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Darwin’s Theory of Evolution

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Presentation on theme: "Darwin’s Theory of Evolution"— Presentation transcript:

1 Darwin’s Theory of Evolution

2 16.1 Darwin’s Voyages of Discovery
Definition of Evolution Change in a kind of organism over time. Process by which modern organisms have descended from ancient organisms. In biology, the noun evolution means “the process by which organisms have changed over time.” The verb evolve means “to change over time.” 4/22/2017

3 Darwin’s Epic Journey Individual who contributed the most to our understanding of evolution. In 1831, he set sail from England for a voyage around the world. He developed a scientific theory of biological evolution that explains how modern organisms evolved over long periods of time through descent from common ancestors. 4/22/2017

4 Collected and catalogued biological specimens for return to England.
Darwin was a naturalist aboard an exploration ship called the HMS Beagle. Collected and catalogued biological specimens for return to England. Charles Darwin’s Book The Origin of Species / 4/22/2017

5  Darwin’s Voyage Section 15-1 On a 5 year voyage on the H.M.S.Beagle, Darwin visited several continents and many remote islands. Watch Video#2 PBS 4/22/2017

6 Observations Aboard the Beagle
What 3 patterns of biodiversity did Darwin Note? 1. Species vary globally. 2. Species vary locally. 3. Species vary over time. Refer to Figures 16-1, 16-2, 16,3 4/22/2017

7 Species Vary Globally Read Page 451 4/22/2017

8 Species Vary Locally Read Page 452 4/22/2017

9 Species Vary Over Time Read Page 4/22/2017

10 16-2 Ideas That Shaped Darwin’s Thinking
Hutton and Lyell –Refer to Fig and Read Pages Jean Baptise Lamark –Refer to Fig 16-6 Read page 456 Thomas Maltus –Refer to Fig 16-7 Read page 457 4/22/2017

11 Lamarck’s Theory of Evolution
Jean-Baptise Lamarck was among the first scientists to recognize that living things have changed over time and that all species were descended from other species. He proposed that by selective use or disuse of organs, organisms acquired or lost certain traits during their lifetime. These traits could then be passed on to their offspring. This process led to change in a species. 4/22/2017

12 Lamarck’s Theory of Evolution
Section 15-2 Refer to Page 459 Discuss Artificial Selection 4/22/2017

13 What is the Theory of Evolution
Lamarck vs. Darwin Lamark vs DarwinVideo What is the Theory of Evolution 4/22/2017

14 16-3 Darwin Presents His Case
Evolution by Natural Selection Struggle for existence - members of each species compete regularly to obtain food, living space, and other necessities of life. Variation and Adaptation - any heritable characteristic that increases an organism’s to survive and reproduce in its environment is called an adaptation. Fig 16-9 Survival of the Fittest - process by which individuals that are better suited to their environment survive and reproduce most successfully; also called natural selection. Natural Selection – Occurs in any situation in which more individuals are born that can survive (struggle for existence), there is natural heritable variation (variation and adaptation), and there is a variable fitness among individuals (survival of the fittest) 4/22/2017

15 The Struggle for Existence
Organisms produce more offspring than can survive. Grasshoppers can lay over 200 eggs at a time. Only a small fraction of these offspring survive to reproduce. 4/22/2017

16 Variation and Adaptation
There is variation in nature, and certain heritable variations—called adaptations—increase an individual’s chance of surviving and reproducing. In this population of grasshoppers, heritable variation includes yellow and green body color. Green coloration is an adaptation: Green grasshoppers blend into their environment and so are less visible to predators. 4/22/2017

17 3 Survival of the Fittest
Because their green color serves to camouflage them from predators, green grasshoppers have a higher fitness than yellow grasshoppers. This means that green grasshoppers survive and reproduce more often than do yellow grasshoppers in this environment. 4/22/2017

18 Peppered Moth Simulation Natural Selection
Green grasshoppers become more common than yellow grasshoppers in this population over time because: (1) more grasshoppers are born than can survive, (2) individuals vary in color and color is a heritable trait, and (3) green individuals have a higher fitness in their current environment. 4/22/2017

19 Common Descent Descent with modification refers to the passing on of traits from parent organisms to their offspring. This passing on of traits is known as heredity, and the basic unit of heredity is the gene. Genes hold information about every conceivable aspect of an organism: its growth, development, behavior, appearance, physiology, reproduction. Natural Selection Video 4/22/2017

20 16-4 Evidence of Evolution
Biogeography – study of where organisms live now and where they and their ancestors lived in the past. Closely related but different Distantly related but similar 4/22/2017 Fossilized Dinosaur Heart

21 The Age of Earth and Fossils
Recent Fossil Finds – Refer to Fig 16-13 4/22/2017 Fossilized Dinosaur Heart

22 Comparing Anatomy and Embryology
Homologous Structures Fig 16-14 Analogous Structures Vestigial Structures Fig 16-15 Embryology 4/22/2017 Fossilized Dinosaur Heart

23 Homologous Structures
Refers to the fact that organisms' structures are formed from similar anatomy. Example the wing of a bird, arm of a man, wing of a bat, and flipper of a whale, all appear to be formed from a common set of bones. Implies that these organisms evolved from some common ancestor 4/22/2017

24 Homologous Limb Bones 4/22/2017

25 Analogous Structures Common structure, not common function 4/22/2017

26 Vestigial Structures:
Refers to the fact that organisms have structures which are disused These structures, however, are remnants of structures the organisms used earlier in their evolutionary history. Examples: Hip bones in whales Tail in humans Appendix in humans Legs/hips in snakes 4/22/2017

27 Vestigial Structures 4/22/2017

28 Similarities in Embryological Development
In early embryological development, it appears that embryos "play out" their evolutionary history. Implies that genetically, we have not "forgotten" our evolutionary history, only built upon it. Interactive Activity: Guess the Embryo 4/22/2017

29 How do we know evolution happens?
See how different lines of evidence contribute to our picture of evolution. Learn about the fossil evidence for whales' land-dwelling ancestors. Video #3 PBS Evidence for Evolution Video 4/22/2017

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