Help your students understand how molecular evidence is used to investigate evolutionary relationships with this engaging online cladogram-building activity.

This resource guides students through the process of using real genetic sequence data to compare species, identify evolutionary relationships, and interpret cladograms and phylogenetic trees.

Students use an online Cladogram Builder simulation to work through the same core workflow used by researchers: selecting species, retrieving DNA sequence data, aligning sequences, comparing genetic differences, and generating evolutionary trees.

The activity introduces students to key bioinformatics concepts including NCBI GenBank, Clustal Omega, DNA sequence alignment, pairwise genetic differences, molecular clocks, cladograms, and phylogenetic trees.
Students are supported with clear instructions, screenshots, guiding questions, and structured comparison tasks.

The opening section explains how sequence differences can be used as evidence for common ancestry and how fewer differences usually indicate a closer evolutionary relationship.

Students complete four themed investigations:

Activity 1: Eucalyptus Ancestry
Students compare five closely related Eucalyptus taxa using the ITS region, a fast-evolving non-coding DNA region useful for distinguishing closely related plant species.

Activity 2: Mammals, Birds, and Sharks
Students use the COI gene to compare humans, chimpanzees, dolphins, hippopotamuses, great white sharks, and pigeons.

Activity 3: Placental Mammals and Marsupials
Students compare giant pandas, polar bears, domestic dogs, African elephants, and koalas to explore relationships between placental mammals and marsupials.

Activity 4: Flowering Plants and Gymnosperms
Students use the rbcL gene to compare plant species including saguaro cactus, euphorbia, carnation, poinsettia, and Scots pine.

This resource encourages students to make predictions based on appearance and geographical distribution before testing those predictions using molecular data. They then interpret genetic difference matrices and compare their predictions with the cladograms and phylogenetic trees produced by the simulation.

What is included?
Student worksheet/activity guide
Clear step-by-step instructions for using the online simulation
Screenshots of the Cladogram Builder workflow
Four comparative species investigations
Prediction questions based on appearance and distribution
Interpretation tasks using genetic difference data

This is an ideal activity for helping students move beyond simply reading cladograms and into understanding how cladograms can be constructed from molecular evidence. It provides a realistic, accessible introduction to bioinformatics while keeping the workflow manageable for classroom use (no downloads required).