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Questions and Answers
What is synamorphology?
What are synapomorphies?
Often evolutionary innovations
What distinguishes a synapomorphy?
A shared, derived characteristic that is common between an ancestor and its descendants.
How are synapomorphies useful?
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Provide an example of a synapomorphy.
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When defining birds, wings are considered to be:
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What are lobe-fins in tetrapods considered?
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What does the increase in the number of thoracolumbar vertebrae in the Afrotheria clade represent?
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What are feathers classified as?
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What is a plesiomorphy?
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Define taxa.
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The trait of a bird species having a mask is considered to be:
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Why can't a plesiomorphic character reveal information about relationships?
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In a clade including lizards and dinosaur crocodiles, having legs is:
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In respect to grouping the evolution of living things, how are plesiomorphies compared to synapomorphies?
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Why is hair considered a plesiomorphy and a symplesiomorphy in primates?
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What constitutes a monophyletic group?
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What are aves classified as?
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What does the 'scissor test' determine?
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What defines a polyphyletic group?
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What is a paraphyletic group?
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How is the identification of a paraphyletic group shown using the 'scissor test'?
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What does the difference between monophyletic, polyphyletic, and paraphyletic groups pertain to?
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What is convergent evolution?
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Provide an example of convergent evolution.
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What happens to analogous characteristics due to convergent evolution?
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Match the following organisms with their analogous features:
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What is the shared physical structure of bats and birds most likely due to?
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What role does convergent evolution play in producing analogous traits?
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Study Notes
Basic Concepts in Phylogenetics
- Synapomorphology refers to a homologous trait shared by some members of a group but not all.
- Synapomorphies are commonly evolutionary innovations that help identify relationships among species.
- A synapomorphy is a shared, derived trait that distinguishes a clade from other organisms, demonstrating common ancestry.
- Synapomorphies are essential in constructing a phylogenetic tree, which maps evolutionary relationships.
Examples of Synapomorphies
- Transition from five toes to a single hoof is an example of a synapomorphy in horses and donkeys.
- In mammals, features like hair, milk, and a four-chambered heart contrast with reptiles and serve as synapomorphies.
- Wings are considered a synapomorphy when defining birds.
- Lobe-fins in tetrapods are recognized as a synapomorphy.
Features in Clades
- The vertebral column in mammals is often conserved, but an increased number of thoracolumbar vertebrates in the Afrotheria clade (including elephants) represents a derived trait.
- Feathers are identified as a synapomorphy specifically for birds.
Plesiomorphies and Taxa
- A plesiomorphy is an ancestral trait shared by multiple taxa, which does not provide specific information about relationships in phylogenetic trees.
- Taxa refer to groups classified in biological hierarchy based on related organisms.
Functional Trait Examples
- The mask trait in bird species is categorized as a plesiomorphy.
- Plesiomorphies are generally less useful in determining evolutionary relationships compared to synapomorphies.
Clades and Group Definitions
- A monophyletic group includes a common ancestor and all its descendants.
- Aves (birds) form a monophyletic group.
- The "scissor test" is used to assess monophyly; a single cut should suffice.
- A polyphyletic group lacks a direct common ancestor.
- A paraphyletic group consists of a monophyletic section with some descendants excluded.
Testing Group Types
- Identifying a paraphyletic group using the "scissor test" requires trimming part of a derived branch.
- Differences among monophyletic, polyphyletic, and paraphyletic groups revolve around variations in common ancestry.
Evolutionary Processes
- Convergent evolution describes how unrelated species develop similar traits due to analogous lifestyles.
- An illustration of convergent evolution includes the similarities between falcons (birds), bats (mammals), and pterodactyls (reptiles).
- Analogous characteristics, like those found in bats and birds, arise from convergent evolution rather than shared ancestry.
Characteristics of Analogous Structures
- Due to convergent evolution, analogous characteristics appear similar across different species despite dissimilar evolutionary backgrounds.
- Examples of organisms exhibiting analogous structures include bats, butterflies, beetles, and dragonflies.
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Description
This quiz features flashcards designed to help you understand fundamental concepts in phylogenetics, including terms like synapomorphology and synapomorphies. Test your knowledge on how these traits relate to evolutionary relationships among organisms. Perfect for students looking to grasp the basics of evolutionary biology.