Post on 28-Dec-2015
transcript
04/19/232
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.”
04/19/233
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.
04/19/234
•Darwin was a Darwin was a naturalist aboard an naturalist aboard an exploration ship called exploration ship called the the HMS BeagleHMS Beagle..•Collected and Collected and catalogued biological catalogued biological specimens for return to specimens for return to England.England.Charles Darwin’s Book
The Origin of Species/
04/19/235
Section 15-1 Darwin’s Voyage
On a 5 year voyage on the H.M.S.Beagle, Darwin visited several continents and many remote islands. Watch Video#2 PBS
Observations Aboard the Beagle
04/19/236
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
16-2 Ideas That Shaped Darwin’s Thinking
04/19/2310
1. Hutton and Lyell –Refer to Fig. 16-4 and 16-5 Read Pages 454 - 455
2. Jean Baptise Lamark –Refer to Fig 16-6Read page 456
3. Thomas Maltus –Refer to Fig 16-7Read page 457
04/19/2311
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.
04/19/2314
16-3 Darwin Presents His CaseEvolution by Natural SelectionEvolution by Natural Selection
1. Struggle for existence - members of each species compete regularly to obtain food, living space, and other necessities of life.
2. 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
3. Survival of the Fittest - process by which individuals that are better suited to their environment survive and reproduce most successfully; also called natural selection.
4. 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)
04/19/2315
The Struggle for Existence 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 theseoffspring survive to reproduce.
04/19/2316
Variation and Adaptation Variation and Adaptation There is variation in nature, and certain heritable variations—called adaptations—increase an individual’s chance of surviving andreproducing. 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.
04/19/2317
3 Survival of the Fittest 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 andreproduce more often than do yellow grasshoppers in this environment.
04/19/2318
Natural Selection 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 higherfitness in their current environment.
Peppered Moth
Simulation
Common Descent
04/19/2319
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
04/19/2320
16-4 Evidence of Evolution
Fossilized Dinosaur Heart
• BiogeographyBiogeography – study of where organisms live now and where they and their ancestors lived in the past.
– Closely related but different– Distantly related but similar
04/19/2321
The Age of Earth and Fossils
Fossilized Dinosaur Heart
• The Age of Earth
• Recent Fossil Finds – Refer to Fig 16-13
04/19/2322
Comparing Anatomy and Embryology
Fossilized Dinosaur Heart
• Homologous Structures Fig 16-14
–Analogous Structures
–Vestigial Structures Fig 16-15
• Embryology
04/19/2323
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
04/19/2326
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
04/19/2328
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