Adj natural selection

Evolution by Natural Selection,[object Object],Hour 2, 2-23-2011,[object Object]

Learning Targets for Evolution,[object Object],8.1 I can define evolution and use the definition to predict where modern organisms have come from.,[object Object],8.2 I can recognize that evolution requires a long period of time to occur. ,[object Object],8.3 I can compare artificial selection to natural selection and am able to identify each from examples.,[object Object],8.4 I can identify the two major sources of variation in organisms that reproduce sexually.,[object Object],8.5 I can explain why genetic variation within a population is essential for change over time.,[object Object],8.6 I can list examples of challenges that organisms face in their struggle for existence.,[object Object],8.7 I can explain why organisms compete with one another in order to survive.,[object Object],8.8 I can define the term adaptation.,[object Object]

Learning Targets Continued…,[object Object],8.9 I can predict what will happen when organism’s adaptations are more suited to their environment.,[object Object],8.10 I can describe the difference between an individual and a population and state which is affected by evolution.,[object Object], 8.11 I can differentiate between the concept of an adaptation and the process of evolution.,[object Object], 8.12 I can predict how an adaptation will change in frequency within the population over time.,[object Object],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. ,[object Object],8.14 I can explain convergence in terms of how unrelated species respond to similar environmental pressures. ,[object Object],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.,[object Object], 8.16 I can use co-evolution to explain what will happen to two organisms that are closely connected to each other ,[object Object]

Why should we study evolution?,[object Object]

Important Terms,[object Object],Evolution ,[object Object],Artificial selection,[object Object],Natural selection,[object Object],Variation,[object Object],Competition,[object Object],Adaptation,[object Object],Convergence,[object Object],Divergence,[object Object],Adaptive radiation,[object Object],Co-evolution,[object Object],Theory,[object Object]

What is a Theory?,[object Object],Theory- a well-substantiated explanation of some aspect of the natural world that can incorporate facts, laws, inferences, and tested hypotheses,[object Object]

Law- a descriptive generalization about how some aspect of the natural world behaves under stated circumstances and that carries the weight of scientific evidence,[object Object],Fact-an observation that has been repeatedly confirmed,[object Object],Hypothesis- a testable statement about the natural world,[object Object],Belief- a psychological state in which a person holds a premise (or statement) to be true.,[object Object]

Evolution by Natural Selection is a theory,[object Object],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).,[object Object]

Age of the Earth,[object Object],Earth is about 4.5 billion years old,[object Object],Geologists confirmed this approximate date through determining the age of rock formations and the time it would take for them to form,[object Object]

Why does it matter how old the Earth is?,[object Object]

Time is important:,[object Object],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.,[object Object],Other ways we know:,[object Object],Chemical analysis of ice cores,[object Object],radio active fluorine ,[object Object]

Evolution,[object Object],Change in organisms over time,[object Object],These changes are seen in populations not in individuals,[object Object]

Charles Darwin,[object Object],On the Origin of Species in 1859.,[object Object],Darwin supplied evidence that evolution has occurred. He also explained his ideas about how (mechanism) evolution occurs. ,[object Object]

Darwin’s theory was based on artificial selection. In artificial selection, nature provided the variation, and humans selected those variations that they found useful.,[object Object], For example, animal breeders used only the largest hogs, fastest horses, or cows that produced the most milk for breeding.,[object Object]

Artificial Selection,[object Object],Natural Selection,[object Object],Variation in traits exists,[object Object],Breeder selects favorable traits in organism,[object Object],Breeder mates animals with the favorable traits more than other organisms,[object Object],Desired traits become more common in population,[object Object],Variation in traits exists,[object Object],Nature “selects” favorable traits in organism because some of these trait give a reproductive or survival advantage,[object Object],Organisms with favorable traits survive better and have more offspring,[object Object],Traits that give a reproductive/survival advantage become more common in population,[object Object]

Why do both forms of selection require variation?,[object Object]

Sources of variation,[object Object],Genetic Shuffling in Anaphase I of meiosis,[object Object],Mutation to DNA passed down to offspring (very rare!),[object Object]

What is competition?,[object Object]

Competition,[object Object],Competition is a struggle for limited resources in which there can only be one or a few “winners”,[object Object],On Earth we have a finite number of resources; there are many more organisms than resources.,[object Object],A struggle for survival results, the organisms that get the resources will live and pass on their genes to the next generation.,[object Object],Besides limited resources; what are some other challenges organisms must face to survive and reproduce?,[object Object]

Adaptations,[object Object],Traits that provide some type of advantage to organisms in the struggle for survival are called adaptations.,[object Object],There are recognizable patterns to the way organisms adapt,[object Object]

Predict what will happen to a bunny population with a brown fur mutation in an equatorial environment.,[object Object]

Convergence,[object Object],Unrelated species respond to environmental pressures with similar functional adaptations,[object Object]

Divergence,[object Object],Humans DID NOT come from apes, rather both species had a common ancestor long ago,[object Object],IDA,[object Object]

Draw a diagram of how scientist would describe the relationship between Ida, humans and apes.,[object Object]

Adaptive Radiation,[object Object],Adaptive radiation is the pattern of adaptation that isolates a species into two separate lineages,[object Object]

Co-Evolution,[object Object],Co-evolution is when a species directly influences the evolution of another species and both populations evolve in parallel.,[object Object]

Adj natural selection

Adj natural selection

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Adj natural selection