CHAPTER 14 How Biological Diversity Evolves Power Point

CHAPTER 14 How Biological Diversity Evolves Power. Point® Lectures for Essential Biology, Third Edition – Neil Campbell, Jane Reece, and Eric Simon Essential Biology with Physiology, Second Edition – Neil Campbell, Jane Reece, and Eric Simon Lectures by Chris C. Romero Copyright © 2007 Pearson Education Inc. , publishing as Pearson Benjamin Cummings

Biology and Society: One Troublesome Species or Two? • Mosquitoes have assumed a more serious role in public health since the outbreak of West Nile virus. Copyright © 2007 Pearson Education Inc. , publishing as Pearson Benjamin Cummings

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• All mosquitoes look roughly alike. – But close examination reveals many distinct species, two of which may bite birds or people. • DNA comparisons between North American and European species – Have revealed mosquito hybrids in North America that bite both birds and people and are more likely to spread West Nile virus. Copyright © 2007 Pearson Education Inc. , publishing as Pearson Benjamin Cummings

Macroevolution and the Diversity of Life • Macroevolution – Encompasses the major biological changes evident in the fossil record. – Includes the formation of new species. Copyright © 2007 Pearson Education Inc. , publishing as Pearson Benjamin Cummings

• Speciation – Is the focal point of macroevolution. – May occur based

• In nonbranching evolution, a population transforms but does not create a new

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• In branching evolution, one or more new species branch from a parent

• The biological species concept defines a species as – A population or group of populations whose members have the potential to interbreed and produce fertile offspring. Figure 14. 2 b

The Origin of Species • Species is a Latin word meaning “kind” or “appearance.

What Is a Species? Galápagos Sea Lion Galápagos Tortoise Copyright © 2007 Pearson Education

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• The biological species concept cannot be applied in all situations, for example,

Reproductive Barriers between Species • Prezygotic barriers prevent mating between species. Copyright © 2007

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• Prezygotic barriers include – Temporal isolation. – Habitat isolation. – Mechanical isolation. – Gametic isolation. Albatross Courtship Ritual Giraffe Courtship Ritual Blue-Footed Boobies Courtship Ritual Copyright © 2007 Pearson Education Inc. , publishing as Pearson Benjamin Cummings

• Behavioral isolation Copyright © 2007 Pearson Education Inc. , publishing as Pearson

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• Postzygotic barriers – Are mechanisms that operate should interspecies mating actually occur and form hybrid zygotes. Copyright © 2007 Pearson Education Inc. , publishing as Pearson Benjamin Cummings

• Postzygotic barriers include – Hybrid inviability. – Hybrid sterility. Copyright © 2007

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Mechanisms of Speciation • A key event in the potential origin of a species occurs when a population is somehow severed from other populations of the parent species. Copyright © 2007 Pearson Education Inc. , publishing as Pearson Benjamin Cummings

• The two modes of speciation are – Allopatric speciation. – Sympatric speciation.

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Allopatric Speciation • Geologic processes – Can fragment a population into two or more isolated populations. – Can contribute to allopatric speciation. Galápagos Islands Overview Grand Canyon Galápagos Marine Iguana Copyright © 2007 Pearson Education Inc. , publishing as Pearson Benjamin Cummings

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• Speciation occurs only with the evolution of reproductive barriers between the isolated population and its parent population. Copyright © 2007 Pearson Education Inc. , publishing as Pearson Benjamin Cummings

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Sympatric Speciation • Sympatric speciation occurs if a genetic change produces a reproductive barrier between mutants and the parent population. – Polyploidy, a mechanism of sympatric speciation, was first observed by Hugo de Vries. Copyright © 2007 Pearson Education Inc. , publishing as Pearson Benjamin Cummings

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• Polyploids – Can originate from accidents during cell division. – Can result from the hybridization of two parent species. • Many domesticated plants are the result of sympatric speciation. Copyright © 2007 Pearson Education Inc. , publishing as Pearson Benjamin Cummings

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What Is the Tempo of Speciation? • Traditional evolutionary trees diagram the descent of species as gradual divergence. Copyright © 2007 Pearson Education Inc. , publishing as Pearson Benjamin Cummings

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• Punctuated equilibrium – Is a contrasting model of evolution. – States that species most often diverge in spurts of relatively sudden change. – Accounts for the relative rarity of transitional fossils. Copyright © 2007 Pearson Education Inc. , publishing as Pearson Benjamin Cummings

Figure 14. 12 b

The Evolution of Biological Novelty • What accounts for the evolution of biological novelty?

Adaptation of Old Structures for New Functions • Birds – Are derived from a lineage of earthbound reptiles. – Developed from flightless ancestors, but how? Copyright © 2007 Pearson Education Inc. , publishing as Pearson Benjamin Cummings

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• Exaptation – Involves a structure that evolves in one context gradually becoming adapted for other functions. – Is a mechanism for novel features to arise gradually through a series of intermediate stages. Copyright © 2007 Pearson Education Inc. , publishing as Pearson Benjamin Cummings

“Evo-Devo”: Development and Evolutionary Novelty • A subtle change in developmental genes can have

• Paedomorphosis – Is the retention of juvenile body features in the adult.

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Earth History and Macroevolution • Macroevolution – Is closely tied to the history of

Geologic Time and the Fossil Record • The fossil record – Is an archive

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• Geologists have established a geologic time scale reflecting a consistent sequence of geologic periods. The Geologic Record Macroevolution Copyright © 2007 Pearson Education Inc. , publishing as Pearson Benjamin Cummings

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• Radiometric dating – Is the most common method for dating fossils. –

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Plate Tectonics and Macroevolution • The continents are not locked in place. – They drift about Earth’s surface on plates of crust floating on a flexible layer called the mantle. • California’s infamous San Andreas fault – Is at a border where two plates slide past each other. Copyright © 2007 Pearson Education Inc. , publishing as Pearson Benjamin Cummings

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• About 250 million years ago – Plate movements formed the supercontinent Pangaea. – Many extinctions occurred, allowing survivors to diversify. Lava Flow Volcanic Eruption Copyright © 2007 Pearson Education Inc. , publishing as Pearson Benjamin Cummings

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• About 180 million years ago – Pangaea began to break up, causing

Mass Extinctions and Explosive Diversifications of Life • The fossil record reveals an episodic history, – With long, relatively stable periods punctuated by briefer intervals when the turnover in species composition was much more extensive. Copyright © 2007 Pearson Education Inc. , publishing as Pearson Benjamin Cummings

• Extinction is inevitable in a changing world and occurs all the time. – However, extinction rates have not been steady. • Extinctions typically eliminate various species of organisms – And are followed by explosive diversifications of organisms. Copyright © 2007 Pearson Education Inc. , publishing as Pearson Benjamin Cummings

The Process of Science: Did a Meteor Kill the Dinosaurs? • Scientists believe that about 65 million years ago, at the end of the Cretaceous period, – A meteor impact contributed to the extinction of the dinosaurs. Copyright © 2007 Pearson Education Inc. , publishing as Pearson Benjamin Cummings

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Classifying the Diversity of Life • Systematics – Is the study of the diversity and relationships of organisms, both past and present. • Taxonomy – Is the identification, naming, and classification of species. Copyright © 2007 Pearson Education Inc. , publishing as Pearson Benjamin Cummings

Some Basics of Taxonomy • Carolus Linnaeus – Developed the formal naming system used

Naming Species • Each species is assigned a two-part name or binomial, consisting of

Hierarchical Classification • The taxonomic hierarchy Copyright © 2007 Pearson Education Inc. , publishing

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Classification and Phylogeny • The goal of classification is to reflect phylogeny, the evolutionary history of a species. Copyright © 2007 Pearson Education Inc. , publishing as Pearson Benjamin Cummings

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Sorting Homology from Analogy • Homologous structures – Are one of the best sources of information about phylogenetic relationships. Copyright © 2007 Pearson Education Inc. , publishing as Pearson Benjamin Cummings

• Convergent evolution – Involves superficially similar structures in unrelated organisms based on natural selection. • Analogy – Is similarity due to convergence. Copyright © 2007 Pearson Education Inc. , publishing as Pearson Benjamin Cummings

Molecular Biology as a Tool in Systematics • Molecular systematics – Compares DNA and amino acid sequences between organisms. – Can reveal evolutionary relationships. Copyright © 2007 Pearson Education Inc. , publishing as Pearson Benjamin Cummings

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The Cladistic Revolution • Cladistics – Is the scientific search for clades, distinctive branches in the history of life. Copyright © 2007 Pearson Education Inc. , publishing as Pearson Benjamin Cummings

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• Cladistics – Has changed traditional classification of some organisms. Copyright © 2007

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Arranging Life into Kingdoms: A Work in Progress • Linnaeus designed a two-kingdom system of classification, – Which was replaced by a five-kingdom system in the mid-20 th century. Copyright © 2007 Pearson Education Inc. , publishing as Pearson Benjamin Cummings

• In the late 20 th century, – Molecular studies and cladistics led to the development of a three-domain system. Classification Schemes Copyright © 2007 Pearson Education Inc. , publishing as Pearson Benjamin Cummings

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Evolution Connection: Just a Theory? • Certain groups use the idea that evolution is “just a theory” – To discredit its validity and eliminate it from the science curricula in our public schools. Copyright © 2007 Pearson Education Inc. , publishing as Pearson Benjamin Cummings

• The “just a theory” argument has two flaws: – It fails to separate Darwin’s two main ideas. – The term theory has a very different meaning in science than in general use. Copyright © 2007 Pearson Education Inc. , publishing as Pearson Benjamin Cummings