How Does a Cladogram Reveal Evolutionary Relationships? - Free Printable
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Step-by-step solution for: How Does a Cladogram Reveal Evolutionary Relationships?
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Show Answer Key & Explanations
Step-by-step solution for: How Does a Cladogram Reveal Evolutionary Relationships?
You’re looking at a cladogram — a diagram that shows evolutionary relationships among organisms based on shared derived characteristics (called *synapomorphies*). The goal is to understand how these organisms are related through common ancestry and to identify which traits evolved when.
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#### 🧬 What is a Cladogram?
A cladogram is a branching diagram that represents the evolutionary relationships among organisms. Each branch point (node) represents a common ancestor, and the branches show lineages that diverged from that ancestor. Organisms that share more recent common ancestors are more closely related.
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The cladogram shows 6 organisms:
1. Worm (A)
2. Spider (B)
3. Scorpion (C)
4. Centipede (D)
5. Dragonfly (E)
6. Butterfly (F)
And 7 traits (labeled 1–7) that evolved along the branches:
1. Segmented body
2. Exoskeleton
3. Jointed appendages
4. Wings
5. Three body parts (head, thorax, abdomen)
6. Metamorphosis
7. Two pairs of wings
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We’ll trace the evolution of traits and see which organisms share which traits — this reveals their evolutionary closeness.
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## 🌱 TRAIT EVOLUTION & ORGANISM RELATIONSHIPS:
Let’s walk up the cladogram from the bottom (most ancestral) to the top (most derived):
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- Found in ALL organisms shown → This is the most ancient trait.
- Worm (A) has it → all others inherited it from a common ancestor with the worm.
→ So, segmented body is the basal trait for this group.
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- Appears after the worm → first seen in spider (B), scorpion (C), centipede (D), dragonfly (E), butterfly (F).
→ So, exoskeleton evolved in the common ancestor of arthropods (excluding worms).
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- Also appears after worm → same group as exoskeleton.
→ All arthropods have jointed legs/appendages.
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- First appears at the branch leading to dragonfly (E) and butterfly (F).
→ So, wings evolved in the common ancestor of insects (like dragonflies and butterflies).
→ Spiders, scorpions, and centipedes do NOT have wings → they branched off before wings evolved.
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- Seen only in dragonfly (E) and butterfly (F).
→ This is a more specific insect trait.
→ Centipedes have many segments; spiders/scorpions have two main body parts (cephalothorax + abdomen).
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- Only in butterfly (F).
→ Butterflies undergo complete metamorphosis (egg → larva → pupa → adult).
→ Dragonflies undergo incomplete metamorphosis (nymph → adult), so they don’t share this trait.
→ So, metamorphosis (complete) is a unique derived trait for butterflies.
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- Only in butterfly (F).
→ Dragonflies also have two pairs of wings, but wait — why is this listed separately?
> ❗️Actually, this may be an error or simplification in the diagram. Both dragonflies and butterflies have two pairs of wings. But since Trait 4 (wings) is already listed, and Trait 7 is placed only at the butterfly branch, it likely refers to specific wing structure or function — perhaps “membranous wings” or “scaled wings” — or it's meant to highlight that butterflies retained both pairs while some insects lost one pair (like flies).
But according to the diagram’s logic:
→ Butterfly has Trait 7 → it’s a derived trait unique to its lineage.
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## 🧬 EVOLUTIONARY RELATIONSHIPS REVEALED:
- Worm (A) is the outgroup — least related to the others.
- Spider (B), Scorpion (C), Centipede (D) are more closely related to each other than to insects — they form a group called chelicerates (spiders/scorpions) and myriapods (centipedes), which diverged before wings evolved.
- Dragonfly (E) and Butterfly (F) are insects — they share wings, three-part body, etc.
- Butterfly (F) is the most derived — it has all the traits including metamorphosis and possibly specialized wings.
---
## 📌 KEY TAKEAWAY:
> A cladogram reveals evolutionary relationships by showing shared derived traits (synapomorphies) that evolved in common ancestors. Organisms that share more recent traits are more closely related.
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## ✔ FINAL ANSWER TO “HOW DOES A CLADOGRAM REVEAL EVOLUTIONARY RELATIONSHIPS?”
> A cladogram reveals evolutionary relationships by mapping the order in which shared derived traits (synapomorphies) evolved. Organisms that share more recent traits are more closely related, having diverged from a more recent common ancestor. The branching pattern reflects the sequence of evolutionary divergence — the closer two organisms are on the tree, the more recently they shared a common ancestor.
In this example:
- Worms are the earliest branch.
- Arthropods (spiders, scorpions, centipedes, insects) share exoskeletons and jointed limbs.
- Insects (dragonflies, butterflies) share wings and three-part bodies.
- Butterflies are the most derived, with unique traits like complete metamorphosis.
---
✔ You’ve now solved the problem!
This cladogram helps us understand not just *who* is related to *whom*, but *when* key traits evolved during their evolutionary history.
Let me know if you want to label the nodes or draw the tree yourself — I can guide you step-by-step!
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🔍 STEP-BY-STEP EXPLANATION:
#### 🧬 What is a Cladogram?
A cladogram is a branching diagram that represents the evolutionary relationships among organisms. Each branch point (node) represents a common ancestor, and the branches show lineages that diverged from that ancestor. Organisms that share more recent common ancestors are more closely related.
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📊 THE CLADOGRAM IN YOUR IMAGE
The cladogram shows 6 organisms:
1. Worm (A)
2. Spider (B)
3. Scorpion (C)
4. Centipede (D)
5. Dragonfly (E)
6. Butterfly (F)
And 7 traits (labeled 1–7) that evolved along the branches:
1. Segmented body
2. Exoskeleton
3. Jointed appendages
4. Wings
5. Three body parts (head, thorax, abdomen)
6. Metamorphosis
7. Two pairs of wings
---
✔ SOLVING THE TASK: “How Does a Cladogram Reveal Evolutionary Relationships?”
We’ll trace the evolution of traits and see which organisms share which traits — this reveals their evolutionary closeness.
---
## 🌱 TRAIT EVOLUTION & ORGANISM RELATIONSHIPS:
Let’s walk up the cladogram from the bottom (most ancestral) to the top (most derived):
---
➤ Trait 1: Segmented Body
- Found in ALL organisms shown → This is the most ancient trait.
- Worm (A) has it → all others inherited it from a common ancestor with the worm.
→ So, segmented body is the basal trait for this group.
---
➤ Trait 2: Exoskeleton
- Appears after the worm → first seen in spider (B), scorpion (C), centipede (D), dragonfly (E), butterfly (F).
→ So, exoskeleton evolved in the common ancestor of arthropods (excluding worms).
---
➤ Trait 3: Jointed Appendages
- Also appears after worm → same group as exoskeleton.
→ All arthropods have jointed legs/appendages.
---
➤ Trait 4: Wings
- First appears at the branch leading to dragonfly (E) and butterfly (F).
→ So, wings evolved in the common ancestor of insects (like dragonflies and butterflies).
→ Spiders, scorpions, and centipedes do NOT have wings → they branched off before wings evolved.
---
➤ Trait 5: Three Body Parts (Head, Thorax, Abdomen)
- Seen only in dragonfly (E) and butterfly (F).
→ This is a more specific insect trait.
→ Centipedes have many segments; spiders/scorpions have two main body parts (cephalothorax + abdomen).
---
➤ Trait 6: Metamorphosis
- Only in butterfly (F).
→ Butterflies undergo complete metamorphosis (egg → larva → pupa → adult).
→ Dragonflies undergo incomplete metamorphosis (nymph → adult), so they don’t share this trait.
→ So, metamorphosis (complete) is a unique derived trait for butterflies.
---
➤ Trait 7: Two Pairs of Wings
- Only in butterfly (F).
→ Dragonflies also have two pairs of wings, but wait — why is this listed separately?
> ❗️Actually, this may be an error or simplification in the diagram. Both dragonflies and butterflies have two pairs of wings. But since Trait 4 (wings) is already listed, and Trait 7 is placed only at the butterfly branch, it likely refers to specific wing structure or function — perhaps “membranous wings” or “scaled wings” — or it's meant to highlight that butterflies retained both pairs while some insects lost one pair (like flies).
But according to the diagram’s logic:
→ Butterfly has Trait 7 → it’s a derived trait unique to its lineage.
---
## 🧬 EVOLUTIONARY RELATIONSHIPS REVEALED:
- Worm (A) is the outgroup — least related to the others.
- Spider (B), Scorpion (C), Centipede (D) are more closely related to each other than to insects — they form a group called chelicerates (spiders/scorpions) and myriapods (centipedes), which diverged before wings evolved.
- Dragonfly (E) and Butterfly (F) are insects — they share wings, three-part body, etc.
- Butterfly (F) is the most derived — it has all the traits including metamorphosis and possibly specialized wings.
---
## 📌 KEY TAKEAWAY:
> A cladogram reveals evolutionary relationships by showing shared derived traits (synapomorphies) that evolved in common ancestors. Organisms that share more recent traits are more closely related.
---
## ✔ FINAL ANSWER TO “HOW DOES A CLADOGRAM REVEAL EVOLUTIONARY RELATIONSHIPS?”
> A cladogram reveals evolutionary relationships by mapping the order in which shared derived traits (synapomorphies) evolved. Organisms that share more recent traits are more closely related, having diverged from a more recent common ancestor. The branching pattern reflects the sequence of evolutionary divergence — the closer two organisms are on the tree, the more recently they shared a common ancestor.
In this example:
- Worms are the earliest branch.
- Arthropods (spiders, scorpions, centipedes, insects) share exoskeletons and jointed limbs.
- Insects (dragonflies, butterflies) share wings and three-part bodies.
- Butterflies are the most derived, with unique traits like complete metamorphosis.
---
✔ You’ve now solved the problem!
This cladogram helps us understand not just *who* is related to *whom*, but *when* key traits evolved during their evolutionary history.
Let me know if you want to label the nodes or draw the tree yourself — I can guide you step-by-step!
Parent Tip: Review the logic above to help your child master the concept of cladogram worksheet answers.
