15-3 Darwin Presents His Case

15-3 Darwin Presents His Case
Photo Credit: Art Wolfe Incorporated Copyright Pearson Prentice Hall

Publication of On the Origin of Species
He shelved his manuscript for years and told his wife to publish it in case he died. In 1858, Alfred Wallace sent an essay to Darwin for review. Wallace’s ideas summarized Darwin’s work. In 1859, Darwin published his book, On the Origin of Species. Copyright Pearson Prentice Hall

Publication of On the Origin of Species
In his book, Darwin: proposed a mechanism for evolution called natural selection. presented evidence that evolution has been taking place for millions of years—and continues in all living things. Copyright Pearson Prentice Hall

Inherited Variation and Artificial Selection
Members of each species vary from one another in important ways. Darwin noted that plant and animal breeders would breed only the largest hogs, the fastest horses, or the cows that produced the most milk. Darwin termed this process artificial selection. Copyright Pearson Prentice Hall

Artificial selection is the selection by humans for breeding of useful traits from the natural variation among different organisms. Copyright Pearson Prentice Hall

Cauliflower Brussels Sprouts Broccoli In artificial selection, humans select from among the naturally occurring genetic variations in a species. From a single ancestral plant, breeders selecting for enlarged flower buds, leaf buds, leaves, or stems have produced all these plants. Ancestral Species Kohlrabi Kale Copyright Pearson Prentice Hall

Evolution by Natural Selection
Darwin compared processes in nature to artificial selection. By doing so, he developed a scientific hypothesis to explain how evolution occurs. Heritability is the ability of a trait to be passed down. Copyright Pearson Prentice Hall

The Struggle for Existence Darwin realized that high birth rates and a shortage of life's basic needs would force organisms to compete for resources. There is a struggle for survival due to overpopulation and limited resources. Copyright Pearson Prentice Hall

How is natural selection related to a species' fitness? Copyright Pearson Prentice Hall

Variation The heritable differences that exist in every population are the basis for natural selection. Copyright Pearson Prentice Hall

Survival of the Fittest The ability of an individual to survive and reproduce in its specific environment is fitness. Darwin proposed that fitness is the result of adaptations. An adaptation is any inherited characteristic that increases an organism's chance of survival. Copyright Pearson Prentice Hall 11

Because of its similarities to artificial selection, Darwin referred to the survival of the fittest as natural selection. In natural selection, the traits being selected contribute to an organism's fitness in its environment. Copyright Pearson Prentice Hall

Over time, natural selection results in changes in the inherited characteristics of a population. These changes increase a species' fitness in its environment. Copyright Pearson Prentice Hall

Descent With Modification Natural selection produces organisms that have different structures, establish different niches, or occupy different habitats. Each living species has descended, with changes, from other species over time. Darwin referred to this principle as descent with modification. Copyright Pearson Prentice Hall

Copyright Pearson Prentice Hall

Overproduction Having many offspring increases the chance of survival but also results in competition for resources. Copyright Pearson Prentice Hall 16

Evidence of Evolution What evidence of evolution did Darwin present? Copyright Pearson Prentice Hall

Evidence of Evolution Evidence of Evolution Darwin argued that living things have been evolving on Earth for millions of years. Evidence for this process include: the fossil record geographical distribution anatomy similarities in early development, or embryology. Copyright Pearson Prentice Hall

Evidence of Evolution The Fossil Record Darwin saw fossils as a record of the history of life on Earth. By comparing fossils from older rock layers with fossils from younger layers, scientists could document that life on Earth has changed over time. The older the fossil, the more it will be covered with more layers of rock. Copyright Pearson Prentice Hall

Evidence of Evolution Geography- Island species most closely resemble species on the nearest mainland, and populations can show variations from one island to the next. The existence of similar but unrelated species was a puzzle to Darwin. Later, he realized that similar animals in different locations were the product of different lines of evolutionary descent. Here, the beaver and the capybara are similar species that inhabit similar environments of North America and South America. The South American coypu also shares many characteristics with the North American muskrat. Copyright Pearson Prentice Hall

Evidence of Evolution Similarities in Embryology The early stages, or embryos, of many animals with backbones are very similar. The same groups of embryonic cells develop in the same order and in similar patterns to produce the tissues and organs of all vertebrates. Pharyngeal pouches Post-anal tail Chick embryo (LM) Human embryo Copyright Pearson Prentice Hall

Embryology Copyright Pearson Prentice Hall

Evidence of Evolution Anatomy Anatomy is the branch of science that bodily structures and parts of humans, animals and other organisms. Features that are similar in structure but appear in different organisms and have different functions are called homologous structures. Homologous structures are evidence of a common ancestor. Copyright Pearson Prentice Hall

Evidence of Evolution-Anatomy
Homologous Structures- Turtle Alligator Bird Mammal The limbs of these four modern vertebrates are homologous structures. They provide evidence of a common ancestor whose bones may have resembled those of the ancient fish shown here. Notice that the same colors are used to show related structures. Homologous structures are one type of evidence for the evolution of living things. Homologous structures are one type of evidence for the evolution of living things. Ancient, lobe- finned fish Copyright Pearson Prentice Hall

Evidence of Evolution Not all homologous structures serve important functions. Remnants of organs or structures that had a function in an early ancestor are called vestigial organs. Copyright Pearson Prentice Hall

Analogous Structures-have a similar function but different internal structures and embryonic development. They do not share a common ancestor Copyright Pearson Prentice Hall

Evolutionary Theory Evolutionary Theory Scientific advances in many fields of biology, geology, and physics have confirmed and expanded most of Darwin’s hypotheses. Evolutionary theory continues to change as new data are gathered and new ways of thinking arise. Copyright Pearson Prentice Hall

Natural Selection is explained by Variation Overproduction Adaptation Descent with modification Copyright Pearson Prentice Hall

And… Evidence for evolution includes The fossil record Anatomy Adaptation-geographical distribution Embryology/biochemistry Copyright Pearson Prentice Hall

Hummingbirds have long hollow beaks that they use to probe flowers for nectar. The beak protects the tongue which slurps up the nectar. Copyright Pearson Prentice Hall

Curlews, godwits, kiwis, and snipes have very long beaks that they use to probe for worms, crustaceans, and other small creatures in mud and water. Copyright Pearson Prentice Hall

Spoonbills and pelicans have long, flattened or pouchlike beaks that they use to scoop up fish and other aquatic creatures. Copyright Pearson Prentice Hall

Cardinals, sparrows, grosbeaks, and other finchlike birds have very short, conical beaks. These beaks are very strong and can break open tough seeds. Copyright Pearson Prentice Hall

Puffins have thick, curved bills in which they hold small fish crosswise with their tongue while diving for more. Copyright Pearson Prentice Hall

Warblers have small, sharp, pointed beaks for picking insects from leaves, logs, and twigs. Copyright Pearson Prentice Hall

Nighthawks, whip-poor-wills, swifts, and swallows have large, gaping mouths that act like nets to trap insects. These birds catch insects on the wing. Copyright Pearson Prentice Hall

Flamingos and some ducks have bills that act like strainers to filter tiny plants and animals from the water. Copyright Pearson Prentice Hall

15-3 Copyright Pearson Prentice Hall

15-3 The scientist who motivated Darwin to publish On the Origin of Species was Alfred Russel Wallace. Charles Lyell. Jean-Baptiste Lamarck. Thomas Malthus. Copyright Pearson Prentice Hall

15-3 Differences among individuals of a single species are referred to as artificial selection. genetic variation. survival of the fittest. environmental adaptation. Copyright Pearson Prentice Hall

15-3 Changes that increase a species' fitness in its environment over time are due to the principle of common descent. the geographic distribution of that species. natural selection. habitat selection. Copyright Pearson Prentice Hall

15-3 An inherited characteristic that increases an organism's chance of survival is called a(an) homologous structure. vestigial organ. adaptation. analogous structure. Copyright Pearson Prentice Hall

15-3 Evidence used by Darwin to support the idea of evolution included all the following EXCEPT fossils that demonstrate change over time. the genetic mechanism by which useful traits are inherited. the geographic distribution of living things. the presence of many homologous structures in plants and animals. Copyright Pearson Prentice Hall

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15-3 Darwin Presents His Case

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