Podcast
Questions and Answers
What is the term for the parts of a phylogenetic tree that represent the species or groups being studied?
What is the term for the parts of a phylogenetic tree that represent the species or groups being studied?
- Root
- Tips (correct)
- Nodes
- Branches
Which of the following describes a node in a phylogenetic tree?
Which of the following describes a node in a phylogenetic tree?
- A point representing the most recent common ancestor (correct)
- The outgroup
- The most recent species in the phylogeny
- A series of related taxa
What does the 'root' of a phylogenetic tree represent?
What does the 'root' of a phylogenetic tree represent?
- The oldest point in the tree
- The extant species included in the tree
- The most recent common ancestor of all taxa in the tree (correct)
- The most recent species in a lineage
What is the purpose of using an outgroup when constructing a phylogenetic tree?
What is the purpose of using an outgroup when constructing a phylogenetic tree?
Which of the following best describes a 'taxon' in the context of phylogenetics?
Which of the following best describes a 'taxon' in the context of phylogenetics?
In phylogenetic terms, what are 'sister taxa'?
In phylogenetic terms, what are 'sister taxa'?
How does rotating a node on a phylogenetic tree affect the inferred evolutionary relationships?
How does rotating a node on a phylogenetic tree affect the inferred evolutionary relationships?
Which statement aligns best with the concept of a monophyletic group?
Which statement aligns best with the concept of a monophyletic group?
A group containing a common ancestor and some, but not all, of its descendants is called:
A group containing a common ancestor and some, but not all, of its descendants is called:
What defines a polyphyletic group?
What defines a polyphyletic group?
If a phylogeny shows that crocodiles/alligators are most closely related to birds, and turtles are equally related to birds and crocodiles/alligators, what can be inferred?
If a phylogeny shows that crocodiles/alligators are most closely related to birds, and turtles are equally related to birds and crocodiles/alligators, what can be inferred?
In a phylogenetic tree, what does the length of a branch typically represent?
In a phylogenetic tree, what does the length of a branch typically represent?
When analyzing a phylogenetic tree, what does a shared branch point (node) between two taxa indicate?
When analyzing a phylogenetic tree, what does a shared branch point (node) between two taxa indicate?
Which of the following is a valid interpretation of a phylogenetic tree?
Which of the following is a valid interpretation of a phylogenetic tree?
You are constructing a phylogeny for a group of insects. You include an outgroup that is a closely related species of crustaceans. What is the benefit of including this outgroup?
You are constructing a phylogeny for a group of insects. You include an outgroup that is a closely related species of crustaceans. What is the benefit of including this outgroup?
A researcher discovers a new species. To determine its evolutionary relationships, they construct a phylogenetic tree. Which data is most helpful for this purpose?
A researcher discovers a new species. To determine its evolutionary relationships, they construct a phylogenetic tree. Which data is most helpful for this purpose?
What is the purpose of 'pruning' a phylogenetic tree?
What is the purpose of 'pruning' a phylogenetic tree?
Why it is incorrect to assume that humans evolved from chimpanzees, based on a phylogenetic tree?
Why it is incorrect to assume that humans evolved from chimpanzees, based on a phylogenetic tree?
You are comparing two phylogenetic trees for the same group of organisms. The branching order is slightly different in the two trees. What could explain this difference?
You are comparing two phylogenetic trees for the same group of organisms. The branching order is slightly different in the two trees. What could explain this difference?
Which of the following is the MOST accurate statement about phylogenetic trees?
Which of the following is the MOST accurate statement about phylogenetic trees?
Which of the following is the MOST accurate statement about a synapomorphy?
Which of the following is the MOST accurate statement about a synapomorphy?
Why is it important to state at least two nested monophyletic groups?
Why is it important to state at least two nested monophyletic groups?
When provided with a phylogeny and information about a trait, what does marking the tree indicate?
When provided with a phylogeny and information about a trait, what does marking the tree indicate?
From the sister taxa, how can you determine the most recent common ancestor?
From the sister taxa, how can you determine the most recent common ancestor?
Why are stems on phylogenetic trees useful?
Why are stems on phylogenetic trees useful?
Flashcards
Phylogenetic Tree
Phylogenetic Tree
A diagram that depicts the lines of evolutionary descent of different species, organisms, or genes from a common ancestor.
Root (of a phylogenetic tree)
Root (of a phylogenetic tree)
The most basal node of a phylogenetic tree, representing the common ancestor from which all taxa on the tree are derived.
Nodes (phylogenetic tree)
Nodes (phylogenetic tree)
Points on a phylogenetic tree where a lineage splits, representing a speciation event or the divergence of taxa.
Branches (phylogenetic tree)
Branches (phylogenetic tree)
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Tips (phylogenetic tree)
Tips (phylogenetic tree)
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Taxon
Taxon
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Monophyletic Group
Monophyletic Group
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Paraphyletic Group
Paraphyletic Group
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Polyphyletic group
Polyphyletic group
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Pruning a phylogenetic tree
Pruning a phylogenetic tree
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Sister taxon
Sister taxon
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Outgroup
Outgroup
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Synapomorphy
Synapomorphy
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Most Recent Common Ancestor
Most Recent Common Ancestor
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Study Notes
Interpreting Phylogenies
Learning Objectives
- Label the root, nodes, branches, and tips of a phylogenetic tree.
- Identify the type of taxon at the tips, whether it's species or a larger group.
- Circle and label several monophyletic groups, with at least two being nested.
- State at least one synapomorphy that identifies each circled monophyletic group.
- Find the most recent common ancestor of any two given taxa.
- Given a phylogeny and trait information, mark where trait changes occurred on the tree.
Parts of a Phylogeny
- Tips represent the end of the branches and indicate the taxa.
- Branches connect the tips to the root or nodes.
- Root represents the base or origin of the tree.
- Nodes are the points where branches connect together
Key Concepts Illustrated by a Phylogenetic Tree
- Outgroup: It helps determine the direction of evolution on the tree.
- Nodes: These are parts of the tree that connect branches
- Taxon (pl. taxa): Is a group of one or more populations of an organism or organisms seen to form a unit.
- Ancestor: This is where a species believed to be related originated
- Descendent: This illustrates the evolution from one species to other existing species
- Sister Taxa: These are taxa that are each other closest relatives
- Time: The tree can be used to track evolutionary change over time
Types of Groups
- Monophyletic group: Includes ALL descendants of a node.
- Paraphyletic group: Contains some, but not all, descendants of the ancestral node.
- Polyphyletic group: Includes taxa that evolved in very different lineages.
Node Rotation
- Nodes can be rotated without changing evolutionary relationships.
For Next Class
- Watch the video on Great Tree of Life
- Prune a tree to include sharks and rays, lungfish, frogs, caecilians, and birds and bring to class on Wednesday.
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