Evidence for Common Ancestry Assignment
In this assignment, you will use your knowledge of comparative anatomy, embryological development, biomolecules (DNA & proteins), and biogeography with fossils to explain how these lines of evidence support the idea of common ancestry among living organisms. You will also address common myths and misconceptions about evolution. This assignment is worth 17 points total. You need a minimum score of 11 points to qualify for the quiz later this week and the test at the end of the unit. Answer each question thoughtfully and in complete sentences where appropriate.
Group 1
Study the image of Darwin's finches above. These birds are an example of how comparative anatomy can provide evidence for common ancestry.
Different beak shapes of finches observed by Darwin in the Galápagos Islands.
Question 1a
Explain how the different beak shapes of Darwin's finches provide evidence for common ancestry and natural selection.
Group 2
Comparative anatomy looks at similarities and differences in the structures of living things. Homologous structures are body parts that are similar in structure but may have different functions, while vestigial structures are body parts that have lost their original function.
Question 2a
Describe the difference between homologous and vestigial structures. Give one example of each and explain how they support the idea of common ancestry.
Group 3
Embryological development is another line of evidence for common ancestry. Many animals show similar patterns of development as embryos.
Question 3a
How does comparing embryos of different species provide evidence for common ancestry? Give an example to support your answer.
Group 4
Biomolecules such as DNA and proteins can be compared between species to determine how closely related they are.
Question 4a
Explain how similarities in DNA sequences between different species can be used as evidence for common ancestry.
Group 5
Fossils and biogeography provide important clues about how species have changed over time and where they lived.
Question 5a
Describe how fossils and the geographic distribution of species (biogeography) support the theory of common ancestry.
Group 6
Read the following statements about evolution. For each one, decide if it is a myth or a fact, and briefly explain your reasoning.
Question 6a
People evolved from monkeys.
Myth. Humans and monkeys share a common ancestor, but humans did not evolve directly from monkeys.
Fact. Humans evolved directly from monkeys.
Question 6b
Organisms adapt to their environment because they want or need to.
Myth. Adaptations occur due to genetic variation and natural selection, not because organisms want or need to change.
Fact. Organisms can adapt because they want to survive.
Question 6c
Evolution requires that only the strongest, smartest, and fastest organisms survive and pass along their genes.
Myth. Evolution favors traits that increase survival and reproduction, not just strength or intelligence.
Fact. Only the strongest survive in evolution.
Question 6d
An organism doesn’t have to reproduce to help pass along their genes.
Myth. Reproduction is not the only way for an organism to help pass its genes to the next generation.
Fact. Traits can be passed without reproduction. For example, wolves don't all reproduce. However, they do help raise the young in their pack which insures some of the shared genes of the pack are passed along.
Question 6e
Evolution moves toward a 'perfect' organism.
Myth. Evolution does not have a goal or direction; it is driven by changes in the environment and genetic variation.
Fact. Evolution is always improving organisms.
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