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Short for evolution of development – a field of study concerned with the interplay of developmental genetics and evolution. It has developed in tandem with advances in molecular biology and genetics that have revealed how evolution of diversity in form and function can arise from mutations that alter the course or timing of development. Central is the concept that all complex animals share a ‘genetic toolkit’ inherited from a common ancestor dating back perhaps 600 million years. These genes, such as the Hox genes, and their signalling pathways are crucial in controlling development and are greatly conserved across a wide range of animal groups. Moreover, embryological development normally must proceed in an orderly sequence of stages (see ontogeny), disruption of which often leads to death of the embryo. Apart from these constraints on evolution, however, development can also contribute positively to evolution in numerous ways. One is the modular organization of body plans, such as repeated limbs or body segments, which is a universal feature of development. Duplication of such a module may lead to its further adaptation into a novel structure, such as pincers or mouthparts. Another area involves changes in the timing, location, or level of gene expression (see heterochrony) or alterations in the relative growth rates of different parts of the body. In this way relatively few mutations affecting development can have profound effects on the morphology of the mature organism.

Subjects: Biological Sciences.

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