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Questions and Answers
Which group is considered a monophyletic group (clade)?
Which group is considered a paraphyletic group?
Which group is considered a polyphyletic group?
What is the main characteristic of a monophyletic group?
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What is the main characteristic of a paraphyletic group?
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What is the main characteristic of a polyphyletic group?
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Which group is not considered a monophyletic group?
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Which group does not include all the descendants of the common ancestor?
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Which group includes species that have different common ancestors?
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Which group consists of an ancestral species and all of its descendants?
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Which of the following statements is true about shared ancestral characters?
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What is the difference between shared ancestral and shared derived characters?
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Which of the following is an example of a shared derived character?
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What is an ingroup?
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What is an outgroup?
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What can the branch lengths in a phylogenetic tree indicate?
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Which group of organisms is polyphyletic?
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What does it mean for a group to be polyphyletic?
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What can help to infer evolutionary relationships?
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Which of the following is an example of a shared ancestral character?
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Study Notes
Phylogenetic Groups
- Monophyletic Group (Clade): Comprises an ancestral species and all its descendants, forming a complete branch on the tree of life.
- Paraphyletic Group: Consists of an ancestral species and some, but not all, of its descendants, leading to an incomplete representation of a lineage.
- Polyphyletic Group: Includes species that do not share a recent common ancestor, grouping together organisms based on similar traits rather than common ancestry.
Characteristics of Groups
- Main Characteristic of Monophyletic Group: Contains all descendants from a common ancestor, illustrating true evolutionary relationships.
- Main Characteristic of Paraphyletic Group: Lacks some descendants of a common ancestor, resulting in a fragmented view of evolution.
- Main Characteristic of Polyphyletic Group: Groups organisms that may share physical traits yet have diverged from different ancestral lines.
Evolutionary Relationships
- Groups Not Considered Monophyletic: Paraphyletic and polyphyletic groups lack the completeness of a true clade.
- Group Lacking All Descendants: Paraphyletic group does not include every descendant of a common ancestor.
- Group with Different Common Ancestors: Polyphyletic group consists of species with varied evolutionary backgrounds.
Shared Characters
- Shared Ancestral Characters: Traits inherited from a distant ancestor, applicable to a broader range of organisms in a lineage.
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Difference Between Shared Ancestral and Derived Characters:
- Shared Ancestral Characters are primitive traits shared by all members of a clade.
- Shared Derived Characters are traits that have evolved more recently and characterize a more specific group.
Additional Terms
- Example of Shared Derived Character: The presence of feathers in birds, distinguishing them from other reptiles.
- Ingroup: The group of organisms being studied, which share certain derived traits.
- Outgroup: A species or group outside of the ingroup, used as a reference point in phylogenetic analysis.
Phylogenetic Trees
- Branch Lengths: Indicate the amount of evolutionary change or time between nodes in a phylogenetic tree.
- Polyphyletic Groups in Organisms: Often occur in classifications such as marine mammals (whales, dolphins) grouped with fish, which do not share a common ancestor.
- Inference of Evolutionary Relationships: Analyzing shared derived characters can help in determining how closely related different organisms are.
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Description
Test your knowledge of cladistics with this quiz! Learn about monophyletic, paraphyletic, and polyphyletic groups and how they are classified in evolutionary biology. Can you identify the correct classification for the given species? Find out now!
