TheTheoryofEvolution

= //**The Theory of Evolution**// = __**Confused about Evolution? Watch this video for some clarification and some evidence.**__ (Link will open in a new window) ü You will analyze the theory of evolution ü You will compare and contrast the processes of evolution Evolution is the key concept for understanding biology. Evolution explains the diversity of species and predicts changes. ** Section 1- Natural Selection and the Evidence for Evolution ** **Review Vocabulary** ü Evolution! the changes in populations over time ** New Vocabulary ** ü Artificial Selection :) ü Natural Selection!!
 * What You’ll Learn **
 * Why It’s Important **

ü Camouflage(:



ü Homologous Structure :D

ü Analogous Structure ü Vestigal Structure!



ü Embryo!!!

1. ** Charles Darwin and Natural Selection ** Evolution is the change in population over time. Learning about evolution will help make understanding Biology easier.evolution over time! · ** Fossils shape ideas about evolution ** Since the eighteenth century, scientists have been using fossils in their research. They began wondering how fossils were formed and why there were extinct species. Biologists began thinking that species evolved or changed overtime. Charles Darwin developed the first theory of this type. = · ** Darwin ** ** on HMS Beagle**= Darwin was 22 when he took a job as a naturalist in 1831. He worked on the English ship, HMS Beagle. The Beagle sailed around the world in 5 years, not 80 days. At every port, Darwin collected biological and fossil specimens. These studies made Darwin curious about relationships between species and became the foundation for his theory on evolution. · ** Darwin **** in the Galapagos (guh LAH puh gus) ** Darwin visited the Galápagos islands, a group of small islands near the equator off the west coast of South America, and made many important discoveries. He found many species unique to the islands yet similar to species elsewhere. This led to Darwin considering the possibility of species changing overtime. · ** Darwin **** continues his studies ** For the next two decades, Darwin tried very hard to find evidence for his theory. English economist, Thomas Malthus proposed an idea that the human population would grow faster than the food supply. Darwin's tree of life ü Why do you think Charles Darwin’s studies were so important? ü What evidence is there that the theory of evolution is correct? In your opinion, is there enough evidence to believe that the theory is true? ü Can you think of an example of a vestigial structure? How about a homologous structure? An analogous structure? ü Can you think of an example of an animal that uses mimicry? How about one that uses camouflage? How does this help them survive?
 * Section 1 Review Questions: **

*Additional Link: To help you better understand natural selection and camouflage go to the following site and play the simulation game about peppered moths. []


 * __Section 2-__ Mechanisms of Evolution **

Gene DNA segment that controls protein production and the cell cycle. ü Gene Pool ü allelic frequency ü Genetic Equilibrium ü Genetic Drift ü Stabilizing Selection. ü Directional Selection ü Disruptive Selection ü Speciation ü Geographic Isolation ü Polyploid ü Punctuated equilibrium ü Adaptive Radiation ü Divergent Evolution ü Convergent Evolution
 * Review Vocabulary **
 * New Vocabulary **

1. ** Population Genetics and Evolution ** When Darwin first created the theory of evolution, he didn’t know about genes. Now that we have more knowledge about genetics, scientists have been able to modify the theory accordingly. In the beginning, genetic information was used to explain variation in individuals of a population, but studies of the behavior of genes in populations developed into population genetics. The modern theory of evolution is rooted in population genetics and other studies.

· ** Populations, not individuals, evolve ** If an organism has a feature, a phenotype, that does not adapt to the environment, the organism may be unable to survive and reproduce. Within its lifetime, it cannot evolve a new phenotype by natural selection in response to its environment. Natural selection acts on the range of phenotypes in a population. All of the genes of the population’s individuals make up the population’s genes. Evolution happens when a population’s genes and their frequencies change over time. All of the alleles of the population’s genes together is called a //gene pool//. The percentage of any specific allele in the gene pool is called the //allelic frequency//. When the frequency of alleles stays the same over generations it is called //genetic equilibrium.// Populations Evolve

· ** Changes in genetic equilibrium ** A population that is in genetic equilibrium is not evolving. Any factor that affects the genes in the gene pool can change allelic frequencies, disrupting a population’s genetic equilibrium, which results in evolution. One mechanism for genetic change is mutation. Mutations can be caused by the environment or they can occur by chance. Many mutations are lethal. Lethal mutations are quickly eliminated. Occasionally a mutation will be useful and it will become part of the gene pool through natural selection.

Other mechanisms for genetic change include //genetic drift// (the alteration of allelic frequencies by chance events) and the movement of individuals in and out of a population. Genetic drift greatly affects small populations. · ** Natural Selection acts on variations ** Natural Selection is a big mechanism for genetic change in populations. It occurs when organisms with favorable variations survive, reproduce, and pass on their variations. There are three kinds of natural selection. 1. ** Stabilizing selection- ** natural selection that favors average individuals in a population.
 * Ex: ** Average size bugs are favored because the larger are easier to find and more get eaten, while small bugs have difficulty finding food.

2. ** Directional selection- ** natural selection that favors one of the extreme variations of a trait.
 * Ex: ** Giraffes with long necks might be favored because they can reach the food on the tall trees, while neither the average nor short necked giraffes can reach it.

3. ** Disruptive selection- ** natural selection that favors both extreme variations of a trait. 2. ** The Evolution of Species ** A species is a group of organisms that look alike and can produce fertile offspring. //Speciation// is the evolution of new species. This occurs when members of similar populations do not interbreed to produce fertile offspring. · ** Physical barriers can prevent interbreeding ** // Geographic Isolation // is when a physical barrier divides a population. This isolation can cause species to evolve. These barriers include lava from volcanoes, sea-level changes, and other environmental factors.
 * Ex: ** Dark and light colored moths are favored over moths that have a color that is in between. The dark have camouflage in dark places, light are hidden in light places, but the in between color can be seen in both.



· ** Reproductive isolation can result in speciation ** // Reproductive Isolation // happens when formerly interbreeding organisms can no longer mate and produce fertile offspring. There are two types of reproductive isolation. One type is when the genetic material of the population becomes so different that fertilization is impossible. This is often caused by geographic isolation. The second type is behavioral. · ** A change in chromosome numbers and speciation ** // Polyploid // is any individual or species with a multiple of the normal set of chromosomes. Polyploids can cause speciation to occur. Mistakes during mitosis and meiosis cause polyploids to occur. The developing zygotes may not develop normally. · ** Speciation Rates ** Polyploid speciation takes only one generation, but other types take longer. //Gradualism// is the idea of species originating through a gradual change of adaptations. //Punctuated Equilibrium// is another idea proposed Niles Eldredge and Stephen J. Gould in 1972. This theory argues that speciation occurs rather quickly with long periods of genetic equilibrium in between. Biologists tend to agree with both hypotheses. 3. ** Patterns of Evolution ** Throughout time biologists have observed different patterns of evolution which support the fact that natural selection is an important part of evolution. · ** Diversity in new environments ** // Adaptive radiation // is the result of an ancestral species that evolves into many different species to fit a number of diverse habitats. Adaptive radiation is a type of //divergent evolution//. Divergent evolution is the pattern of evolution where species that used to be similar to an ancestral species become increasingly distinct. This happens when populations adapt to different environmental conditions.



· ** Different species can look alike ** // Convergent evolution // is a pattern of evolution where distantly related organisms evolve to have similar traits. This occurs when unrelated species occupy similar environments in different places in the world. ü What are the three types of natural selection? How are they different? Can you think of examples for each? ü What are the affects of geographic and reproductive isolation? How do they cause speciation? ü What characteristics does a population need to have in order for rapid evolution to occur? ü What is the difference between gradualism and punctuated equilibrium? Why do you think that biologists accept both ideas as being correct?
 * Section 2 Review Questions: **

** CHAPTER 15 **
 * V **** O **** C **** A **** B **** Quiz **** ! **

// SECTION 1: // 1. The gradual change in species through adaptation over time is called __.__ 2. is the process of breeding organisms with specific traits in order to produce offspring with identical traits. 3. Structures that do not have a common evolutionary origin but are similar in function are called __.__ 4. is the structural adaptation that enables one species to resemble another species. It may provide protection from predators or other advantages. 5. When organisms with favorable variations survive, reproduce, and pass on their variations it is called __ . __ 6. is the structural adaptation that allows organisms to blend into their surroundings protecting them from predators. 7. When both plants and animals are in their earliest stage of growth and development they are called __.__ Differences and similarities between these can provide evidence for evolution. 8. A is a structure with common evolutionary origins, has similar arrangements, or function, or both. These structures are evidence for evolution. 9. A structure that provides evidence for evolution because it does not serve a purpose for the modern day organism, but might have served its purpose for the organisms ancestors is called a __.__
 * Insert the correct vocabulary word in to the space in the sentence. All of the words are in the word bank below. **

// SECTION 2: // 10. When all of the alleles of a population’s genes are together it is called a __.__ 11. When the frequency of alleles stays the same over generations it is called __.__ 12. The percentage of any specific allele in the gene pool is called the __.__ 13. The alteration of allelic frequencies by chance events is called __.__ 14. Natural selection that favors one of the extreme variations of a trait is __.__ 15. Natural selection that favors average individuals in a population is __.__ 16. Natural selection that favors both extreme variations of a trait is __.__ 17. is when a physical barrier divides a population. 18. is the evolution of new species. 19. is any individual or species with a multiple of the normal set of chromosomes. They can cause speciation to occur. 20. happens when formerly interbreeding organisms can no longer mate and produce fertile offspring. 21. is the result of an ancestral species that evolves into many different species to fit a number of diverse habitats. 22. is the idea of species originating through a gradual change of adaptations. 23. is an idea proposed by Niles Eldredge and Stephen J. Gould in 1972. This theory argues that speciation occurs rather quickly with long periods of genetic equilibrium in between. 24. is the pattern of evolution where species that used to be similar to an ancestral species become increasingly distinct. 25. is a pattern of evolution where distantly related organisms evolve to have similar traits.

Artificial selection speciation polyploid Natural selection gradualism adaptive radiation Camouflage genetic drift Mimicry gene pool Embryo allelic frequency Vestigial structure genetic equilibrium Evolution geographic isolation Homologous structure reproductive isolation Analogous structure stabilizing selection Directional selection punctuated equilibrium Disruptive selection divergent evolution Convergent evolution ||
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