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© 2013 Pearson Education, Inc. Lectures by Edward J. Zalisko PowerPoint ® Lectures for Campbell Essential Biology, Fifth Edition, and Campbell Essential.

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Presentation on theme: "© 2013 Pearson Education, Inc. Lectures by Edward J. Zalisko PowerPoint ® Lectures for Campbell Essential Biology, Fifth Edition, and Campbell Essential."— Presentation transcript:

1 © 2013 Pearson Education, Inc. Lectures by Edward J. Zalisko PowerPoint ® Lectures for Campbell Essential Biology, Fifth Edition, and Campbell Essential Biology with Physiology, Fourth Edition – Eric J. Simon, Jean L. Dickey, and Jane B. Reece Chapter 14 How Biological Diversity Evolves

2 Biology and Society: The Sixth Mass Extinction Over the past 540 million years, the fossil record reveals five periods of extinction when 50–90% of living species suddenly died out. Our current rate of extinction, over the past 400 years, indicates that we may be living in, and contributing to, the sixth mass extinction period. Mass extinctions pave the way for the evolution of new and diverse forms, but it takes millions of years for Earth to recover. © 2013 Pearson Education, Inc.

3 THE ORIGIN OF SPECIES When Darwin visited the Galápagos Islands, he realized that he was visiting a place of origins. –Although the volcanic islands were geologically young, they were home to many plants and animals known nowhere else in the world. –Darwin thought it unlikely that all of these species could have been among the original colonists of the islands. Video: Galápagos Islands Overview © 2013 Pearson Education, Inc.

4 In the 150 years since the publication of Darwin’s book On the Origin of Species by Means of Natural Selection, new discoveries and technological advances have given scientists a wealth of new information about the evolution of life. The diversity of life evolved through speciation, the process in which one species splits into two or more species. THE ORIGIN OF SPECIES © 2013 Pearson Education, Inc.

5 What Is a Species? Species is a Latin word meaning –“kind” or –“appearance.” The biological species concept defines a species as “A group of populations whose members have the potential to interbreed with one another in nature to produce fertile offspring.” © 2013 Pearson Education, Inc.

6 Figure 14.2 Diversity within one species Similarity between different species

7 The biological species concept cannot be applied in all situations, including –fossils and –asexual organisms. Some other definitions of species are based on –measurable physical traits, –the use of ecological resources, or –unique adaptations to particular roles in a biological community. What Is a Species? © 2013 Pearson Education, Inc.

8 Figure 14.3 VIABLE, FERTILE OFFSPRING Hybrid breakdown FERTILIZATION (ZYGOTE FORMS) INDIVIDUALS OF DIFFERENT SPECIES MATING ATTEMPT Reduced hybrid fertility Reduced hybrid viability Temporal isolation Habitat isolation Behavioral isolation Mechanical isolation Gametic isolation Prezygotic Barriers Postzygotic Barriers No Barriers

9 Figure 14.3a INDIVIDUALS OF DIFFERENT SPECIES MATING ATTEMPT Temporal isolation Habitat isolation Behavioral isolation Mechanical isolation Gametic isolation Prezygotic Barriers

10 Figure 14.3b VIABLE, FERTILE OFFSPRING Hybrid breakdown FERTILIZATION (ZYGOTE FORMS) Reduced hybrid fertility Reduced hybrid viability Postzygotic Barriers No Barriers INDIVIDUALS OF DIFFERENT SPECIES

11 Prezygotic barriers include –temporal isolation, –habitat isolation, –behavioral isolation, –mechanical isolation, and –gametic isolation. Reproductive Barriers between Species Video: Blue-footed Boobies Courtship Ritual Video: Albatross Courtship Ritual Video: Giraffe Courtship Ritual © 2013 Pearson Education, Inc.

12 Postzygotic barriers operate if –interspecies mating occurs and –hybrid zygotes form. Postzygotic barriers include –reduced hybrid viability, –reduced hybrid fertility, and –hybrid breakdown. Reproductive Barriers between Species © 2013 Pearson Education, Inc.

13 Mechanisms of Speciation A key event in the potential origin of a species occurs when a population is somehow cut off from other populations of the parent species. Species can form by –allopatric speciation, due to geographic isolation, or –sympatric speciation, without geographic isolation. © 2013 Pearson Education, Inc.

14 Speciation occurs with the evolution of reproductive barriers between –the isolated population and –its parent population. Even if the two populations should come back into contact at some later time, the reproductive barriers will keep them as separate species. Allopatric Speciation © 2013 Pearson Education, Inc.

15 Figure 14.8 Geographic barrier Populations interbreed Time Populations become allopatric Populations become sympatric Populations cannot interbreed Reproductive isolation: Speciation has occurred Gene pools merge: No speciation

16 Sympatric Speciation Sympatric speciation occurs in populations that live in the same geographic area. An accident during cell division that results in an extra set of chromosomes is a common route to sympatric speciation in plants. Many polyploid species arise from the hybridization of two parent species. © 2013 Pearson Education, Inc.

17 Many domesticated plants are the result of sympatric speciation, including –oats, –potatoes, –bananas, –peanuts, –apples, –coffee, and –wheat. Sympatric Speciation © 2013 Pearson Education, Inc.

18 What Is the Pace of Speciation? There are two contrasting patterns for the pace of evolution: 1.the gradual pattern, in which big changes (speciations) occur by the steady accumulation of many small changes, and 2.the punctuated equilibria pattern, in which there are –long periods of little apparent change (equilibria) interrupted (punctuated) by –relatively brief periods of rapid change. © 2013 Pearson Education, Inc.

19 Figure Punctuated pattern Gradual pattern Time

20 Figure 14.UN03 Earliest organisms Eukarya Bacteria Archaea

21 © 2013 Pearson Education, Inc. Lectures by Edward J. Zalisko PowerPoint ® Lectures for Campbell Essential Biology, Fifth Edition, and Campbell Essential Biology with Physiology, Fourth Edition – Eric J. Simon, Jean L. Dickey, and Jane B. Reece Chapter 15 The Evolution of Microbial Life

22 Biology and Society: Has Life Been Created in the Lab? How did life first arise on Earth? To gain insight, scientists have –synthesized from scratch the entire genome of a small bacterium known as Mycoplasma mycoides and –transplanted the artificial genome into the cells of a closely related species called Mycoplasma capricolum. © 2013 Pearson Education, Inc.

23 The newly installed genome –took over the recipient cells, –began cranking out M. mycoides proteins, and –reproduced to make more cells containing the synthetic M. mycoides genome. Biology and Society: Has Life Been Created in the Lab? © 2013 Pearson Education, Inc.

24 MAJOR EPISODES IN THE HISTORY OF LIFE Earth was formed about 4.6 billion years ago. Prokaryotes –evolved by about 3.5 billion years ago, –began oxygen production about 2.7 billion years ago, –lived alone for more than a billion years, and –continue in great abundance today. © 2013 Pearson Education, Inc.

25 Single-celled eukaryotes first evolved about 2.1 billion years ago. Multicellular eukaryotes first evolved at least 1.2 billion years ago. MAJOR EPISODES IN THE HISTORY OF LIFE © 2013 Pearson Education, Inc.

26 Figure 15.1a Precambrian Ancestor to all present-day life Origin of Earth Earth’s crust solidifies Oldest prokaryotic fossils Atmospheric oxygen begins to appear Millions of years ago 4,500 4,0003,500 3,0002,500

27 Figure 15.1b Millions of years ago 2,0001,5001,000 Precambrian Oldest eukaryotic fossils Origin of multicellular organisms Oldest animal fossils

28 Figure 15.1c Millions of years ago 1, PrecambrianPaleozoicCenozoic Meso- zoic Bacteria Archaea Plants Fungi Animals Cambrian explosion Oldest animal fossils Plants colonize land Extinction of dinosaurs First humans Protists Prokaryotes Eukaryotes


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