Solved Phylogenetic trees worksheet 1. Consider the | Chegg.com - Free Printable

Problem Analysis

The task involves analyzing a phylogenetic tree to answer questions about monophyletic groups, common ancestors, and evolutionary relationships. Let's break down each part of the problem step by step.

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Part (a): Would a group composed only of fungi and Fonticula be monophyletic? Justify your answer.

#### Definition of Monophyletic Group
A monophyletic group (or clade) consists of an ancestor and all of its descendants. In other words, a monophyletic group must include the most recent common ancestor of all its members and no additional taxa outside this lineage.

#### Analysis
1. Identify the position of Fungi and Fonticula in the tree:
- Fungi are located at node 8.
- Fonticula is a subgroup within Fungi, located at node 9.

2. Check if the group "Fungi + Fonticula" is monophyletic:
- Since Fonticula is already a subset of Fungi, including both Fungi and Fonticula together does not add any new taxa outside the Fungi lineage.
- The most recent common ancestor of Fungi (node 8) is also the ancestor of Fonticula (node 9).
- Therefore, the group "Fungi + Fonticula" includes all descendants of node 8 and nothing more.

3. Conclusion:
- The group composed of Fungi and Fonticula is indeed monophyletic because it includes an ancestor (node 8) and all its descendants.

#### Final Answer for Part (a):
$$
\boxed{\text{Yes, the group composed of fungi and Fonticula is monophyletic.}}
$$

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Part (b): Identify a monophyletic group of your choice that includes choanoflagellates. List all of the members of this group and the node of the common ancestor.

#### Analysis
1. Identify the position of Choanoflagellates in the tree:
- Choanoflagellates are located at node 10.

2. Choose a monophyletic group that includes Choanoflagellates:
- A monophyletic group must include the most recent common ancestor of Choanoflagellates and all its descendants.
- One possible choice is the group that includes Choanoflagellates, Sponges, Insects, and Vertebrates. This group shares a common ancestor at node 11.

3. List the members of this group:
- Members: Choanoflagellates, Sponges, Insects, Vertebrates.
- Common ancestor: Node 11.

#### Final Answer for Part (b):
$$
\boxed{\text{Monophyletic group: Choanoflagellates, Sponges, Insects, Vertebrates; Common ancestor: Node 11.}}
$$

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Part (c): Which node represents the most recent common ancestor of land plants and animals?

#### Analysis
1. Identify the positions of Land Plants and Animals in the tree:
- Land Plants are located at node 5.
- Animals are located at node 13.

2. Trace back to the most recent common ancestor:
- Land Plants (node 5) and Animals (node 13) share a common ancestor at node 3. This is the point where their lineages diverge from a common ancestor.
- Node 3 is the most recent common ancestor of both Land Plants and Animals.

#### Final Answer for Part (c):
$$
\boxed{\text{Node 3}}
$$

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Summary of Answers:

1. Part (a): Yes, the group composed of fungi and Fonticula is monophyletic.
2. Part (b): Monophyletic group: Choanoflagellates, Sponges, Insects, Vertebrates; Common ancestor: Node 11.
3. Part (c): Node 3.