Practice worksheet on evolutionary relationships using cladograms to analyze shared characteristics and genetic similarities among species.

Problem Analysis:

The task involves analyzing a cladogram (a branching diagram that represents evolutionary relationships among species) to answer questions about the evolutionary traits and relationships of different organisms. The cladogram provided in the image shows the evolutionary relationships between various animals, including lampreys, tuna, salamanders, turtles, leopards, sharks, amphibians, reptiles, birds, and mammals.

Cladogram Breakdown:

1. Lampreys are at the base of the tree, indicating they are the most distantly related to the other groups.
2. Tuna is grouped with lampreys but separated by a trait: "Fins evolved from limbs."
3. Salamanders are separated from tuna by another trait: "Four legs."
4. Turtles share a common ancestor with salamanders and leopards, as indicated by the branch leading to them.
5. Leopards are more closely related to turtles than to tuna or lampreys.
6. The cladogram also includes additional traits such as "Egg-laying," "Amniotic egg," "Warm-blooded," and "Fur."

Practice Problems Solution:

#### 1. What trait separates Lampreys from tuna on this cladogram?
- Answer: Fins evolved from limbs.
- Explanation: The cladogram shows that the branch separating lampreys from tuna is labeled "Fins evolved from limbs." This indicates that tuna have fins that evolved from limbs, which is a trait not present in lampreys.

#### 2. What separates a salamander from a turtle?
- Answer: Four legs.
- Explanation: The branch separating salamanders from turtles is labeled "Four legs." This indicates that salamanders and turtles both have four legs, but this trait is used to distinguish them from other groups like tuna and lampreys.

#### 3. Which organisms are most related to the leopard?
- Answer: Turtles.
- Explanation: The cladogram shows that leopards and turtles share a common ancestor, as they are grouped together on the same branch. This indicates that they are more closely related to each other than to other groups like salamanders or tuna.

#### 4. What traits do these two organisms share?
- Answer: Four legs, amniotic egg, warm-blooded.
- Explanation: Leopards and turtles share several traits, including "Four legs," "Amniotic egg," and "Warm-blooded." These traits are indicated by the branches leading to their common ancestor.

#### 5. Which organism will have DNA most similar to the tuna?
- Answer: Lampreys.
- Explanation: Lampreys are the closest relatives to tuna on the cladogram. Since they share a more recent common ancestor compared to other groups, their DNA will be more similar to tuna's DNA.

#### 6. Which organism’s DNA will differ the most from the leopard?
- Answer: Lampreys.
- Explanation: Lampreys are at the base of the cladogram and are the most distantly related to leopards. Therefore, their DNA will differ the most from the leopard's DNA.

Your Turn Solution:

#### Directions:
Use the cladogram below to answer the questions on the backside of this worksheet.

#### Cladogram Details:
- Sharks are at the base of the tree.
- Amphibians are separated from sharks by the trait "Four legs."
- Reptiles are separated from amphibians by the trait "Amniotic egg."
- Birds and Mammals share a common ancestor, as indicated by the branch leading to them.
- Additional traits include "Eggs with shells" and "Fur."

#### Questions (Assuming Similar Format to Practice Problems):

1. What trait separates sharks from amphibians?
- Answer: Four legs.
- Explanation: The branch separating sharks from amphibians is labeled "Four legs."

2. What separates amphibians from reptiles?
- Answer: Amniotic egg.
- Explanation: The branch separating amphibians from reptiles is labeled "Amniotic egg."

3. Which organisms are most related to mammals?
- Answer: Birds.
- Explanation: Birds and mammals share a common ancestor, as indicated by the branch leading to them.

4. What traits do these two organisms share?
- Answer: Amniotic egg, warm-blooded, fur.
- Explanation: Birds and mammals share several traits, including "Amniotic egg," "Warm-blooded," and "Fur."

5. Which organism will have DNA most similar to reptiles?
- Answer: Amphibians.
- Explanation: Amphibians are the closest relatives to reptiles on the cladogram. Their DNA will be more similar to reptiles' DNA compared to other groups.

6. Which organism’s DNA will differ the most from mammals?
- Answer: Sharks.
- Explanation: Sharks are at the base of the cladogram and are the most distantly related to mammals. Therefore, their DNA will differ the most from mammals' DNA.

Final Answer:

\boxed{
\begin{aligned}
1. & \text{ Fins evolved from limbs.} \\
2. & \text{ Four legs.} \\
3. & \text{ Turtles.} \\
4. & \text{ Four legs, amniotic egg, warm-blooded.} \\
5. & \text{ Lampreys.} \\
6. & \text{ Lampreys.} \\
\end{aligned}
}