ancestor by adapting to different parts of the environment”

14 Adaptive Radiation

15 Character Displacement

16 Adaptive Radiation and Darwin’s finches
Ancestors reached these islands before other land birds. Ground finches Tree finches Vegetarian finch Warbler finches

17 The Pace of Evolution

18 Speciation and Extinction
Speciation, through time, has surpassed extinction Five mass extinctions have occurred.

19 Speciation and Extinction
Not all groups are affected equally by mass extinctions. Previously dominant groups may perish, changing the course of evolution. The 6th extinction is currently underway.


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