Evolution of chordate hox gene clusters.
In this article, we consider the role of the Hox genes in chordate and vertebrate evolution from the viewpoints of molecular and developmental evolution. Models of Hox cluster duplication are considered with emphasis on a threefold duplication model. We also show that cluster duplication is consistent with a semiconservative model of duplication, where following duplication, one daughter cluster remains unmodified, while the other diverges and assumes a new architecture and presumably new functions. Evidence is reviewed, suggesting that Hox gene enhancers have played an important role in body plan evolution. Finally, we contrast the invertebrates and vertebrates in terms of genome and Hox cluster duplication which are present in the latter, but not the former. We question whether gene duplication has been important in vertebrates for the introduction of novel features such as limbs, a urogenital system, and specialized neuromuscular interactions.
Department of Molecular, Cellular, and Developmental Biology, Yale University, New Haven, Connecticut 06520, USA.
F H
FH
Ruddle
C T
CT
Amemiya
J L
JL
Carr
C B
CB
Kim
C
C
Ledje
C S
CS
Shashikant
G P
GP
Wagner
D000818:Animals; D001483:Base Sequence; D002645:Chickens; D018076:DNA, Complementary; D019143:Evolution, Molecular; D005399:Fishes; D018398:Homeodomain Proteins / Q000235:genetics*; D006801:Humans; D051379:Mice; D008969:Molecular Sequence Data; D005810:Multigene Family; D014907:Whales; D015027:Zebrafish
D018076:DNA, Complementary; D018398:Homeodomain Proteins; C105702:SpHox8 protein, Strongylocentrotus purpuratus