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Evolution and Natural Selection 2009 On the left page Where is the animal found? What does the animal look like? What does the animal eat? Connection between adaptations & habitat. What causes populations to change over time? On the left page think of 3 possible answers to this question. 1. 2. 3. Evolution… Charles Darwin Alfred R. Wallace Darwin’s 5 year Voyage On the left page: Why do you think that Darwin Finches have different beaks? Darwin’s Theory of Natural Selection: There is potential for rapid reproduction. Resources are limited and population size is constant. Organisms must compete for survival and reproduction. This is Natural Selection This is Evolution There is variety in body structures and behaviors. Usually, the best adapted organisms survive and leave the most offspring. The genetic makeup of the population changes over time, due to natural selection. Some variability can be passed to the offspring. Evolution Needs: Time: – Takes a long time for organisms to evolve. Variation: – Need different looking and acting organisms in a population- based on genes. Competition: – Organisms must compete with one another– there cannot be enough space, food, mates, for everyone! Different Success Rates: – Different individuals must be more or less successful than one another in passing on their genes (in offspring). Stabilizing Selection Center are the only ones to reproduce Individuals look more similar over time Less variation in new population. Directional Selection Just one side reproduces Population looks different over time Same amount of variation in new population. Peppered moth lab Peppered Moth Lab Disruptive Selection Ends are the only ones to reproduce Produces 2 separate phenotypes over time More variation in new population. What environmental conditions could cause populations to change? Describe the change that had to happen to create the two mice species shown in the bottom picture. Geographic Isolation Geographic Isolation CAUSES Allopatric Speciation. This is when species evolve as a result of being separated from each other. Being in two different environments causes the species to adapt in different ways. How are New Species Maintained? Quick write: Think of as many reasons why tigers and lions don’t make ligers in nature – without human interference Reproductive Isolation Temporal- Breed in different seasons, time of day Behavioral- Courtship differs: not attractive Anatomical (Reproductive) Parts don’t match any more Gametic (Reproductive) Zygotes die or infertile offspring On the left- give an example of one How do we study evolution? On the left side of your notebook, list 3 pieces of EVIDENCE that we can LOOK at to see that evolution occurs. 1. 2. 3. Similar Development ? ? ? ? Homologous Structures: structures that look the same due to… Divergent Evolution: from a common ancestor Analogous Structures: structures that look the same due to… Convergent Evolution due to the need to adapt to similar environments On left side: Double bubble of analogous and homologous structures Similar fossils were found in geographically isolated locations On the left, where do you think we have found similar fossils that demonstrate not only that all the continents were stuck together in the past but also that we have evolved over time? Fossil Evidence Fossil Record- The chronicle (record) of evolution over millions of years of geological time that is demonstrated by the order in which the fossils appear in rock stratus. Microevolution • Small genetic changes in a population • Change in frequency of a single allele due to selection Macroevolution • Large-scale changes in organisms On the left side: create a Venn diagram that compares microevolution to macroevolution