Warm-Up: 5 minutes ON A CLEAN SHEET OF PAPER, summarize how Darwin’s finches are an example of speciation. Use specific information from the diagram above. Include the following terms: Species, geographic isolation, adapt, fit, natural selection, reproductive isolation You’ll be turning this in. Make sure to underline the words as you use them.

Patterns of Evolution Make a T chart on your paper Do not label the columns, yet Make observations and brainstorm thoughts for each column, based on the pictures.

shark Fish Ancestor dolphin Mammal Ancestor Icthysaur (extinct) Reptile Ancestor Side A Side B Marsupials all have a pouch where the young finish their development Marsupial mouse Spotted cuscus Flying phalanger Tasmanian native cat Tasmanian wolf Ancestor Marsupial

Review Placentals Marsupials Mammals mouse Marsupial mouse lemur Spotted cuscus Flying squirrel Flying phalanger bobcat Tasmanian native cat wolf Tasmanian wolf Compare variation in the column of marsupials. What type of evolutionary pattern is this? Why? Compare variation between each placental and its similar-looking marsupial counterpart. What type of evolutionary pattern is this? Why? How would you explain this picture to a friend?

Divergent Evolution When species evolve from other species Results in one species becoming less like the original one over time Live in different ways than the common ancestor Caused by migration or nearby extinction of a nearby environment Ex. Darwin’s finches, Marsupials in Australia, Hamlet coral reef fishes

Convergent Evolution When unrelated organisms evolve similarities when adapting to similar environments Live in relatively the same way as each other Related to different ancestors from each other Although these organisms live in different places of the world, they look similar because they adapted to similar environments.

Using Evidence - Biogeography Elephants – found in Africa and India, and not in places with identical climate in Brazil Proboscidean fossils have been found in Africa, Asia, Europe and North and South America. They show that the ancestors of modern elephants moved around the globe.

Homologous structures can be used as evidence for which pattern of evolution?

Analogous structures could be used as evidence for which pattern?

What type am I?

Looking at Variation

Let’s Review Darwin’s conclusions… 1. There is a constant struggle for existence 2. Everything that is born will not survive and reproduce 3. There is variation in nature 4. Natural selection (organisms more fit for their environment will have a better chance of surviving and reproducing) 5. Vast amounts of time have been available for change

Let’s Look at Variation Activity

Types of Natural Selection Activity Get with your partner. 1. Read Scenario #1 and follow the directions. 2. On the back of your graph, summarize what it means. 3. Repeat steps 1 and 2 above.

Stabilizing Selection This type of natural selection favors average individuals. In this way, variation in a population is reduced. Evolution does not occur. Selection against both extremes keep curve narrow and in same place. Stabilizing Selection High mortality, low fitness Low mortality, high fitness

Directional Selection The woodpeckers with the longer beaks are more fit for this environment, so there are more of them then ones with shorter beaks. Selection for longer beaks

Directional Selection By favoring either of the extreme forms of a trait, directional selection can lead the one population to evolve into a new species.

Disruptive Selection In this type, both extreme forms of a trait are favored. In some cases, there may be no intermediate forms, which can lead to the evolution of two new species. (Speciation occurs)

Closure: Sketch a graph that would show the variation of colors from light to dark in these shells. Sketch a graph that would show the changes that would occur if the light colored sand were replaced by darker sand. Sketch a graph that would show the changes that would occur if there were patches of light and dark colored sand. Which scenario would provide the best chance for speciation to occur and why? Explain how disruptive selection is related to speciation…how would you explain it to another person?