Evolution

1. Evolution Ch. 15 - 16 By: Gabrielle Carlos Julio Sanchez Rios Austin Paco Kay James Enrique Grant Alex Eduardo Handzel

2. Vocabulary • Evolution:Is the change over time, is the process by which modern organisms have descended from ancient organisms. • Theory: A well-supported testable explanation of phenomena that have occurred in the natural world. • Fossil: Preserved remains of ancient organisms. Ch. 15 Section 1

3. Key Concepts • During his travels, Darwin made numerous observations and collected evidence that led him to propose a revolutionary hypothesis about the way life changes over time. • Darwin observed that the characteristics of many animals and plants varied noticeably among the different islands of the Galápagos. Ch. 15 Section 1

4. Key Concepts • Hutton and Lyell helped scientists recognize that Earth is many millions of years old, and the processes that changed Earth in the past are the same processes that operate in the present. • Lamarck 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. Over time, this process led to change in a species. Ch. 15 Section 2

5. Key Concepts • Malthus reasoned that if the human population continued to grow unchecked, sooner or later there would be insufficient living space and food for everyone. Ch. 15 Section 2

6. Vocabulary • Artificial Selection: In artificial selection, nature provided the variation, and humans selected those variations that they found useful. • Struggle for Existence: Members of each species compete regularly to obtain food, living space, and other necessities of life. • Fitness: The ability of an individual to survive and reproduce in its specific environment. Ch. 15 Section 3

7. Adaptation: Is any inherited characteristic that increases an organism's chance of survival. • Survival of the Fittest: Individuals with characteristics that are not well suited to their environment—that is, with low levels of fitness—either die or leave few offspring. Individuals that are better suited to their environment—that is, with adaptations that enable fitness—survive and reproduce most successfully. • Natural Selection: Results in the changes of inherited traits in a population by survival of the fittest. Ch. 15 Section 3

8. Descent with Modification: Each living species has descended, with changes, from other species over time. • Common Descent: Many animals come from a common ancestor or animal that sprouted into other different animals. • Homologous Structures: Structures that have different mature forms but develop from the same embryonic tissues • Vestigial Organs: Small Traces of homologous structures in different species. Ch. 15 Section 3

9. Key Concepts • In artificial selection, nature provided the variation, and humans selected those variations that they found useful. • Over time, natural selection results in changes in the inherited characteristics of a population. These changes increase a species' fitness in its environment. Ch. 15 Section 3

10. Darwin argued that living things have been evolving on Earth for millions of years. Evidence for this process could be found in the fossil record, the geographical distribution of living species, homologous structures of living organisms, and similarities in early development, or embryology.

11. In genetic terms, evolution is any change in the relative frequency of alleles in a population. • The two main sources of genetic variation are mutations and the genetic shuffling that results from sexual reproduction. • The number of phenotypes produced for a given trait depends on how many genes control the trait. • The number of phenotypes a given trait has is determined by how many genes control the trait. Ch. 16 Section 1- Key Terms

12. A gene pool consists of all genes, including all the different alleles, that are present in a population. • The relative frequency of an allele is the number of times that the allele occurs in a gene pool, compared with the number of times other alleles for the same gene occur. • Among humans, a widow's peak—a downward dip in the center of the hairline—is a single-gene trait. It is controlled by a single gene that has two alleles. • Many traits are controlled by two or more genes and are, therefore, called polygenic traits. Ch. 16 Section 1-Vocabulary

13. Natural selection on single-gene traits can lead to changes in allele frequencies and thus to evolution. • Natural selection can affect the distributions of phenotypes in any of three ways: directional selection, stabilizing selection, or disruptive selection. • Directional selection occurs when individuals at one end of the curve have higher fitness than individuals in the middle or at the other end. • Stabilizing selection takes place when individuals near the center of a curve have higher fitness than individuals at either end. • When individuals at the upper and lower ends of the curve have higher fitness than individuals near the middle, disruptive selection takes place. • In small populations, individuals that carry a particular allele may leave more descendants than other individuals do, just by chance. Over time, a series of chance occurrences of this type can cause an allele to become common in a population. • Five conditions are required to maintain genetic equilibrium from generation to generation: (1) There must be random mating; (2) the population must be very large; and (3) there can be no movement into or out of the population, (4) no mutations, and (5) no natural selection. Ch. 16 Section 2-Key Terms

14. When individuals at one end of the curve have higher fitness than individuals in the middle or at the other end, directional selection takes place. • When individuals near the center of the curve have higher fitness than individuals at either end of the curve, stabilizing selection takes place. • When individuals at the upper and lower ends of the curve have higher fitness than individuals near the middle, disruptive selection takes place • random change in allele frequencies that occurs in small populations is genetic drift. • A situation in which allele frequencies change as a result of the migration of a small subgroup of a population is known as the founder effect • The Hardy-Weinberg principle states that allele frequencies in a population will remain constant unless one or more factors cause those frequencies to change. • The situation in which allele frequencies remain constant is called genetic equilibrium . Ch. 16 Section 2-Vocabulary

15. As new species evolve, populations become reproductively isolated from each other. • Speciation in the Galápagos finches occurred by founding of a new population, geographic isolation, changes in the new population's gene pool, reproductive isolation, and ecological competition. Ch. 16 Section 3-Key Terms

16. But how do these changes lead to the formation of new species, or speciation? • When the members of two populations cannot interbreed and produce fertile offspring, reproductive isolation has occurred. • One type of isolating mechanism, behavioral isolation, occurs when two populations are capable of interbreeding but have differences in courtship rituals or other reproductive strategies that involve behavior. • With geographic isolation, two populations are separated by geographic barriers such as rivers, mountains, or bodies of water. • A third isolating mechanism is temporal isolation, in which two or more species reproduce at different times. Ch. 16 Section 3-Vocabulary

17. http://www.pbs.org/wgbh/evolution/ • http://evolution.berkeley.edu/ • http://www.darwins-theory-of-evolution.com/ Web resources

18. Who went to the Galápagos islands to study variations in the characteristics of animals and plants? • James Hutton, b. Charles Lyell, c. Charles Darwin, d. Thomas Malthus. • Among individuals of a species, differences are referred to as • Natural variation, b. fitness, c. natural selection, d. adaptation. • Tissues and organs animals have but don’t use, but may have used in the past are called what? • Vestigial Organs. • Structures that come from the same tissues and organs in different species from a common ancestor are called what? • Homologous structures. • Difference among individuals of a species are referred to as? • Fitness. • An inherited characteristic that inscreases an organism’s ability to survive and reproduce is a what? • Adaptation. • True or false. Artificial Selection is the process by which nature chooses the fittest to survive in their environment through characteristics. • False. It is Natural Selection. Questions

19. True or false. An animal in the past that is related to two present day animals is a common ancestor. • True. • An animals Fitness is a result of: A) Common Descent B) Adaptations C) Vestigial Organs D) Mr. Umlor • The answer is B (or D) • Preserved remains of ancient organisms are called what? • Fossils. • Random change in allele frequencies is called what? • Genetic Drift. • If in a population, the middle sized organism is best fit, what would eventually happen? • Stabilizing selection. • True or false. The combined getentic information of all members of a particular population forms a gene pool. • True. • The success of an organisms survival and reproduction is its what? • Fitness. Questions

20. True or False. Directional selection is when individuals at one end of the curve are equal to the other extreme. • False. It is disruptive selection. • A random change in a small populations allele frequency is called hwat? • Variation. • If a group of an individuals of the same species can interbreed, that makes it a _____? • A population. • Once two animals of a population cannot interbreed anymore, what two things occur? • Reproductive isolation, a new species is formed. • True or false. temporal isolationis when two or more species reproduce at different times. • True. • Is Mr. Umlor cool? A) Yes. B) Maybe. C) NO?! D) How does this relate to biology? Questions