Chapter 22: Descent with Modification Macroevolution vs. Microevolution Plato • No evolution; we are all ideally created Aristotle • Chain of being Carolus Linnaeus (1707-1778) • Natural Theology • Classification Georges Cuvier (1769-1832) • Paleontology • Catastrophism James Hutton (1726-1797) • Gradualism Charles Lyell (1797-1875) • Uniformitarianism Jean Baptiste Lamarck (1744-1829) • Looked at fossils, saw gradual change over time • Inheritance of acquired characteristics • Adaptation Charles Darwin (1809-1882) • Natural Selection Alfred Wallace • Natural Selection Natural Selection: Observations and Inferences • Observation #1: All species have such great potential fertility that their population size would increase exponentially if all individuals that were born reproduced successfully. • Observation #2: Populations tend to remain stable in size, except for seasonal fluctuations. • Observation #3: Environmental resources are limited. • Inference #1: Production of more individuals than the environment can support leads to a struggle for existence among individuals of a population, with only a fraction of offspring surviving each generation. • Observation #4: Individuals of a population vary extensively in their characteristics; no two individuals are exactly alike. • Observation #5: Much of this variation is heritable. • Inference #2: Survival in the struggle for existence is not random, but depends in part on the hereditary constitution of the individuals. Those individuals whose inherited traits best fit them to their environment are likely to leave more offspring than less fit individuals. • Inference #3: This unequal ability of individuals to survive and reproduce will lead to a gradual change in a population, with favorable characteristics accumulating over generations. Name: _____________________________ Date: __________ Period: __________ Evolution and Natural Selection Charles Darwin was born on February 12, 1809. Charles Darwin is best known for writing the book, ____________________________ (1859), in which he explained his theory of Natural _________________. Several individuals provided information that helped Darwin come up with his ideas on Natural Selection. James Hutton (1726-1797) and Charles Lyell (1797-1875) Both were geologists. The earth is very, very, very __________. Processes that have changed the earth over time are the same as those that act upon the Earth today. Jean Baptiste Lamarck (1744-1829) Coined the term Biology (1802) Looked at fossils. Inheritance of _____________ characteristics. Idea of ______________________. Thomas Malthus (1766-1834) Earth’s population is growing very _________. If the population continues to grow unchecked, sooner or later there will not be enough ______________ or ______________ for everyone. Darwin’s Theory of Natural Selection In 1831, Darwin set sail on the H.M.S. Beagle to sail around the world. Darwin developed his theory of Natural Selection based on observations made on this trip. Darwin’s friend Alfred Wallace also generated ideas on Natural Selection. They both published their work at the same time. The Theory of Natural Selection • Organisms produce ___________ individuals than can possibly survive. • Many die, others will live and reproduce. • The organisms that live to reproduce are the ones that have traits making them most _____________ to their environment. • Over time, favorable traits will be seen more often, as genes for those traits are more likely to be passed on to the next generation. • Natural Selection is also referred to as: ____________ of the ________________. • The product of Natural Selection is _________________. • Adaptations are: ________________ characteristics that increase an organism’s chance of survival. Examples of Evolution and Natural Selection Camouflage Guppy Variation Insects Disease Resistance Antibiotic Resistance Mimicry Examples of Artificial Selection Dogs Vegetables Types of Selection Directional Selection o Selects for individuals at one extreme of a characteristic. o During a drought, finches with large beaks are more likely to survive. Disruptive Selection o Individuals at both the upper and lower extreme of a characteristic are favored. o When large/hard seeds or small/soft seeds are available, finches with either large or small beaks survive the best. Stabilizing Selection o Individuals with intermediate/average levels of a trait are favored. o Birth Weight. Sexual Selection o Females select males that are stronger and most healthy. o Often, physical traits indicate health of an organism. Vocabulary Words 1. Evolution: change over time in populations of living things. 2. Natural Variation: differences among individuals of a species. 3. Fitness: the ability of an individual to survive and reproduce in its specific environment. 4. Adaptation: any inherited characteristic that increases an organism’s chance of survival. 5. Survival of the Fittest: Individuals that are better suited to their environment—that is, with high levels of fitness—are more likely to survive and reproduce. 6. Natural Selection: Individuals that are better suited to their environment—that is, with high levels of fitness—are more likely to survive and reproduce. 7. Descent with Modification: The principle that each living species has descended, with changes, from other species over time. 8. Homologous Structures: Structures that have different mature forms in different organisms but develop from the same embryonic tissues/have the same evolutionary origin. Often result from Divergent Evolution. 9. Analogous Structures: Structures that are similar in function but have different evolutionary origins. The result of Convergent Evolution. .