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Complex Traits

Author(s): Nancy Moreno, PhD.

Diagram Based on Genetic Information

In the diagram above, species A and B are more closely related to each other more than to any other species or cluster of species on the diagram. Similarly, species C and D are more closely related to each other than to a member of any other group. Of the species on the diagram, species E is the least related to any of the other groups. 

This type of diagram, in which groups are defined by shared inherited characteristics, usually is called a phylogeny or phylogenetic tree. The term phylogeny comes from the Greek words, phylon (tribe or clan) and genesis (origin). 

Procedure (cont.)

5. Explain to students that scientists now can use genetic information to estimate the relationships among different groups of species. Species that are more closely related share more genetic information. In the slide, the numbers in red represent similar versions of genes. Ask, Which numbers are shared by all of the groups? [1,2,3]. Which numbers distinguish the branch containing Species A, B, C and D, from the branch with Species E? [4]. How are the branches with Species A and B, and C and D different? 

One also can say that Species A and B share a common ancestor, as do Species C and D. The entire group of Species shares a more distant common ancestor, which was characterized only by genes 1, 2 and 3.

Funded by the following grant(s)

Science Education Partnership Award, NIH

Gene U: Inquiry-based Genomics Learning Experiences for Teachers and Students
Grant Number: 5R25OD011134

Robert Wood Johnson Foundation

Using Learning Technology to Build Human Capital
Grant Number: 57363