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Diderot
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In her treatise 'Developmental plasticity and the origin of species differences' (PDF), Mary Jane West-Eberhard argues 'that the origin of species differences, and of novel phenotypes in general, involves the reorganization of ancestral phenotypes (developmental recombination) followed by the genetic accommodation of change'.
As an example West-Eberhard writes about 'the famous two-legged goat described in 1942 by the Dutch morphologist Slijper'. 'Slijper’s two-legged goat was born with a congenital defect of the front legs so that it could not walk on all fours, and so it learned to walk and run by using its hind legs alone.' After its accidental death Slijper documented 'remarkable changes in muscle and bone, including striking changes in the bones of the hind legs; the leg muscles, including a greatly thickened and elongated gluteal tongue and an innovative arrangement of small tendons, a modified shape of the thoracic skeleton, and extensive modifications of the pelvis.'
According to West-Eberhard 'a very large body of evidence shows that phenotypic novelty is largely reorganizational rather than a product of innovative genes.' And it is 'genetic change that follows, and is directed by, the reorganized condition of the phenotype.'
My questions are:
1. What is doing the reorganization?
2. How is genetic change directed by the reorganized condition of the phenotype?
As an example West-Eberhard writes about 'the famous two-legged goat described in 1942 by the Dutch morphologist Slijper'. 'Slijper’s two-legged goat was born with a congenital defect of the front legs so that it could not walk on all fours, and so it learned to walk and run by using its hind legs alone.' After its accidental death Slijper documented 'remarkable changes in muscle and bone, including striking changes in the bones of the hind legs; the leg muscles, including a greatly thickened and elongated gluteal tongue and an innovative arrangement of small tendons, a modified shape of the thoracic skeleton, and extensive modifications of the pelvis.'
According to West-Eberhard 'a very large body of evidence shows that phenotypic novelty is largely reorganizational rather than a product of innovative genes.' And it is 'genetic change that follows, and is directed by, the reorganized condition of the phenotype.'
My questions are:
1. What is doing the reorganization?
2. How is genetic change directed by the reorganized condition of the phenotype?
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