Evolutionary developmental biology (evolution of development
or informally, evo-devo) is a field of biology that compares the developmental
processes of different organisms to determine the ancestral relationship
between them, and to discover how developmental processes evolved.
It addresses
the origin and evolution of embryonic development; how modifications of
development and developmental processes lead to the production of novel
features, such as the evolution of feathers; the role of developmental
plasticity in evolution; how ecology impacts development and evolutionary
change; and the developmental basis of homoplasy and homology.
Although interest in the relationship between ontogeny and
phylogeny extends back to the nineteenth century, the contemporary field of
evo-devo has gained impetus from the discovery of genes regulating embryonic
development in model organisms.
General hypotheses remain hard to test because
organisms differ so much in shape and form. Nevertheless, it now appears that just as evolution tends to
create new genes from parts of old genes (molecular economy), evo-devo
demonstrates that evolution alters developmental processes to create new and
novel structures from the old gene networks (such as bone structures of the jaw
deviating to the ossicles of the middle ear) or will conserve (molecular
economy) a similar program in a host of organisms such as eye development genes
in molluscs, insects, and vertebrates.
Initially the major interest has been in
the evidence of homology in the cellular and molecular mechanisms that regulate
body plan and organ development. However subsequent approaches include
developmental changes associated with speciation.
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