Hox gene evolution: multiple mechanisms contributing to evolutionary novelties.
Hox genes, which are important for determining regional identity in organisms as diverse as flies and humans, are typically considered to be under strong evolutionary constraints because large changes in body plan are usually detrimental to survival. Despite this, there is great body plan diversity in nature, and many of the mechanisms underlying this diversity have been attributed to changes in Hox genes. Over the past year, several studies have examined how Hox genes play a role in evolution of body plans and novelties. Here, we examine four distinct evolutionary mechanisms implicated in Hox gene evolution, which include changes in (1) Hox gene expression, (2) downstream Hox target gene regulation without change in Hox expression, (3) protein-coding sequence, and (4) posttranscriptional regulation of Hox gene function. We discuss how these types of changes in Hox genes--once thought to be evolutionarily static--underlie morphological diversification. We review recent studies that highlight each of these mechanisms and discuss their roles in the evolution of morphology and novelties.
Department of Entomology and Program in Molecular & Cell Biology, University of Maryland, College Park, Maryland 20742, USA. lpick@umd.edu
Leslie
L
Pick
Alison
A
Heffer
D000818:Animals; D051943:Antennapedia Homeodomain Protein / Q000235:genetics; D019521:Body Patterning / Q000235:genetics; D029721:Drosophila Proteins / Q000235:genetics; D019143:Evolution, Molecular; D051717:Fushi Tarazu Transcription Factors / Q000235:genetics; D015870:Gene Expression; D005801:Genes, Homeobox; D006801:Humans; D007313:Insecta / Q000235:genetics / Q000254:growth & development; D008322:Mammals / Q000235:genetics / Q000254:growth & development; D008957:Models, Genetic; D005810:Multigene Family; D012104:Reptiles / Q000235:genetics / Q000254:growth & development; D014157:Transcription Factors / Q000235:genetics; D014714:Vertebrates / Q000235:genetics / Q000254:growth & development
D051943:Antennapedia Homeodomain Protein; C497974:Antp protein, Drosophila; D029721:Drosophila Proteins; D051717:Fushi Tarazu Transcription Factors; C059627:Scr protein, Drosophila; D014157:Transcription Factors