Many traits are effected by more than one gene. In this case there is often a so-called regulation gene, coordinating the other genes. A mutation in such a coordinating gene can have drastic consequences. In Mexico lives a family in which the males have a pelt all over their body, including their faces. Research has proven that in this family the regulation gene suppressing the pelt growth has been damaged. This is an example of the return of an ancestral characteristic, viz. the pelt. This phenomenon is called atavism. In this way some people possess a gill cleft in the neck. And very seldom a child with a small tail is born. Also a whale with hind legs is sometimes found. Know more? Atavism

This is a fine example of a mutation, self-found on the beach of the island of Terschelling (NL). The little shell left below is a monstrosity of the well-known wedge shell (on the right).  The aberrant specimen is much more convex and also smaller. If this characteric should be hereditary, then it is conceivable that from a small isolated population under special circumstances a new species would come into existence. When the aberrant animal can propagate, the trait stays in the gene pool , that is the whole of all genes of the species.

Evolution 13

Back

Stop

Next