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Deep homology and the origins of evolutionary novelty


Do new anatomical structures arise de novo, or do they evolve from pre-existing structures? Advances in developmental genetics, palaeontology and evolutionary developmental biology have recently shed light on the origins of some of the structures that most intrigued Charles Darwin, including animal eyes, tetrapod limbs and giant beetle horns. In each case, structures arose by the modification of pre-existing genetic regulatory circuits established in early metazoans. The deep homology of generative processes and cell-type specification mechanisms in animal development has provided the foundation for the independent evolution of a great variety of structures.

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Figure 1: Deep homology of eye development and the parallel evolution of animal eyes.
Figure 2: Deep homology of late-phase Hox expression.
Figure 3: The evolution of beetle horns by co-option of a limb-outgrowth program.


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N.S. is supported by grants from the National Science Foundation and the National Geographic Society. C.T. is supported by grants from the National Institutes of Health. S.C. is an investigator of the Howard Hughes Medical Institute.

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Shubin, N., Tabin, C. & Carroll, S. Deep homology and the origins of evolutionary novelty. Nature 457, 818–823 (2009).

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