The Upright Ape: A New Origin of the Species

by Aaron G. Filler, MD, PhD

Figure 7-3 Hox Gene Losses in the Course of Bilaterian Evolution
Hox Gene Losses

Figure 7-3 - Hox gene losses.

Hox genes that are present in both modern vertebrates and in insects may be missing in some chordates and other deuterostomes. Before this was understood, zoologists believed that complex animals such as the insects and the vertebrates evolved separately from simple ancestors. It now appears that there was a complex common ancestor and that some simple types of animals evolved by loss of genes and progressive simplification.

Figure credit -

Redrawn, modified after: Ikuta, T. and H. Saiga (2005). Organization of Hox genes in ascidians: present, past, and future. Developmental Dynamics233(2): 382-9.

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