2. Learning Targets for Evolution 8.1 I can define evolution and use the definition to predict where modern organisms have come from. 8.2 I can recognize that evolution requires a long period of time to occur. 8.3 I can compare artificial selection to natural selection and am able to identify each from examples. 8.4 I can identify the two major sources of variation in organisms that reproduce sexually. 8.5 I can explain why genetic variation within a population is essential for change over time. 8.6 I can list examples of challenges that organisms face in their struggle for existence. 8.7 I can explain why organisms compete with one another in order to survive. 8.8 I can define the term adaptation.
3. Learning Targets Continued… 8.9 I can predict what will happen when organism’s adaptations are more suited to their environment. 8.10 I can describe the difference between an individual and a population and state which is affected by evolution. 8.11 I can differentiate between the concept of an adaptation and the process of evolution. 8.12 I can predict how an adaptation will change in frequency within the population over time. 8.13. I can use graphical data to describe how the frequency of a particular trait will change in response to different natural selection pressures. 8.14 I can explain convergence in terms of how unrelated species respond to similar environmental pressures. 8.15 I can use the process of natural selection to explain how divergence and adaptive radiation lead to diverse populations from one common ancestor. 8.16 I can use co-evolution to explain what will happen to two organisms that are closely connected to each other
5. Important Terms Evolution Artificial selection Natural selection Variation Competition Adaptation Convergence Divergence Adaptive radiation Co-evolution Theory
6. What is a Theory? Theory- a well-substantiated explanation of some aspect of the natural world that can incorporate facts, laws, inferences, and tested hypotheses
7. Law- a descriptive generalization about how some aspect of the natural world behaves under stated circumstances and that carries the weight of scientific evidence Fact-an observation that has been repeatedly confirmed Hypothesis- a testable statement about the natural world Belief- a psychological state in which a person holds a premise (or statement) to be true.
8. Evolution by Natural Selection is a theory Evolution (or change in organisms over time) is a scientific theory; it is a well-substantiated explanation of an aspect of the natural world that incorporates facts (observable phenomena) such as virus and bacterial adaptations, inferences (geological processes have always been happening at a constant rate in the history of the Earth), and tested hypotheses (evolutionary relationships echoed in DNA analysis).
9. Age of the Earth Earth is about 4.5 billion years old Geologists confirmed this approximate date through determining the age of rock formations and the time it would take for them to form
11. Time is important: If weathering and other geological processes have been happening at the same rate for a very long time (or always) then the Earth must be several billion years old to account for the formations. Other ways we know: Chemical analysis of ice cores radio active fluorine
12. Evolution Change in organisms over time These changes are seen in populations not in individuals
13. Charles Darwin On the Origin of Species in 1859. Darwin supplied evidence that evolution has occurred. He also explained his ideas about how (mechanism) evolution occurs.
14. Darwin’s theory was based on artificial selection. In artificial selection, nature provided the variation, and humans selected those variations that they found useful. For example, animal breeders used only the largest hogs, fastest horses, or cows that produced the most milk for breeding.
15. Artificial Selection Natural Selection Variation in traits exists Breeder selects favorable traits in organism Breeder mates animals with the favorable traits more than other organisms Desired traits become more common in population Variation in traits exists Nature “selects” favorable traits in organism because some of these trait give a reproductive or survival advantage Organisms with favorable traits survive better and have more offspring Traits that give a reproductive/survival advantage become more common in population
16. Why do both forms of selection require variation?
17. Sources of variation Genetic Shuffling in Anaphase I of meiosis Mutation to DNA passed down to offspring (very rare!)
19. Competition Competition is a struggle for limited resources in which there can only be one or a few “winners” On Earth we have a finite number of resources; there are many more organisms than resources. A struggle for survival results, the organisms that get the resources will live and pass on their genes to the next generation. Besides limited resources; what are some other challenges organisms must face to survive and reproduce?
20. Adaptations Traits that provide some type of advantage to organisms in the struggle for survival are called adaptations. There are recognizable patterns to the way organisms adapt
21. Predict what will happen to a bunny population with a brown fur mutation in an equatorial environment.
