Chapter 19.2, Problem 1BC

Development in Animals I: Pattern Formation

Core Skill: Connections Look ahead to Figure 24.15. How is the number of Hox genes related to the complexity of animal bodies?

Figure 24.15 Hox gene number and body complexity in different types of animals. Researchers speculate that the duplication of Hox genes and Hox gene clusters played a key role in the evolution of more complex body patterns in animals. A correlation is observed between increasing numbers of Hox genes and increasing complexity of body patterns. The Hox genes are divided into four groups, called anterior, group 3, central, and posterior, based on their relative similarities. Each group is represented with a different color in this figure.