Research on galapagos finches by peter and rosemary grant showed that a type of natural selection called

The type of natural selection is Directional Selection.

In directional selection, the phenotype which is more suitable to the existing environmental conditions is favored more over the other phenotypes. Thus, population of a particular phenotype increases gradually.

These birds changed from the ancestral bird in terms of the beak size, shape, etc.

thrombocytopenia, which is a deficiency in blood platelets, can cause bleeding and bruising in the dermis similar to senile purpura. other possible causes include: exposure to ultraviolet rays and aging skin are common causes of senile purpura. senile purpura may also be a sign of collagen loss in the skin and bones.