Evolutionary developmental biology

Evolutionary developmental biology, informally known as evo-devo, is a field of <a href="/facts/Biological_research/1M1ee3pB">biological research</a> that compares the <a href="/facts/Developmental_biology/9dLJhCCv">developmental processes</a> of different <a href="/facts/Organism/j8JkL09u">organisms</a> to infer how developmental processes <a href="/facts/Evolution/Hj0qAaBk">evolved</a>.
The field grew from 19th-century beginnings, where <a href="/facts/Embryology/4mvpSkhC">embryology</a> faced a mystery: <a href="/facts/Zoology/6Kj13mBt">zoologists</a> did not know how <a href="/facts/Embryogenesis/1lFY4EoW">embryonic development</a> was controlled at the molecular level. <a href="/facts/Charles_Darwin/uwDLGItY">Charles Darwin</a> noted that having similar embryos implied common ancestry, but little progress was made until the 1970s. Then, <a href="/facts/Recombinant_DNA/dT3PL7M6">recombinant DNA</a> technology at last brought embryology together with <a href="/facts/Molecular_genetics/Q8wsm0FE">molecular genetics</a>. A key early discovery was that of <a href="/facts/Homeotic_gene/r7Ptbfbk">homeotic genes</a> that regulate development in a wide range of <a href="/facts/Eukaryote/SkwyPLMA">eukaryotes</a>.
The field is composed of multiple core evolutionary concepts. One is <a href="/facts/Deep_homology/QPxNmKFR">deep homology</a>, the finding that dissimilar organs such as the eyes of <a href="/facts/Insect/IgDNvnUL">insects</a>, <a href="/facts/Vertebrate/tT54FSTT">vertebrates</a> and <a href="/facts/Cephalopod/80GlMxHG">cephalopod</a> molluscs, long thought to have evolved separately, are controlled by similar genes such as <a href="/facts/Pax-6/31LAKRqo">pax-6</a>, from the <a href="/facts/Evo-devo_gene_toolkit/wRe0E6BN">evo-devo gene toolkit</a>. These genes are ancient, being <a href="/facts/Conserved_sequence/YAxy2Xa2">highly conserved</a> among <a href="/facts/Phylum/ELT3Jyax">phyla</a>; they generate the patterns in time and space which shape the embryo, and ultimately form the <a href="/facts/Body_plan/TykqU5bY">body plan</a> of the organism. Another is that species do not differ much in their structural genes, such as those coding for <a href="/facts/Enzyme/DSI1Fh7y">enzymes</a>; what does differ is the way that <a href="/facts/Regulation_of_gene_expression/9N4G341I">gene expression is regulated</a> by the <a href="/facts/Evo-devo_gene_toolkit/wRe0E6BN">toolkit genes</a>. These genes are reused, unchanged, many times in different parts of the embryo and at different stages of development, forming a complex cascade of control, switching other regulatory genes as well as structural genes on and off in a precise pattern. This multiple <a href="/facts/Pleiotropy/c14XQQ7g">pleiotropic</a> reuse explains why these genes are highly conserved, as any change would have many adverse consequences which <a href="/facts/Natural_selection/JXTte6en">natural selection</a> would oppose.
New <a href="/facts/Morphology_(biology)/Nl3B0myy">morphological</a> features and ultimately new species are produced by variations in the toolkit, either when genes are expressed in a new pattern, or when toolkit genes acquire additional functions. Another possibility is the <a href="/facts/Neo-Lamarckism/5bwVUmP8">neo-Lamarckian</a> theory that <a href="/facts/Epigenetics/UfAAERcn">epigenetic changes</a> are later <a href="/facts/Genetic_assimilation/Ac5AyYy5">consolidated at gene level</a>, something that may have been important early in the history of multicellular life.

Evolutionary developmental biology open-in-new

Evolutionary developmental biology