Phylogeny Review Worksheet 2017 | PDF | Phylogenetic Tree ... - Free Printable

Problem Analysis:

The worksheet provided is about phylogenetic trees and cladograms, which are used to represent evolutionary relationships among species. The task involves analyzing the given cladogram (Tree 1) and answering questions related to character evolution, clades, and common ancestors.

---

Solution:

#### Tree 1:

1. Identify at least five characters possessed by birds:
- From the cladogram, the characters possessed by birds are:
1. Feathers: Birds are characterized by having feathers.
2. Avian endothermy: Birds exhibit avian endothermy, which is a specialized form of warm-bloodedness.
3. Bipedalism: Birds are bipedal, meaning they walk on two legs.
4. Lipovitellin: This is a yolk protein found in bird eggs.
5. Amniotic egg: Birds lay amniotic eggs, which have a protective shell and membranes.

2. Identify two characters possessed by reptiles/birds (the group comprised of turtles, lizards, snakes, crocodiles + dinosaurs + birds; including their common ancestors):
- The shared characters for this group are:
1. Amniotic egg: All these animals lay amniotic eggs.
2. Keratinized skin: They possess keratinized skin, which helps in water retention and protection.

3. Identify four characters possessed by mammals:
- From the cladogram, the characters possessed by mammals are:
1. Hair: Mammals have hair or fur.
2. Endothermy: Mammals are endothermic (warm-blooded).
3. Mammary glands: Mammals have mammary glands for producing milk.
4. Placenta: Mammals have a placenta for nourishing developing embryos.

4. A clade is a group of species each of which includes an ancestral species and all of its descendants. This is also known as a monophyletic group.
- True or False: On their own, turtles, lizards, snakes, crocodiles, and dinosaurs form a clade.
- False: Turtles, lizards, snakes, crocodiles, and dinosaurs do not form a clade because they do not include all descendants of their common ancestor. For example, birds are descendants of dinosaurs but are not included in this group.
- True or False: On their own, crocodiles, dinosaurs, and birds form a clade.
- True: Crocodiles, dinosaurs, and birds share a common ancestor and include all descendants of that ancestor, forming a clade.

5. According to the cladogram, which character evolved first: the amniotic egg or hair?
- The amniotic egg evolved first. It is shown at the base of the tree, indicating it is a more ancient trait compared to hair, which is specific to mammals.

6. According to the cladogram, which character evolved first: keratinized skin or bipedalism?
- Keratinized skin evolved first. It is shown lower in the tree compared to bipedalism, which is specific to birds.

7. On the cladogram, circle the node that represents the most recent common ancestor of crocodiles, dinosaurs, and birds.
- The most recent common ancestor of crocodiles, dinosaurs, and birds is the node where the branches for these groups diverge. This node is located above the "keratinized skin" character and below the "amniotic egg" character.

---

#### Tree 2:

This tree is not fully analyzed in the question, so I will summarize the key features:
- The cladogram shows the evolutionary relationships between fish, amphibians, reptiles, birds, and mammals.
- Characters such as "jaw," "claws or nails," "feathers," "fur," and "lungs" are indicated along the branches.

If there are specific questions related to Tree 2, please provide them, and I can address them accordingly.

---

Final Answers:

1. Characters possessed by birds: Feathers, avian endothermy, bipedalism, lipovitellin, amniotic egg.
2. Characters possessed by reptiles/birds: Amniotic egg, keratinized skin.
3. Characters possessed by mammals: Hair, endothermy, mammary glands, placenta.
4.
- Turtles, lizards, snakes, crocodiles, and dinosaurs form a clade: False.
- Crocodiles, dinosaurs, and birds form a clade: True.
5. Character that evolved first: Amniotic egg.
6. Character that evolved first: Keratinized skin.
7. Node representing the most recent common ancestor of crocodiles, dinosaurs, and birds: Circle the node above "keratinized skin" and below "amniotic egg."

Final Answer:
\boxed{
\text{1. Feathers, avian endothermy, bipedalism, lipovitellin, amniotic egg.}
\text{2. Amniotic egg, keratinized skin.}
\text{3. Hair, endothermy, mammary glands, placenta.}
\text{4. False, True.}
\text{5. Amniotic egg.}
\text{6. Keratinized skin.}
\text{7. Circle the node above "keratinized skin" and below "amniotic egg."}
}