Natural Selection PDF (Edgenuity)

Warm-Up ? Lesson Question Natural Selection How does natural selection affect the evolution of a species? Lesson Goals Explore how natural selection affects the evolution of a species. Identify the conditions required for natural selection. W 2K Identify how Examine ways in which genetic variation c...

Warm-Up ? Lesson Question Natural Selection How does natural selection affect the evolution of a species? Lesson Goals Explore how natural selection affects the evolution of a species. Identify the conditions required for natural selection. W 2K Identify how Examine ways in which genetic variation contributes to natural selection. environmental Describe factors that contribute to the extinction of a species. factors contribute to natural selection. Words to Know Fill in this table as you work through the lesson. You may also use the glossary to help you. a behavior or trait that increases the ability of an organism to adaptation survive and/or reproduce disappearance extinction the total predator an organism that variation the inherited kills another for food differences between individuals of the same species © Edgenuity, Inc. of all members of a species 1 Warm-Up Natural Selection Evolution Evolution is the process of change in a Organisms develop favorable their environment. traits population over time. that make them better suited for Natural selection occurs when organisms with the traits most suited to the environment survive and © Edgenuity, Inc. reproduce 2. Instruction Natural Selection Slide 2 Natural Selection Natural selection occurs when: variation populations have genetic the environment organisms survive 4. changes. with traits most suited to the environment and reproduce. Overproduction of Offspring Species tend to produce more offspring than can survive adulthood Many offspring will die before they reach. and can reproduce. The organisms that do survive pass on their traits to their offspring. Variation The organisms in a population have a variety of traits. These traits are inherited © Edgenuity, Inc. randomly 3. Instruction Natural Selection Slide 4 Favorable Adaptations An adaptation is a behavior ability or trait that increases the of an organism to survive and/or reproduce. When the environment changes , the organisms that have adaptations best suited for the new environment survive and reproduce. Favorable adaptations are passed on to than unfavorable adaptations. offspring in larger numbers Favorable Adaptations Increase generations Favorable adaptations build up in a population over many This may lead to a new 7 species. Genetic Variation Genetic variation is caused by random organisms. A mutation results in different alleles for a adaptations These different alleles will cause or unfavorable. © Edgenuity, Inc. mutations 4 in the genes of gene. that may be favorable. Instruction Natural Selection Slide 7 Environmental Change Changes in the environment can result in one adaptation being selected over another. evolves Over time, the population. The number of individuals with the favorable adaptation increases. The number of individuals with the unfavorable adaptation decreases 9. Environmental Change and Natural Selection The peppered to the moth Industrial population in Manchester, England, changed due Revolution. It changed again when the Industrial Revolution was over and the air became © Edgenuity, Inc. cleaner. 5 Instruction Natural Selection Slide 11 Extinction If an environment changes and a species cannot will occur. More individuals fighting over the same The introduction of new predators adapt , extinction resources into an area Extinction EXAMPLES OF EXTINCTION The occurrence of a natural disaster The loss of the environment in which an organism’s © Edgenuity, Inc. 6 needs are met Summary ? Natural Selection Lesson Question How does natural selection affect the evolution of a species? Answer (Sample answer) Changes in the environment can result in one adaptation being selected over another, which causes the population to evolve. If the environment changes, the population will change because different adaptations will be selected by nature. Slide 2 Review: Key Concepts Natural selection occurs when organisms with the traits most suited to the environment survive and reproduce. There are four conditions required for natural selection: offspring Overproduction of Variation Natural selection of favorable adaptations Favorable adaptations building in a population © Edgenuity, Inc. 7 Summary Natural Selection Slide 2 Review: Key Concepts random Genetic variation is caused by of organisms. mutations in the genes This results in different alleles that cause adaptations, which may be favorable or unfavorable depending on the environment. Changes in the environment can result in one adaptation being selected over another, which causes the population to evolve. If the environment changes and a population is no longer able to survive, it will become extinct. Use this space to write any questions or thoughts about this lesson. © Edgenuity, Inc. 8