Hoxgene evolution: multiple mechanisms contributing to evolutionary novelties

Abstract

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.

The regulation of Hox gene expression during animal development

“…We consider that this is important given that models of how genes are molecularly regulated constrain our understanding of how they might exert their control over development in health and disease. For the developmental and evolutionary functions of Hox genes, the reader is referred to recent reviews (Duboule, 2007;Gehring et al, 2009;Lemons and McGinnis, 2006;Maeda and Karch, 2009;Mallo et al, 2010;Merabet et al, 2005;Pearson et al, 2005;Pick and Heffer, 2012).…”

Pangênese, genes, epigênese

“…Estes são conser vados em diferentes classes de animais e exercem papel crucial na formação de diversas partes do corpo durante as primeiras fases do desenvolvimento (Graham, Papalopulu, Krumlauf, 1989;Duboule, Dollé, 1989). Dessa forma, restam poucas dúvidas sobre a importância desses genes na evolução da anatomia do grupo animal (Arthur, 2002;Pick, Heffer, 2012).…”

Evo-devo como disciplina integradora: la temporalidad de los procesos biológicos como estrategia de análisis

“…Este programa se centra en el estudio de los genes que controlan el desarrollo y de las redes de regulación génica asociadas a la evolución de la forma orgánica (Müller 2008). Específicamente, los procesos abordados son aquellos involucrados en los cambios genético-moleculares (en la secuencia de genes y la función de sus productos en las redes de regulación) vinculados con transformaciones macroevolutivas (principalmente las denominadas innovaciones evolutivas) (Cohn y Tickle 1999; Ronshaugen et al 2002;Lee et al 2003;Pick y Heffer 2012). Estos procesos son estudiados comparando la expresión y función de esos genes en el desarrollo de organismos de diversas especies.…”