Hox Genes and Body Plan: Evolution

Abstract

The development of diverse structures on the anterior–posterior axis of animal embryos is dependent on homeotic or Hox genes. The expression and function of the Hox genes varies during evolution and underlies some of the morphological differences in different animal taxa.

Keywords: Homeotic; Hox; transcription; evolution; morphology

Figure 1.

The middle animal on the left is a depiction of the presumed bilateral, worm‐like animal that gave rise to insects such as the Drosophila fruit fly (top left) and the mammal (bottom left). To the right of the fruit fly is a schematic of its Hox gene cluster. The arrows denote the presumed derivation of these genes from the Hox cluster of the bilateral worm‐like ancestor. At bottom right is a schematic of the four Hox gene clusters of a vertebrate, with the arrows denoting homologous relationships between the ancestral Hox genes and the Hox genes in the current Drosophila genome. Different tints used denote which genes are expressed in which anterior–posterior regions of the fruit fly, bilaterian, or mammal body plans.

Figure 2.

The phylogenetic tree shows a conventional branching order of animal groups during evolution. The number of Hox genes in the genomes of present‐dxay animals of these different groups is listed on the right side, adjacent to the branch tips.

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References

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Further Reading

Akam M (1998) Hox genes, homeosis and the evolution of segment identity: no need for hopeless monsters. International Journal of Developmental Biology 42: 445–451.

Carroll SB, Grenier JK and Weatherbee SD (2001) From DNA to Diversity. London, UK: Blackwell Science Limited.

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Holland PW, Booth HA and Bruford EA (2007) Classification and nomenclature of all human homeobox genes. BMC Biology 5: 47.

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Lynch VJ, Roth JJ and Wagner GP (2006) Adaptive evolution of Hox‐gene homeodomains after cluster duplications. BMC Evolutionary Biology 6: 86.

Nam J and Nei M (2005) Evolutionary change of the numbers of homeobox genes in bilateral animals. Molecular Biology and Evolution 22: 2386–2394.

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How to Cite close
Tour, Ella, and McGinnis, William(Apr 2008) Hox Genes and Body Plan: Evolution. In: eLS. John Wiley & Sons Ltd, Chichester. http://www.els.net [doi: 10.1002/9780470015902.a0005113.pub2]