Presentation on theme: "Imagine that you are traveling in Madagascar when you find the plant to the left. You see that the plant has an unusually large spur containing nectar."— Presentation transcript:
Imagine that you are traveling in Madagascar when you find the plant to the left. You see that the plant has an unusually large spur containing nectar in its tip. You remember learning in science class that some moths feed on nectar. Draw a picture of what you think a moth may look like that feeds on this plant. How might natural selection bring about the evolution of this orchid and the moth?
KEY CONCEPT Evolution occurs in patterns.
REMEMBER: Evolution through natural selection is not random. Natural selection can have direction. The effects of natural selection add up over time.
The 3 patterns we’re going to discuss today are: 1.Coevolution 2.Convergent Evolution 3.Divergent Evolution – We’ll also look at how these might be seen in the fossil record
Coevolution can occur with species that help or compete with each other
Mimicry occurs when one organism evolves to look like the other in order to benefit itself. The mimic benefits from the situation while the organism it mimics in unaffected. Example: Example: Orchid flowers that mimic female wasps Mimicry is another example of coevolution
Convergent evolution describes evolution toward similar traits in unrelated species. When two species are similar in a particular characteristic, it’s only convergent evolution if their ancestors were not similar Convergent Evolution
Divergent evolution describes evolution toward different traits in closely related species. Divergent evolution can lead to speciation. kit fox ancestor red fox
Changes in the frequency of a gene in the gene pool initially leads to microevolution. Microevolution refers to a small change in a population over a short amount of time. Many small changes eventually lead to macroevolution. Macroevolution refers to the sum total of many changes that transform organisms over a long period of time. Macroevolution leads to speciation or the creation of a new species. When an evolving population can no longer interbreed with the original population, a new species is formed.
Things to Consider: Stasis - The organisms in the fossil record looks the same from when they appear to when they disappear; Sudden appearance - When a species does not arise by gradually changing steadily from its ancestors; it appears all at once and fully formed. Sequential nature – Based on the layers of rock, we sequence organisms in the fossil record. What might cause stasis or sudden appearance? So what about the fossil record…
WHICH PATTERN IS IT? coevolution convergent evolution divergent evolution divergent evolution The Galápagos finches evolved through natural selection from a common ancestor into a wide variety of different looking species with different kinds of beaks
WHICH PATTERN IS IT? coevolution convergent evolution divergent evolution coevolution Hummingbirds have a beak just the right length to reach the nectar in a cardinal flower and as they feed their foreheads bump into the pollen structure. Cardinal flowers are red which hummingbirds can see, but bees can’t, and their pollen structure is at just the right height for the hummingbird to pick up pollen as it feeds.
WHICH PATTERN IS IT? coevolution convergent evolution divergent evolution Convergent evolution Whales, sharks, and penguins all have streamlined bodies and fins/flipper for moving in water even though they belong in different animal groups (mammals, fish, and birds)
WHICH PATTERN IS IT? coevolution convergent evolution divergent evolution Adaptive radiation OR divergent evolution Beaver in North America and capybara in South America are closely related species living in very different environments that have evolved to look different over time. Beaver NORTH AMERICA Muskrat Capybara SOUTH AMERICA Coypu Beaver Muskrat Beaver and Muskrat Coypu BIOLOGY by Miller and Levine Pearson Publishing
WHICH PATTERN IS IT? coevolution convergent evolution divergent evolution divergent evolution The tortoises on the Galapagos islands share a common ancestor, but over time they have become adapted for obtaining food in different habitats on different islands by having different neck lengths