Natural Selection Note Packet PDF

Unit 7: Natural Selection​ ​ Name: _________________________ Evolution as change in the heritable characteristics of a population ​ Define evolution. ​ Distinguish between Lamarckism and Darwinian evolution. ​ Outline evolutio...

Unit 7: Natural Selection​ ​ Name: _________________________ Evolution as change in the heritable characteristics of a population ​ Define evolution. ​ Distinguish between Lamarckism and Darwinian evolution. ​ Outline evolution via natural selection as a paradigm shift in biology. Natural selection as the mechanism driving evolutionary change ​ Define natural selection. ​ Outline the observations and inferences that lead to the development of the theory of evolution by natural selection. ​ Outline the theory of evolution by natural selection as an example of inductive reasoning. ​ Outline the theory of evolution by natural selection as an example of the correspondence, coherence and pragmatic theories of truth. ​ State that natural selection has operated continuously over billions of years, resulting in the biodiversity of life. Requirement that traits are heritable for evolutionary change to occur ​ Distinguish between heritable and acquired characteristics. ​ Explain why only heritable characteristics can be acted upon by natural selection. Roles of mutation and sexual reproduction in generating the variation on which natural selection acts ​ Explain why natural selection can only function if there is variation in a species. ​ Outline sources of genetic variation (mutation, meiosis and sexual reproduction). ​ Compare variation that results from mutation to that generated from sexual reproduction. Mutation as a source of genetic variation ​ State the source of new alleles of a gene. ​ State that gene mutation is the original source of all genetic variation. ​ Distinguish between beneficial, neutral and harmful gene mutations. Overproduction of offspring and competition for resources as factors that promote natural selection ​ State that species have the ability to produce more offspring than the environment can support. ​ Use an example to illustrate the potential for overproduction of offspring in a population. ​ State two evolutionary benefits of overproduction of offspring. ​ Describe competition for resources as a consequence of overproduction of offspring. ​ Define carrying capacity ​ List examples of resources that may limit population size. ​ Compare direct and indirect competition. Abiotic factors as selection pressures ​ Define selective pressure and density-independent. ​ State example biotic and abiotic selective pressures. ​ Outline how a selective pressure acts on the variation in a population. Sexual selection as a selection pressure in animal species ​ Outline the two major mechanisms of sexual selection in evolution of courtship behavior and anatomical features. ​ Outline examples of sexual selection, including for color, size, and courtship behaviors. Differences between individuals in adaptation, survival and reproduction as the basis for natural selection ​ Define adaptation and fitness. ​ Explain the effect of the selective pressure on the more and less adapted individuals in a population. ​ Explain adaptation as a consequence of natural selection. Antibiotics as chemicals that block processes occurring in bacteria but not in eukaryotic cells ​ Outline the natural function of antibiotics when secreted from saprotrophic fungi. ​ Outline the function of antibiotics when used in medical treatment. ​ State why antibiotics fail to control viral infections. Evolution of resistance to several antibiotics in strains of pathogenic bacteria ​ Describe how natural selection leads to the development of antibiotic resistance in bacteria. ​ Discuss the medical consequences of evolution of multidrug antibiotic resistance. ​ Outline techniques for discovering new sources of antibiotic chemicals. Evidence for evolution from selective breeding of domesticated animals and crop plants Artificial selection by deliberate choice of traits ​ Define artificial selection. ​ List reasons why humans have selectively bred domesticated animals and crop plants. ​ Outline how selective breeding can lead to rapid evolutionary change. ​ Outline the mechanism of artificial selection in evolution of crop plants and domestic animals. ​ Describe an example of artificial selection of a crop plant or domestic animal. Evolution as a consequence of climate change ​ Outline impact of climate change as a selection pressure. ​ Explain changes in the colors variants of the tawny owl as an example of evolution in response to climate change. Modeling of sexual and natural selection based on experimental control of selection pressures ​ Outline the selective pressures for and against coloration in guppies. ​ Summarize John Endler’s experiments with guppies which demonstrate selection for and against coloration in different habitats. ​ Explain what models are and their purposes in science. 1 Evolution as change in the heritable characteristics of a population Evolution is the: Lamarckism Darwinism Use and disuse: Natural selection: ​ Inheritance of acquired characteristics: ​ ​ ​ 2 Lamarck's proposal of inheritance of acquired characteristics as the mechanism of evolution was superseded by Darwin’s argument for evolution by natural selection. We now understand that physical changes that occur during an organism's lifetime are not passed to offspring. This is because: This is an example of a paradigm shift in science, which is …. Natural selection as the mechanism driving evolutionary change Darwin based the idea of natural selection on his and others’ observations and inferences about the natural world. 3 Theory of Evolution by Natural Selection The theory of evolution by natural selection is based on observations. Theories developed from observations are an example of…. Natural selection adheres to the correspondence, coherence and pragmatic theories of truth. ​ Correspondence theory: natural selection is true because it accurately …. ​ Coherence theory: natural selection is true because it coherently fits within a … ​ Pragmatic theory: natural selection is true because it has …. Requirement that traits are heritable for evolutionary change to occur Traits must be heritable for natural selection to affect them. While traits that are not heritable may affect survival and reproduction of an individual, since they are not passed to offspring they do not change the characteristics of the population over time. Heritable Characteristics Acquired Characteristics Heritable characteristics are those that can be Traits acquired during an individual’s lifetime are not passed down from parent to offspring. subject to natural selection because they are not passed onto offspring. ​ Heritable traits are … ​ Many acquired characteristics … ​ In sexually reproducing species, only the … ​ Changes to DNA that do occur within the lifetime are typically … 4 Roles of mutation and sexual reproduction in generating the variation on which natural selection acts Variation is a defining feature of life. Genetic variation within a species can result from: Mutation Gene Flow Meiosis Sexual Reproduction Whereas mutation as a source of variation occurs at random, the probability of a variation being passed on to the next generation is not random if it impacts the survival and reproductive capabilities of that organism. ​ Variations that promote survival and reproduction will be … ​ Variations that reduce survival and reproduction will be... 5 Mutation as a source of genetic variation Genetic variation in a population of organisms enables some organisms to survive better than others in the environment in which they live: Beneficial Mutations Harmful Mutations Neutral Mutations Some mutations cause a change in Some mutations cause a change in Some mutations have …. DNA that results in a new version DNA that results in a protein of a protein that… that… If the mutation______________ Neutral mutations may: an organism’s chances of surviving If the mutation______________ or reproducing, it will be an organism’s chances of surviving ​ Be the result of a __________________________ or reproducing, it will be _____________________, in the population, and its __________________________ in which the change to the frequency in the population will in the population, and its DNA does not affect the… ______________ as a result of frequency in the population will natural selection. ______________ as a result of natural selection. ​ Affect traits that do not Example: affect the…. Example: Overproduction of offspring and competition for resources as factors that promote natural selection Living organisms vary in the number of offspring they produce, however there is an overall trend for … Evolutionary benefits to the overproduction of offspring: 1.​ 2.​ 6  Overproduction of offspring leads to the potential for Most natural populations exhibit “logistic growth” in “exponential growth” of a population in which it which there is rapid growth at first when the increases in size each year. population is small and resources are plentiful, but the growth rate slows as the population size increases and resources begin to be in short supply. In natural populations, exponential growth can not The number of individuals will stabilize at the continue indefinitely because … “carrying capacity” which is the … Competition is a result of overproduction of offspring and limited resources.. Competition for resources is one of the ways natural selection can act; not every individual will obtain enough resources to survive and reproduce. Direct Competition Indirect Competition 7 Abiotic factors as selection pressures Selection pressures are …. Selection pressures can be … Selection pressures are the …. Biotic Selection Pressures Abiotic Selection Pressures Abiotic selection pressures are often density independent, which means … Sexual selection as a selection pressure in animal species Sexual selection is: There are two major forms: One biological sex chooses which individual of the Competition between members of the same sex for other sex to mate with access to members of the opposite sex Examples: Examples: Sexual selection can result in the development of…. 8 Differences between individuals in adaptation, survival and reproduction as the basis for natural selection Fitness is a measure of … Individuals are more or less “fit” which means they are more or less … ​ Less fit individuals have … ​ More fit individuals have … Variations that promote survival and/or reproduction in the face of the selection pressure will be passed on to the next generation during reproduction at a higher frequency than variations that reduce survival and/or reproduction. Over generations, the frequency of the selected variation will … The heritable features of the population will have changed over time, so… The pace of change in a population due to natural selection can vary depending on the strength of the selection pressure. ​ Rapid evolution will occur if: ​ Gradual evolution will occur if: Adaptations are forms that correspond to function. The differential survival and reproduction results in a population that is adapted to its environment because individuals have adaptations that allow them to survive and reproduce. 9 Antibiotics as chemicals that block processes occurring in bacteria but not in eukaryotic cells A pathogen is: A broad range of disease-causing organisms can infect humans: Depending on what pathogen is making you sick, you may or not be given ANTIBIOTICS as a treatment. Antibiotics are: Antibiotics will only work on bacteria because they: For example, antibiotics can specifically target prokaryotic cell: ​ ​ ​ ​ ​ Naturally Occuring Antibiotics Saprotrophs are: Saprotrophic fungi naturally produce antibiotics. By synthesizing and secreting antibiotics, the fungi are able to: Antibiotics do not Target Viruses. Viruses are nonliving and do not have these structures or metabolic pathways: ​ ​ ​ Misuse of antibiotics to treat viral infections contributes to the evolution of antibiotic resistance in bacteria. 10 Evolution of resistance to several antibiotics in strains of pathogenic bacteria Since their discovery as chemicals that kill bacteria, antibiotics have been used for: ​ ​ ​ ​ Resistance to Antibiotics is the Result of Natural Selection Population Overproduction Variation in heritable traits A selection pressure that affects survival and/or reproduction of individuals in a population Differential survival and/or reproduction of individuals in response to the selection pressure A change in the frequency of the heritable trait in the population over time 11 Careful careful use of antibiotics is necessary to slow the emergence of multiresistant bacteria. Multidrug-resistant organisms are: There is an urgent need for new antibiotics because bacteria are constantly evolving to resist the drugs used to fight them. Technological advancement begets discovery. The development of new techniques can lead to new avenues of research and new discoveries. For example: ​ The technique of searching chemical libraries is yielding new antibiotics. ​ Machine learning is used to predict potential new antibiotics. 12 Evidence for evolution from selective breeding of domesticated animals and crop plants and Artificial selection by deliberate choice of traits Artificial selection occurs when: ​ ​ ​ ​ ​ ​ ​ Artificial selection demonstrates that evolution occurs. Because the selection pressure imposed by humans is often more intense than that occurring in nature… Example Sketch Selected Trait(s) Plant Animal 13 Evolution as a consequence of climate change Climate change is a strong selection pressure. Climate change can impact organisms in a number of ways, including: ​ Access to resources: ​ Phenotypic mismatches: ​ Disrupted phenology: Overproduction of offspring Variation in heritable traits A selection pressure that affects survival and/or reproduction of individuals in a population Differential survival and/or reproduction of individuals in response to the selection pressure A change in the frequency of the heritable trait in the population over time 14 Modeling of sexual and natural selection based on experimental control of selection pressures Evolutionary biologist John Endler studied wild guppies (Poecilia wingei) in Trinidad where they live in small pools associated with mountain streams. Selection Pressures on Guppy Color Variation Drab​ ​ ​ ​ ​ ​ ​ Average​ ​ ​ ​ ​ Flashy What is the impact of predators on the number of spots on male guppies? Use natural selection to explain the results. What is the impact of female preference on the number of spots on male guppies? Use sexual selection to explain the results. Why do different predators affect the average number of spots on fish in the population? Predict what happened when Endler moved fish from a habitat with cichlid predators to a habitat in which there were none. 15 Why are models used in science? ​ ​ ​ ​ ​ Types of Models: 1.​ 2.​ 3.​ 4.​ 5.​ 6.​ Limitations of Models. ​ No model can possibly explain every detail of a phenomena. A good model must be able to represent as many characteristics of reality as possible, but also be as simple as possible. ​ Like anything in science, models… ​ Models can only be as accurate as… ​ If models tested against experiments or data from observations prove inadequate, they may be … 16